Rail road car truck and members thereof

Field of the Invention

This invention relates to the field of rail road cars, and, more particularly, to the field of three piece rail road car trucks for rail road cars.

Background of the Invention

Rail road cars in North America commonly employ double axle swivelling trucks known as "three piece trucks" to permit them to roll along a set of rails. The three piece terminology refers to a truck bolster and pair of first and second sideframes. In a three piece truck, the truck bolster extends cross-wise relative to the sideframes, with the ends of the truck bolster protruding through the sideframe windows. Forces are transmitted between the truck bolster and the sideframes by spring groups mounted in spring seats in the sideframes. The sideframes carry forces to the sideframe pedestals. The pedestals seat on bearing adapters, whence forces are carried in turn into the bearings, the axle, the wheels, and finally into the tracks. The <i>1980 Car &amp; Locomotive Cyclopedia</i> states at page 669 that the three piece truck offers "interchangeability, structural reliability and low first cost but does so at the price of mediocre ride quality and high cost in terms of car and track maintenance."

Ride quality can be judged on a number of different criteria. There is longitudinal ride quality, where, often, the limiting condition is the maximum expected longitudinal acceleration experienced during humping or flat switching, or slack run-in and run-out. There is vertical ride quality, for which vertical force transmission through the suspension is the key determinant. There is lateral ride quality, which relates to the lateral response of the suspension. There are also other phenomena to be considered, such as truck hunting, the ability of the truck to self steer, and, whatever the input perturbation may be, the ability of the truck to damp out undesirable motion. These phenomena tend to be inter-related, and the optimization of a suspension to deal with one phenomenon may yield a system that may not necessarily provide optimal performance in dealing with other phenomena.

In terms of optimizing truck performance, it may be advantageous to be able to obtain a relatively soft dynamic response to lateral and vertical perturbations, to obtain a measure of self steering, and yet to maintain resistance to lozenging (or parallelogramming). Lozenging, or parallelogramming, is non-square deformation of the truck bolster relative to the side frames of the truck as seen from above. Self steering may tend to be desirable since it may reduce drag and may tend to reduce wear to both the wheels and the track, and may give a smoother overall ride.

Among the types of truck discussed in this application are swing motion trucks. An earlier patent for a swing motion truck is <patcit id="pcit0001" dnum="US3670660A"><text>US Patent 3,670,660 of Weber et al., issued June 20, 1972</text></patcit>. This truck has unsprung lateral cross bracing, in the nature of a transom that links the sideframes together. By contrast, the description that follows describes several embodiments of truck that do not employ lateral unsprung cross-members, but that may use damper elements mounted in a four-cornered arrangement at each end of the truck bolster. An earlier patent for dampers is <patcit id="pcit0002" dnum="US3714905A"><text>US Patent 3,714,905 of Barber, issued February 6, 1973</text></patcit>.

Summary of the Invention

The present invention, in its various aspects, provides a rail road car truck with bi-directional rocking at the sideframe pedestal to wheelset axle end interface. It may also provide a truck that has self steering that is proportional to the weight carried by the truck. It may further have a longitudinal rocker at the sideframe to axle end interface. Further it may provide a swing motion truck with self steering. It may also provide a swing motion truck that has the combination of a swing motion lateral rocker and an elastomeric bearing adapter pad.

In an aspect of the invention, there is a wheelset-to-sideframe interface assembly for a railroad car truck. The interface assembly has a bearing adapter and a mating pedestal seat. The bearing adapter has first and second ends that form an interlocking insertion between a pair of pedestal jaws of a railroad car sideframe. The bearing adapter has a first rocking member. The pedestal seat has a second rocking member. The first and second rocking members are matingly engageable to permit lateral and longitudinal rocking between them. There is a resilient member mounted between the bearing adapter and pedestal seat. The resilient member has a portion formed that engages the first end of the bearing adapter. The resilient member has an accommodation formed to permit the mating engagement of the first and second rocking members.

In a feature of that aspect of the invention, the resilient member has the first and second ends formed for interposition between the bearing adapter and the pedestal aws of the sideframe. In another feature, the resilient member has the form of a Pennsy Pad with a relief formed to define the accommodation. In a further feature, the resilient member is an elastomeric member. In yet another feature, the elastomeric member is made of rubber material. In still another feature, the elastomeric member is made of a polyurethane material. In yet a further feature, the accommodation is formed through the elastomeric material and the first rocking member protrudes at least part way through the accommodation to meet the second rocking member. In an additional feature, the bearing adapter is a bearing adapter assembly which includes a bearing adapter body surmounted by the first rocker member. In another additional feature, the first rocker member is formed of a different material from the bearing body. In a further additional feature, the first rocker member is an insert.

In yet another additional feature, the first rocker member has a footprint with a profile conforming to the accommodation. In still another additional feature, the profile and the accommodation are mutually indexed to discourage mis-orientation of the first rocker member relative to the bearing adapter. In yet a further additional feature, the body and the first rocker member are keyed to discourage mis-orientation between them. In a further feature, the accommodation is formed through the resilient member and the second rocking member protrudes at least part way through said accommodation to meet the first rocking member. In another further feature, the pedestal seat includes an insert with the second rocking member formed in it. In yet another further feature, the second rocker member has a footprint with a profile conforming to the accommodation.

In still a further feature, the portion of the resilient member that is formed to engage the first end of the bearing adapter, when installed, includes elements that are interposed between the first end of the bearing adapter and the pedestal j aw to inhibit lateral and longitudinal movement of the bearing adapter relative to the jaw.

In another aspect of the invention the ends of the bearing adapter includes an end wall bracketed by a pair of corner abutments. The end wall and corner abutments define a channel to permit the sliding insertion of the bearing adapter between the pedestal jaw of the sideframe. The portion of the resilient member that is formed to engage the first end of the bearing adapter is the first end portion. The resilient member has a second end portion that is formed to engage the second end of the bearing adapter. The resilient member has a middle portion that extends between the first and second end portions. The accommodation is formed in the middle portion of the resilient member. In another feature, the resilient member has the form of a Pennsy Pad with a central opening formed to define the accommodation.

In another aspect of the invention, a wheelset-to-sideframe interface assembly for a rail road car truck has an interface assembly that has a bearing adapter, a pedestal seat and a resilient member. The bearing adapter has a first end and a second end that each have a end wall bracketted by a pair of corner abutments. The end wall and corner abutments co-operate to define a channel that permits insertion of the bearing adapter between a pair of thrust lugs of a sidewall pedestal. The bearing adapter has a first rocking member. The pedestal seat has a second rocking member to make engagement with the first rocking member. The first and second rocking members, when engaged, are operable to rock longitudinally relative to the sideframe to permit the rail road car truck to steer. The resilient member has a first end portion that is engageable with the first end of the bearing adapter for interposition between the first end of the bearing adapter and the first pedestal jaw thrust lug. The resilient member has a second end portion that is engageable with the second end of the bearing adapter for interposition between the second end of the bearing adapter and the second pedestal jaw thrust lug. The resilient member has a medial portion lying between the first and second end portions. The medial portion is formed to accommodate mating rocking engagement of the first and second rocking members.

In another feature, there is a resilient pad that is used with the bearing adapter which has a rocker member for mating and the rocking engagement with the rocker member of the pedestal seat. The resilient pad has a first portion for engaging the first end of the bearing adapter, a second portion for engaging a second end of the bearing adapter and a medial portion between the first and second end portions. The medial portion is formed to accommodate mating engagement of the rocker members.

In a feature of the aspect of the invention there is a wheelset-to-sideframe assembly kit that has a pedestal seat for mounting in the roof of a rail road car truck sideframe pedestal. There is a bearing adapter for mounting to a bearing of a wheelset of a rail road car truck and a resilient member for mounting to the bearing adapter. The bearing adapter has a first rocker element for engaging the seat in rocking relationship. The bearing adapter has a first end and a second end, both ends having an endwall and a pair of abutments bracketing the end wall to define a channel, that permits sliding insertion of the bearing adapter between a pair of sideframe pedestaljaw thrust lugs. The resilient member has a first portion that conforms to the first end of the bearing adapter for interpositioning between the bearing adapter and a thrust lug. The resilient member has a second portion connected to the first portion that, as installed, at least partially overlies the bearing adapter.

In another feature, the wheelset-to-sideframe assembly kit has a second portion of the resilient member with a margin that has a profile facing toward the first rocker element. The first rocker element is shaped to nest adjacent to the profile. In a further feature, wheelset-to-sideframe assembly kit has a bearing adapter that includes a body and the first rocker element is separable from that body. In still another feature, the wheelset-to-sideframe assembly kit has a second portion of the resilient member with a margin that has a profile facing toward the first rocker element which is shaped to nest adjacent the profile. In yet still another feature, the wheelset-to-sideframe assembly kit has a profile and first rocker element shaped to discourage mis-orientation of the first rocker element when installed. In another feature, the wheelset-to-sideframe assembly kit has a first rocker element with a body that is mutually keyed to facilitate the location of the first rocker element when installed. In still another feature, the wheelset-to-sideframe assembly kit has a first rocker element and body that are mutually keyed to discourage mis-orientation of the rocker element when installed. In yet still another feature, the wheelset-to-sideframe assembly kit has a first rocker element and a body with mutual engagement features. The features are mutually keyed to discourage mis-orientation of the rocker element when installed.

In a further feature, the kit has a second resilient member that conforms to the second end of the bearing adapter. In another feature, the wheelset-to-sideframe assembly kit includes a pedestal seat engagement fitting for locating the resilient feature relative to the pedestal seat on the assembly. In yet still another feature, the resilient member includes a second end portion that conforms to the second end of the bearing adapter.

In an additional feature, there is a bearing adapter for transmitting load between the wheelset bearing and a sideframe pedestal of a railroad car truck. It has at least a first and second land for engaging the bearing and a relief formed between the first and second land. The relief extends predominantly axially relative to the bearing. In another additional feature, the lands are arranged in an array that conforms to the bearing and the relief is formed at the apex of the array. In still another additional feature, the bearing adapter includes a second relief that extends circumferencially relative to the bearing. In yet still another additional feature, the axially extending relief and the circumferentially extending relief extends along a second axis of symmetry of the bearing adapter.

In a further feature, the radially extending relief extends along a first axis of symmetry of the bearing adapter and the circumferentially extending relief extends along a second axis of symmetry of the bearing adapter. In still a further feature, the bearing adapter has lands that are formed on a circumferencial arc. In yet still another feature, the bearing adapter has a rocker element that has an upwardly facing rocker surface. In yet still a further feature, the bearing adapter has a body with a rocker element that is separable from the body.

In another aspect of the invention, there is a bearing adapter for installation in a rail road car truck sideframe pedestal. The bearing adapter has an upper portion engageable with a pedestal seat, and a lower portion engageable with a bearing casing. The lower portion has an apex. The lower portion includes a first land for engaging a first portion of the bearing casing, and a second land region for engaging a second portion of the bearing casing. The first land lies to one side of the apex. The second land lies to the other side of the apex. At least one relief located between the first and second lands.

In an additional feature, the relief has a major dimension oriented to extend along the apex in a direction that runs axially relative to the bearing when installed. In another feature, the relief is located at the apex. In another feature there are at least two the reliefs, the two reliefs lying to either side of a bridging member, the bridging member running between the first and second lands.

In another aspect of the invention there is a kit for retro-fitting a railroad car truck having elastomeric members mounted over bearing adapters. The kit includes a mating bearing adapter and a pedestal seat pair. The bearing adapter and the pedestal seat have co-operable bi-directional rocker elements. The seat has a depth of section of greater than 1/2 inches.

In another aspect of the invention, there is a railroad car truck having a bolster and a pair of co-operating sideframes mounted on wheelsets for rolling operation along railroad tracks. Truck has rockers mounted between the sideframes to permit lateral swinging of the sideframes. The truck is free of lateral unsprung cross-bracing between the sideframes. The sideframes each have a lateral pendulum height, L, measured between a lower location at which gravity loads are passed into the sideframe, and an upper location at the rocker where a vertical reaction is passed into the sideframes. The rocker includes a male element having a radius of curvature, r₁, and a ratio of r₁: L is less than 3.

In a further feature of that aspect, the rocker has a female element in mating engagement with the male element. The female element has a radius of curvature R₁ that is greater than r₁, and the factor [ (1 /L)/((1 / r₁) - (1 / R₁))] is less than 3. In another further feature, R₁is at least 4/3 as large as r₁, and r₁ is greater than 15 inches.

In an aspect of the present invention, there is a rail road car truck that has a self steering capability and friction dampers in which the co-efficients of static and dynamic friction are substantially similar. It may include the added feature of lateral rocking at the sideframe pedestal to wheelset axle end interface. It may include self steering proportional to the weight carried by the truck. It may further have a longitudinal rocker at the sideframe to axle end interface. Further it may provide a swing motion truck with self steering. It may also provide a swing motion truck that has the combination of a swing motion lateral rocker and an elastomeric bearing adapter pad. In another feature, the truck may have dampers lying along the longitudinal centerline of the spring groups of the truck suspensions. In another feature, it may include dampers mounted in a four cornered arrangement. In another feature it may include dampers having modified friction surfaces on both the friction bearing face and on the obliquely angled face of the damper that seats in the bolster pocket.

In another aspect of the invention, a three piece rail road car truck has a truck bolster mounted transversely between a pair of sideframes. The truck bolster has ends, each of the ends being resiliently mounted to a respective one of the sideframes. The truck has a set of dampers mounted in a four cornered damper arrangement between each the bolster end and its respective sideframe. Each damper has a bearing surface mounted to work against a mating surface at a friction interface in a sliding relationship when the bolster moves relative to the sideframes. Each damper has a seat against which to mount a biasing device for urging the bearing face against the mating surface. The bearing surface of the damper has a dynamic co-efficient of friction and a static co-efficient of friction when working against the mating surface. The static and dynamic co-efficients of friction are of substantially similar magnitude.

In a further feature of that aspect of the invention, the co-efficients of friction have respective magnitudes within 10% of each other. In another feature, the co-efficients of friction are substantially equal. In another feature the co-efficients of friction lie in the range of 0.1 to 0.4. In still another feature, the co-efficients of friction lie in the range 0.2 to 0.35. In a further feature, the co-efficients of friction are about 0.30 (+/-10 %). In still another feature, the dampers each include a friction element mounted thereto, and the bearing surface is a surface of the friction element. In yet still another feature, the friction element is a composite surface element that includes a polymeric material.

In another feature of that aspect of the invention, the truck is a self-steering truck. In another feature, the truck includes a bearing adapter to sideframe pedestal interface that includes a self-steering apparatus. In another feature, the self-steering apparatus includes a rocker. In a further feature, the truck includes a bearing adapter to sideframe pedestal interface that includes a self-steering apparatus having a force-deflection characteristic varying as a function of vertical load. In still another feature, the truck has a bearing adapter to sideframe pedestal interface that includes a bi-directional rocker operable to permit lateral rocking of the sideframes and to permit self-steering of the truck.

In another feature of that aspect of the invention, each damper has an oblique face for seating in a damper pocket of a truck bolster of a rail road car truck, the bearing face is a substantially vertical face forbearing against a mating sideframe column wear surface, and, in use, the seat is oriented to face substantially downwardly. In another feature, the oblique face has a surface treatment for encouraging sliding of the oblique face relative to the damper pocket. In still another feature, the oblique face has a static coefficient of friction and a dynamic co-efficient of friction, and the co-efficients of static and dynamic friction of the oblique face are substantially equal. In a further feature, the oblique face and the bearing face both have sliding surface elements, and both of the sliding surface elements are made from materials having a polymeric component. In yet a further feature, the oblique face has a primary angle relative to the bearing surface, and a cross-wise secondary angle.

In another aspect of the invention, there is a three piece railroad car truck having a bolster transversely mounted between a pair of sideframes, and wheelsets mounted to the sideframes at wheelset to sideframe interface assemblies. The wheelset to sideframe interface assemblies are operable to permit self steering, and include apparatus operable to urge the wheelsets in a lengthwise direction relative to the sideframes to a minimum potential energy position relative to the sideframes. The self-steering apparatus has a force deflection characteristic that is a function of vertical load.

In a further aspect of the invention, there is a bearing adapter for a railroad car truck. The bearing adapter has a body for seating upon a bearing of a rail road truck wheelset, and a rocker member for mounting to the body. The rocker member has a rocking surface, the rocking surface facing away from the body when the rocker member is mounted to the body, and the rocker being made of a different material from the body.

In a further feature of that aspect, the rocker member is made from a tool steel. In another feature of that aspect of the invention, the rocker member is made from a metal of a grade used for the fabrication of ball bearings. In another feature, the body is made of cast iron. In another feature, the rocker member is a bi-directional rocker member. In still another feature, the rocking surface of the rocking member defines a portion of a spherical surface.

In another aspect of the invention, there is a three piece railroad car truck having rockers for self steering. In still another aspect, there is a railroad car truck having a sideframe, an axle bearing, and a rocker mounted between the sideframe and the axle bearing. The rocker has a transverse axis to permit rocking of and the bearing lengthwise relative to the sideframe.

In another aspect of the invention there is a three piece railroad car truck having a bolster mounted transversely to a pair of sideframes. The side frames have pedestal fittings and wheelsets mounted in the pedestal fittings. The pedestal fittings include rockers. Each rocker has a transverse axis to permit rocking in a lengthwise direction relative to the sideframes.

In another aspect of the invention there is a three piece railroad car truck having a truck bolster mounted transversely to a pair of side frames, each sideframes has fore and aft pedestal seat interface fittings, and a pair of wheelsets mounted to the pedestal seat interface fittings. The pedestal seat interface fittings include rockers operable to permit the truck to self steer.

In another aspect of the invention there is a railroad car truck having a sideframe, an axle bearing, and a bi-directional rocker mounted between the sideframe and the axle bearing. In still another aspect of the invention, there is a railroad car truck having a truck bolster mounted transversely between a pair of sideframes, and wheelsets mounted to the sideframes to permit rolling operation of the truck along a set of rail road tracks. The truck includes rocker elements mounted between the sideframes and the wheelsets. The rocker elements are operable to permit lateral swinging of the sideframes and to permit self-steering of the truck.

In another aspect of the invention there is a railroad car truck having a pair of sideframes, a pair of wheelsets having ends for mounting to the sideframes, and sideframe to wheelset interface fittings. The sideframe to wheelset interface fittings include rocking members having a first degree of freedom permitting lateral swinging of the sideframes relative to the wheelsets, and a second degree of freedom permitting longitudinal rocking of the wheelset ends relative to the sideframes.

In another aspect of the invention there is a railroad car truck having rockers formed on a compound curvature, the rockers being operable to permit both a lateral swinging motion in the truck and self steering of the truck. In still another aspect of the invention, there is a railroad car truck having a pair of sideframes, a pair of wheelsets having ends for mounting to the sideframes, and sideframe to wheelset interface fittings. The sideframe to wheelset interface fittings include rocking members having a first degree of freedom permitting lateral swinging of the sideframes relative to the wheelsets, a second degree of freedom permitting longitudinal rocking of the wheelset ends relative to the sideframes. The wheelset to sideframe interface fittings being torsionally compliant about a predominantly vertical axis.

In aspect of the invention there is a swing motion rail road car truck modified to include rocking elements mounted to permit self-steering. In yet another aspect there is a swing motion rail road car truckhaving a transverse bolster sprung between a pair of side frames, and a pair of wheelsets mounted to the sideframes at wheelset to sideframe interface fittings. The wheelset to sideframe interface fittings include swing motion rockers and elastomeric members mounted in series with the swing motion rockers to permit the truck to self-steer.

In another aspect of the invention, there is a rail road car truck having a truck bolster mounted transversely between a pair of sideframes, and wheelsets mounted to the sideframes at wheelset to sideframe interface fittings. The wheelset to sideframe interface fittings include rockers for permitting lateral swinging motion of the sideframes. The rockers have a male element and a mating female element. The male and female rocker elements are engaged for co-operative rocking operation. The female element has a radius of curvature in the lateral swinging direction of less than 25 inches. The wheelset to sideframe interface fittings are also operable to permit self steering.

In still another aspect of the invention there is a rail road car truck having a truck bolster mounted transversely between a pair of sideframes, and wheelsets mounted to the sideframes at wheelset to sideframe interface fittings. The wheelset to sideframe interface fittings include rockers for permitting lateral swinging motion of the sideframes. The rockers have a male element and a mating female element. The male and female rocker elements are engaged for co-operative rocking operation. The sideframes have an equivalent pendulum length, L_eq, when mounted on the rocker, of greater than 6 inches. The wheelset to sideframe interface fittings include an elastomeric member mounted in series with the rockers to permit self steering.

In yet another aspect of the invention there is a rail road car truck having a truck bolster mounted transversely between a pair of sideframes, and wheelsets mounted to the sideframes at wheelset to sideframe interface fittings. The wheelset to sideframe interface fittings include rockers for permitting self steering of the truck. The rockers have a male element and a mating female element. The male and female rocker elements are engaged for co-operative rocking operation, and the wheelset to sideframe interface fittings include an elastomeric member mounted in series with the rockers.

In still another aspect of the invention there is a rail road car truck having a transverse bolster sprung between two sideframes, and wheelsets mounted to the sideframes at wheelset to sideframe interface fittings, the truck having a spring groups and dampers seated in the bolster and biased by the spring groups to ride against the sideframes. The spring groups include a first damper biasing spring upon which a first damper of the dampers seats. The first damper biasing spring has a coil diameter. The first damper has a width of more than 150 % of the coil diameter.

In another aspect of the invention there is a rail road car truck having a bolster having ends sprung from a pair of sideframes, and wheelsets mounted to the sideframes at wheelset to sideframe interface fittings. The wheelset to sideframe interface fittings include bi-directional rocker fittings for permitting lateral swinging of the sideframes and for permitting self steering of the wheelsets. The truck has a four cornered arrangement of dampers mounted at each end of the bolster. In a further feature of that aspect of the invention the interface fittings are torsionally compliant about a predominantly vertical axis.

In another aspect there is a railroad car truck having a bolster transversly mounted between a pair of sideframes, and wheelsets mounted to the sideframes. The rail road car truck has a bi-directional longitudinal and lateral rocking interface between each sideframe and wheelset, and four cornered damper groups mounted between each sideframe and the truck bolster. In an additional feature of that aspect of the invention the rocking interface is torsionally compliant about a predominantly vertical axis. In another additional feature, the rocking interface is mounted in series with a torsionally compliant member.

In yet another aspect of the invention there is a self-steering rail road car truck having a transversely mounted bolster sprung between two sideframes, and wheelsets mounted to the sideframes. The sideframes are mounted to swing laterally relative to the wheelsets. The truck has friction dampers mounted between the bolster and the sideframes. The friction dampers have co-efficients of static friction and dynamic friction. The co-efficients of static and dynamic friction being substantially the same.

In still another aspect there is a self-steering rail road car truck having a transversely mounted bolster sprung between two sideframes, and wheelsets mounted to the sideframes. The sideframes are mounted to swing laterally relative to the wheelsets. The truck has friction dampers mounted between the bolster and the sideframes. The friction dampers have co-efficients of static friction and dynamic friction. The co-efficients of static and dynamic friction differ by less than 10 %. Expressed differently, the friction dampers having a co-efficient of static friction, U_s, and a co-efficient of dynamic friction, u_k, and a ratio of U_s/U_k lies in the range of 1.0 to 1.1. In another aspect of the invention, the truck has friction dampers mounted between the bolster and the sideframes in a sliding friction relationship that is substantially free of stick-slip behaviour. In another feature of that aspect of the invention the friction dampers include friction damper wedges having a first face for engaging one of the sideframes, and a second, sloped, face for engaging a bolster pocket. The sloped face is mounted in the bolster pocket in a sliding friction relationship that is substantially free of stick-slip behaviour.

In another aspect of the invention there is a self-steering rail road car truck having a bolster mounted between a pair of sideframes, and wheelsets mounted to the sideframes for rolling motion along railroad tracks. The wheelsets are mounted to the sideframes at wheelset to sideframe interface fittings. Those fittings are operable to permit lateral rocking of the sideframes. The truck has a set of friction dampers mounted between the bolster and each of the sideframes. The friction dampers have a first face in sliding friction relationship with the sideframes and a second face seated in a bolster pocket of the bolster. The first face, when operated in engagement with the sideframe, has a co-efficient of static friction and a co-efficient of dynamic friction, the co-efficients of static and dynamic friction of the first face differing by less than 10 %. The second face, when mounted within the bolster pocket, has a co-efficient of static friction, and a co-efficient of dynamic friction, and the co-efficients of static and dynamic friction of the second face differing by less than 10 %.

In yet another aspect of the invention there is a self-steering rail road car truck having a bolster mounted between a pair of sideframes, and wheelsets mounted to the sideframes for rolling motion along railroad tracks. The wheelsets are mounted to the sideframes at wheelset to sideframe interface fittings. The interface fittings are operable to permit lateral rocking of the sideframes. The truck has a set of friction dampers mounted between the bolster and each of the sideframes. The friction dampers have a first face in slidable friction relationship with the sideframes and a second face seated in a bolster pocket of the bolster. The first face and the side frame are co-operable and are in a substantially stick-slip free condition. The second face and the bolster pocket are also in a substantially stick-slip free condition.

In another aspect of the invention there is a rocker for a bearing adapter of a rail road car truck. The rocker has a rocking surface for rocking engagement with a mating surface of a pedestal seat of a sideframe of a railroad car truck. The rocking surface has a compound curvature to permit both lengthwise and sideways rocking. In a complementary aspect of the invention, there is a rocker for a pedestal seat of a sideframe of a rail road car truck. The rocker has a rocking surface for rocking engagement with a mating surface of a bearing adapter of a railroad car truck. The rocking surface has a compound curvature to permit both lengthwise and sideways rocking.

In an aspect of the invention there is a sideframe pedestal to axle bearing interface assembly for a three piece rail road car truck, the interface assembly having fittings operable to rock both laterally and longitudinally.

In an additional feature of that aspect of the invention the assembly includes mating surfaces of compound curvature, the compound curvature including curvature in both lateral and horizontal directions. In another feature, the assembly includes at least one rocker element and a mating element, the rocker and mating elements being in point contact with a mating element, the element in point contact being movable in rolling point contact with the mating element. In still another feature, the element in point contact is movable in rolling point contact with the mating element both laterally and longitudinally. In yet another feature, the fittings include rockingly matable saddle surfaces.

In another feature, the fittings include a male surface having a first compound curvature and a mating female surface having a second compound curvature in rocking engagement with each other, and one of the surfaces includes at least a spherical portion. In a further feature, the fittings include a non-rocking central portion in at least one direction. In still another feature, relative to a vertical axis of rotation, rocking motion of the fittings longitudinally is torsionally de-coupled from rocking of the fittings laterally. In a yet further feature the fittings include a force transfer interface that is torsionally compliant relative to torsional moments about a vertical axis. In still another feature, the assembly includes an elastomeric member.

In another aspect of the invention, there is a swing motion three piece rail road car truck having a laterally extending truck bolster, a pair of longitudinally extending sideframes to which the truck bolster is resiliently mounted, and wheelsets to which the side frames are mounted. Damper groups are mounted between the bolster and each of the sideframes. The damper groups each have a four-cornered damper layout, and wheelset to sideframe pedestal interface assemblies operable to permit lateral swinging motion of the sideframes and longitudinal self-steering of the wheelsets.

In a further aspect there is a rail road car truck having a truck bolster mounted between sideframes, and wheelsets to which the sideframes are mounted, and wheelset to sideframe interface assemblies by which to mount the sideframes to the wheelsets. The sideframe to wheelset interface assemblies include rocking apparatus to permit the sideframes to swing laterally. The rocking apparatus includes first and second surfaces in rocking engagement. At least a portion of the first surface has a first radius of curvature of less than 30 inches. The sideframe to wheelset interface includes self steering apparatus.

In a feature of that aspect of the invention, the self steering apparatus has a substantially linear force deflection characteristic. In another feature, the self steering apparatus has a force-deflection characteristic that varies with vertical loading of the sideframe to wheelset interface assembly. In a further feature, the force-deflection characteristic varies linearly with vertical loading of the sideframe to wheelset interface assembly. In another feature, the self steering apparatus includes a rocking element. In still another feature, the rocking element includes a rocking member subject to angular displacement about an axis transverse to one of the sideframes.

In another feature, the self steering apparatus includes male and female rocking elements, and at least a portion of the male rocking element has a radius of curvature of less than 45 inches. In still another feature, the self steering apparatus includes male and female rocking elements, and at least a portion of the female rocking element has a radius of curvature of less than 60 inches. In still another feature the self steering apparatus is self centering. In a further feature, the self steering apparatus is biased toward a central position.

In yet another feature, the self steering apparatus includes a resilient member. In a further feature of that further feature, the resilient member includes an elastomeric element. In another further feature, the resilient member is an elastomeric adapter pad assembly. In another feature, the resilient member is an elastomeric adapter assembly having a lateral force-displacement characteristic and a longitudinal force-displacement characteristic, and the longitudinal force-displacement characteristic is different from the lateral force-displacement characteristic. In another feature, the elastomeric adapter assembly is stiffer in lateral shear than in longitudinal shear. In again another feature, a rocker element is mounted above the elastomeric adapter pad assembly. In another feature, a rocker element is mounted directly upon the elastomeric adapter pad assembly. In a still further feature, the elastomeric adapter pad assembly includes and integral rocker member. In another feature, the three piece truck is a swing motion truck and the self steering apparatus includes an elastomeric bearing adapter pad.

In still another feature, the wheelsets have axles, and the axles have axes of rotation, and ends mounted beneath the sideframes, and, at one end of one of the axles, the self steering apparatus has a force deflection characteristic of at least one of the characteristics chosen from the set of force-deflection characteristic consisting of <ol id="ol0001" compact="compact"><li>(a) linear characteristic between 3000 lbs per inch and 10,000 pounds per inch of longitudinal deflection, measured at the axis of rotation at the end of the axle when the self steering apparatus bears one eighth of a vertical load of between 45,000 and 70,000 lbs.;</li><li>(b) linear characteristic between 16,000 lbs per inch and 60,000 pounds per inch of longitudinal deflection, measured at the axis of rotation at the end of the axle when the self steering apparatus bears one eighth of a vertical load of between 263,000 and 315,000 lbs.; and</li><li>(c) a linear characteristic between 0.3 and 2.0 lbs per inch of longitudinal deflection, measured at the axis of rotation at the end of the axle per pound of vertical load passed into the one end of the one axle.</li></ol>

In another aspect of the invention there is a three piece rail road freight car truck having self steering apparatus, wherein the passive steering apparatus includes at least one longitudinal rocker.

In an aspect of the invention, there is a three piece rail road freight car truck having passive self steering apparatus, the self steering apparatus having a linear force-deflection characteristic, and the force-deflection characteristic varying as a function of vertical loading of the truck.

In an additional feature of that aspect of the invention, the force-displacement characteristic varies linearly with vertical loading of the truck. In another feature, the self steering apparatus includes a rocker mechanism. In another feature, the rocker mechanism is displaceable from a minimum energy state under drag force applied to a wheel of one of the wheelsets. In still another feature, the force-deflection characteristic lies in the range of between about 0.4 lbs and 2.0 lbs per inch of deflection, measured at a center of and end of an axle of a wheelset of the truck per pound of vertical load passed into the end of the axle of the wheelset. In a further feature, the force deflection characteristic lies in the range of 0.5 to 1.8 Ibs per inch per pound of vertical load passed into the end of the axle of the wheelset.

In yet another aspect of the invention there is a three piece rail road freight car truck having a transversely extending truck bolster, a pair of side frames mounted at opposite ends of the truck bolster, and resiliently connected thereto, and wheelsets. The sideframes are mounted to the wheelsets at sideframe to wheelset interface assemblies. At least one of the sideframe to wheelset interface assemblies is mounted between a first end of an axle of one of the wheelsets, and a first pedestal of a first of the sideframes. The wheelset to sideframe interface assembly includes a first line contact rocker apparatus operable to permit lateral swinging of the first sideframe and a second line contact rocker apparatus operable to permit longitudinal displacement of the first end of the axle relative to the first sideframe.

In a feature of that aspect of the invention, the first and second rocker apparatus are mounted in series with a torsionally compliant member, the torsionally complaint member being compliant to torsional moments applied about a vertical axis. In another feature, a torsionally compliant member is mounted between the first and second rocker apparatus, the torsionally compliant member being torsionally compliant about a vertical axis.

In a further aspect of the invention, there is a bearing adapter for a three piece rail road freight car truck, the bearing adapter having a rocking contact surface for rocking engagement with a mating surface of a sideframe pedestal fitting, the rocking contact surface of the bearing adapter having a compound curvature.

In another feature of that aspect of the invention, the compound curvature is formed on a first male radius of curvature and a second male radius of curvature oriented cross-wise thereto. In another feature, the compound curvature is saddle shaped. In a further feature, the compound curvature is ellipsoidal. In a further feature, the curvature is spherical.

In a still further aspect there is a railroad car truck having a laterally extending truck bolster. The truck bolster has first and second ends. First and second longitudinally extending sideframes are resiliently mounted at the first and second ends of the bolster respectively. The side frames are mounted on wheelsets at sideframe to wheelset mounting interface assemblies. A four cornered damper group is mounted between each end of the truck bolster and the respective side frame to which that end is mounted. The sideframe to wheelset mounting interface assemblies are torsionally compliant about a vertical axis.

In a feature of that aspect of the invention, the truck is free of unsprung lateral cross-members between the sideframes. In another feature, the sideframes are mounted to swing laterally. In still another feature, the sideframe to wheelset mounting interface assemblies include self steering apparatus.

In another aspect of the invention, there is a railroad freight car truck having wheelsets mounted in a pair of sideframes, the sideframes having sideframe pedestals for receiving the wheelsets. The sideframe pedestals have sideframe pedestal jaws. The sideframe pedestal jaws include sideframe pedestal jaw thrust blocks. The wheelsets have bearing adapters mounted thereto for installation between the jaws. The sideframe pedestals have respective pedestal seat members rockingly co-operable with the bearing adapter. The truck has members mounted intermediate the jaws and the bearing adapters for urging the bearing adapter to a centered position relative to the pedestal seat. In another aspect, there is a member for placement between the thrust lug of a railroad car sideframe pedestal jaw and the end wall and corner abutments of a bearing adapter, the member being operable to urge the bearing adapter to an at rest position relative to the sideframe.

In another aspect of the invention there is a sideframe pedestal to axle bearing interface assembly for a three piece rail road car truck. The interface assembly has fittings operable to rock both laterally and longitudinally, and the interface assembly includes a bearing assembly having one of the rocking surface fittings defined integrally thereon.

In an additional feature of that aspect of the invention the bearing assembly includes a rocking surface of compound curvature. In another feature, the fittings include rockingly matable saddle surfaces. In yet another feature, the fittings include a male surface having a first compound curvature and a mating female surface having a second compound curvature in rocking engagement with each other. One of the surfaces includes at least a spherical portion. In still another feature, relative to a vertical axis of rotation, rocking motion of the fittings longitudinally is torsionally de-coupled from rocking of the fittings laterally. In still yet another feature, the fittings include a force transfer interface that is torsionally compliant relative to torsional moments about a vertical axis. In a further feature, the assembly includes a resilient biasing member.

In an aspect of the invention there is a sideframe pedestal to axle bearing interface assembly for a three piece rail road car truck. The interface assembly has fittings operable to rock both laterally and longitudinally, and the interface assembly includes a bearing assembly having one of the rocking surface fittings defined integrally thereon.

In an additional feature of that aspect of the invention, the bearing assembly includes a rocking surface of compound curvature. In another feature, the fittings include rockingly matable saddle surfaces. In still another feature, the fittings include a male surface having a first compound curvature and a mating female surface having a second compound curvature in rocking engagement with each other, and one of the surfaces includes at least a spherical portion. In yet another feature, relative to a vertical axis of rotation, rocking motion of the fittings longitudinally is torsionally de-coupled from rocking of the fittings laterally. In still yet another feature, the fittings include a force transfer interface that is torsionally compliant relative to torsional moments about a vertical axis. In a further feature, the assembly includes a resilient biasing member.

In another aspect of the invention, there is a sideframe pedestal to axle bearing interface assembly for a three piece rail road car truck. The interface assembly has mating rocking surfaces. The assembly includes a bearing mounted to an end of a wheelset axle. The bearing has an outer ring, and one of the rocking surfaces is rigidly fixed relative to the bearing.

In still another aspect of the invention, there is a bearing for mounting to one end of an axle of a wheelset of a three-piece railroad car truck. The bearing has an outer member mounted in a position to permit the end of the axle to rotate relative thereto, and the outer member has a rocking surface formed thereon for engaging a mating rolling contact surface of a pedestal seat member of a sideframe of the three piece truck. In an additional feature of that aspect of the invention, the bearing has an axis of rotation coincident with a centerline axis of the axle and the surface has a region of minimum radial distance from the center of rotation and a positive derivative dr/dθ between the region and points angularly adjacent thereto on either side.

In another feature, the surface is cylindrical. In yet another feature, the surface has a constant radius of curvature. In still another feature, the cylinder has an axis parallel to the axis of rotation of the bearing. In still yet another feature, when installed in the three piece truck, the surface has a local minimum potential energy position, the position of minimum potential energy being located between positions of greater potential energy. In yet another feature, the surface is a surface of compound curvature. In still yet another feature, the surface has the form of a saddle. In a further feature, the surface has a radius of curvature. The bearing has an axis of rotation, and a region of minimum radial distance from the axis of rotation. The radius of curvature is greater than the minimum radial distance.

In yet a further feature, there is a combination of a bearing and a pedestal seat. In an additional feature, the bearing has an axis of rotation. A first location on the surface of the bearing lies radially closer to the axis of rotation than any other location thereon; a first distance, L is defined between the axis of rotation and the first location. The surface of the bearing and the surface of the pedestal seat each have a radius of curvature and mate in a male and female relationship. One radius of curvature is a male radius of curvature <b>r₁</b>. The other radius of curvature is a female radius of curvature, <b>R₂</b>; <b>r₁</b> being greater than <b>L</b>, <b>R₂</b> is greater than <b>r₁</b>, and <b>L</b>, <b>r₁</b> and <b>R₂</b> conform to the formula <b>L^-1</b> - (<b>r₁^-1</b> - <b>R₂^-1</b>) &gt; 0. In another additional feature, the rocking surfaces are co-operable to permit self steering.

These and other aspects and features of the invention may be understood with reference to the detailed descriptions of the invention and the accompanying illustrations as set forth below.

Brief Description of the Figures

The principles of the invention may better be understood with reference to the accompanying figures provided by way of illustration of an exemplary embodiment, or embodiments, incorporating principles and aspects of the present invention, and in which: <ul id="ul0001" list-style="none" compact="compact"><li><figref idref="f0001">Figure <b>1a</b></figref> shows an isometric view of an example of an embodiment of a railroad car truck according to an aspect of the present invention;</li><li><figref idref="f0001">Figure <b>1b</b></figref>shows a top view of the railroad car truck of <figref idref="f0001">Figure <b>1a</b></figref><b>;</b></li><li><figref idref="f0001">Figure <b>1c</b></figref>shows a side view of the railroad car truck of <figref idref="f0001">Figure <b>1a</b></figref><b>;</b></li><li><figref idref="f0002">Figure <b>1d</b></figref> shows an exploded view of a portion of a truck similar to that of <figref idref="f0001">Figure <b>1a</b></figref><b>;</b></li><li><figref idref="f0002">Figure <b>1e</b></figref> is an exploded, sectioned view of an example of an alternate three piece truck to that of <figref idref="f0001">Figure <b>1a</b></figref><b>,</b> having dampers mounted along the spring group centerlines;</li><li><figref idref="f0003">Figure <b>1f</b></figref> shows an isometric view of an example of an embodiment of a railroad car truck according to an aspect of the present invention;</li><li><figref idref="f0003">Figure <b>1g</b></figref> shows a side view of the railroad car truck of <figref idref="f0003">Figure <b>1f</b></figref><b>;</b></li><li><figref idref="f0003">Figure <b>1h</b></figref>shows a top view of the railroad car truck of <figref idref="f0003">Figure <b>1f</b></figref><b>;</b></li><li>Figure li is a split view showing, in one half an end view of the truck of Figure If, and in the other half and a section taken level with the truck center;</li><li><figref idref="f0003">Figure <b>1j</b></figref>shows a spring layout for the truck of <figref idref="f0003"><b>Figure 1f</b></figref><b>;</b></li><li><figref idref="f0004">Figure <b>2a</b></figref> is an enlarged detail of a side view of a truck such as the truck of <figref idref="f0001">Figure <b>1a, 1b, 1c</b></figref> or <figref idref="f0002"><b>1e</b></figref> taken at the sideframe pedestal to bearing adapter interface;</li><li><figref idref="f0004">Figure <b>2b</b></figref> shows a lateral cross-section through the sideframe pedestal to bearing adapter interface of <figref idref="f0004">Figure <b>2a</b></figref><b>,</b> taken at the wheelset axle centerline;</li><li><figref idref="f0004">Figure <b>2c</b></figref> shows the cross-section of <figref idref="f0004">Figure <b>2b</b></figref> in a laterally deflected condition;</li><li><figref idref="f0005">Figure <b>2d</b></figref> is a longitudinal section of the pedestal seat to bearing adapter interface of <figref idref="f0004">Figure <b>2a</b></figref><b>,</b> on the longitudinal plane of symmetry of the bearing adapter;</li><li><figref idref="f0005">Figure <b>2e</b></figref> shows the longitudinal section of <figref idref="f0005">Figure <b>2d</b></figref> as longitudinally deflected;</li><li><figref idref="f0005">Figure <b>2f</b></figref> shows a top view of the detail of <figref idref="f0004">Figure <b>2a</b></figref><b>;</b></li><li><figref idref="f0005">Figure <b>2g</b></figref> shows a staggered section of the bearing adapter of <figref idref="f0004">Figure <b>2a</b></figref><b>,</b> on section lines <b>'2g - 2g'</b> of <figref idref="f0004">Figure <b>2a</b></figref><b>;</b></li><li><figref idref="f0006">Figure <b>3a</b></figref> shows an exploded isometric view of an alternate sideframe pedestal to bearing adapter interface to that of <figref idref="f0004">Figure <b>2a</b></figref><b>;</b></li><li><figref idref="f0006">Figure <b>3b</b></figref> shows an alternate bearing adapter to pedestal seat interface to that of <figref idref="f0006">Figure <b>3a</b></figref><b>;</b></li><li><figref idref="f0007">Figure <b>3c</b></figref> shows a sectional view of the assembly of <figref idref="f0006">Figure <b>3b</b></figref><b>;</b> taken on a longitudinal-vertical plane of symmetry thereof;</li><li><figref idref="f0007">Figure <b>3d</b></figref> shows a stepped sectional view of a detail of the assembly of <figref idref="f0006">Figure <b>3b</b></figref> taken <b>on 3d - 3d' of</b><figref idref="f0007">Figure <b>3c</b></figref><b>;</b></li><li><figref idref="f0007">Figure <b>3e</b></figref> shows an exploded view of another alternative embodiment of bearing adapter to pedestal seat interface to that of <figref idref="f0006">Figure <b>3a</b></figref><b>;</b></li><li><figref idref="f0008">Figure <b>4a</b></figref> shows an isometric view of a retainer pad of the assembly of <figref idref="f0006">Figure <b>3a</b></figref><b>,</b> taken from above, and in front of one corner;</li><li><figref idref="f0008">Figure <b>4b</b></figref> is an isometric view from above and behind the retainer pad of <figref idref="f0008">Figure <b>4a</b></figref>;</li><li><figref idref="f0008">Figure <b>4c</b></figref> is a bottom view of the retainer pad of <figref idref="f0008">Figure <b>4a</b></figref>;</li><li><figref idref="f0008">Figure <b>4d</b></figref> is a front view of the retainer pad of <figref idref="f0008">Figure <b>4a</b></figref>;</li><li><figref idref="f0008">Figure <b>4e</b></figref> is a section on '<b>4e - 4e</b>' of <figref idref="f0008">Figure 4d</figref> of the retainer pad of <figref idref="f0008">Figure <b>4a</b></figref>;</li><li><figref idref="f0008">Figure <b>5</b></figref> shows an alternate bolster, similar to that of <figref idref="f0002">Figure <b>1d</b></figref>, with a pair of spaced apart bolster pockets, and inserts with primary and secondary wedge angles;</li><li><figref idref="f0009">Figure <b>6a</b></figref> is a cross-section of an alternate damper such as may be used, for example, in the bolster of the trucks of <figref idref="f0001">Figures <b>1a, 1b, 1c,</b></figref><figref idref="f0002"><b>1d</b></figref> and <figref idref="f0003"><b>1f</b></figref><b>;</b></li><li><figref idref="f0009">Figure <b>6b</b></figref> shows the damper of <figref idref="f0009">Figure <b>6a</b></figref> with friction modifying pads removed;</li><li><figref idref="f0009">Figure <b>6c</b></figref> is a reverse view of a friction modifying pad of the damper of <figref idref="f0009">Figure <b>6a</b></figref><b>;</b></li><li><figref idref="f0010">Figure <b>7a</b></figref> is a front view of a friction damper for a truck such as that of <figref idref="f0001">Figure <b>1a</b></figref><b>;</b></li><li><figref idref="f0010">Figure <b>7b</b></figref> shows a side view of the damper of <figref idref="f0010">Figure <b>7a</b></figref><b>;</b></li><li><figref idref="f0010">Figure <b>7c</b></figref> shows a rear view of the damper of <figref idref="f0010">Figure <b>7b</b></figref><b>;</b></li><li><figref idref="f0010">Figure <b>7d</b></figref> shows a top view of the damper of <figref idref="f0010">Figure <b>7a</b></figref><b>;</b></li><li><figref idref="f0010">Figure <b>7e</b></figref> shows a cross-sectional view on the centerline of the damper of <figref idref="f0010">Figure <b>7a</b></figref> taken on section <b>'7e - 7e'</b> of <figref idref="f0010">Figure <b>7c</b></figref><b>;</b></li><li><figref idref="f0010">Figure <b>7f</b></figref> is a cross-section of the damper of <figref idref="f0010">Figure <b>7a</b></figref> taken on section <b>'7f - 7'</b> of <figref idref="f0010">Figure <b>7e</b></figref><b>;</b></li><li><figref idref="f0009">Figure <b>7g</b></figref> shows an isometric view of an alternate damper to that of <figref idref="f0010">Figure <b>7a</b></figref> having a friction modifying side face pad;</li><li><figref idref="f0009">Figure <b>7h</b></figref> shows an isometric view of a further alternate damper to that of <figref idref="f0010">Figure <b>7a</b></figref>, having a "wrap-around" friction modifying pad;</li><li><figref idref="f0011">Figure <b>8a</b></figref> shows an exploded isometric installation view of an alternate bearing adapter assembly to that of <figref idref="f0006">Figure <b>3a</b></figref><b>;</b></li><li><figref idref="f0011">Figure <b>8b</b></figref> shows an isometric, assembled view of the bearing adapter assembly of <figref idref="f0011">Figure <b>8a</b></figref>;</li><li><figref idref="f0011">Figure <b>8c</b></figref> shows the assembly of <figref idref="f0011">Figure <b>8b</b></figref> with a rocker member thereof removed;</li><li><figref idref="f0012">Figure <b>8d</b></figref> shows the assembly of <figref idref="f0011">Figure <b>8b</b></figref>, as installed, in longitudinal cross-section;</li><li><figref idref="f0012">Figure <b>8e</b></figref> is an installed view of the assembly of <figref idref="f0011">Figure <b>8b</b></figref>, on section '<b>8e - 8e</b>' of <figref idref="f0012">Figure <b>8d</b></figref>;</li><li><figref idref="f0012">Figure <b>8f</b></figref> shows the assembly of <figref idref="f0011">Figure <b>8b</b></figref>, as installed, in lateral cross section;</li><li><figref idref="f0013">Figure <b>9a</b></figref> shows an exploded isometric view of an alternate assembly to that of <figref idref="f0006">Figure <b>3a</b></figref><b>;</b></li><li><figref idref="f0013">Figure <b>9b</b></figref> shows an exploded isometric view similar to the view of <figref idref="f0013">Figure <b>9a</b></figref><b>,</b> showing a bearing adapter assembly incorporating an elastomeric pad;</li><li><figref idref="f0014">Figure <b>10a</b></figref> shows an exploded isometric view of an alternate assembly to that of <figref idref="f0006">Figure <b>3a</b></figref>;</li><li><figref idref="f0014">Figure <b>10b</b></figref> shows a perspective view of a bearing adapter of the assembly of <figref idref="f0014">Figure <b>10a</b></figref> from above and to one corner;</li><li><figref idref="f0014">Figure <b>10c</b></figref> shows a perspective of the bearing adapter of <figref idref="f0014">Figure <b>10b</b></figref> from below;</li><li><figref idref="f0014">Figure <b>10d</b></figref> shows a bottom view of the bearing adapter of <figref idref="f0014">Figure <b>10b</b></figref><b>;</b></li><li><figref idref="f0014">Figure <b>10e</b></figref> shows a longitudinal section of the bearing adapter of <figref idref="f0014">Figure <b>10b</b></figref> taken on section <b>10e - 10e'</b> of <figref idref="f0014">Figure <b>10d</b></figref><b>;</b> and</li><li><figref idref="f0014">Figure <b>10f</b></figref> shows a transverse section of the bearing adapter of <figref idref="f0014">Figure <b>10b</b></figref> taken on section <b>'10f - 10f'</b> of <figref idref="f0014">Figure <b>10d</b></figref><b>;</b></li><li><figref idref="f0015">Figure <b>11a</b></figref> is an exploded view of an alternate bearing adapter assembly to that of <figref idref="f0006">Figure <b>3a</b></figref><b>;</b></li><li><figref idref="f0015">Figure <b>11b</b></figref> shows a view of the bearing adapter of <figref idref="f0015">Figure <b>11a</b></figref> from below and to one corner;</li><li><figref idref="f0015">Figure <b>11c</b></figref> is a top view of the bearing adapter of <figref idref="f0015">Figure <b>11b</b></figref><b>;</b></li><li><figref idref="f0015">Figure <b>11d</b></figref> is a lengthwise section of the bearing adapter of <figref idref="f0015">Figure <b>11c</b></figref> on <b>'11d - 11d';</b></li><li><figref idref="f0015">Figure <b>11e</b></figref> is a cross-wise section of the bearing adapter of <figref idref="f0015">Figure <b>11c</b></figref> on <b>'11e - 11e';</b> and</li><li><figref idref="f0015">Figure <b>11f</b></figref> is a set of views of a resilient pad member of the assembly of <figref idref="f0015">Figure <b>11a</b></figref><b>;</b></li><li><figref idref="f0015">Figure <b>11g</b></figref> shows a view of the bearing adapter of <figref idref="f0015">Figure <b>11a</b></figref> from above and to one corner;</li><li><figref idref="f0016">Figure <b>12a</b></figref> shows an exploded isometric view of an alternate bearing adapter to pedestal seat assembly to that of <figref idref="f0006">Figure <b>3a</b></figref><b>;</b></li><li><figref idref="f0016">Figure <b>12b</b></figref> shows a longitudinal central section of the assembly of <figref idref="f0016">Figure <b>12a</b></figref><b>,</b> as assembled;</li><li><figref idref="f0016">Figure <b>12c</b></figref> shows a section on <b>'12c-12c'</b> of <figref idref="f0016">Figure <b>12b</b></figref><b>;</b> and</li><li><figref idref="f0016">Figure <b>12d</b></figref> shows a section on <b>'12d-12d'</b> of <figref idref="f0016">Figure <b>12b</b></figref><b>;</b></li><li><figref idref="f0017">Figure <b>13a</b></figref> shows a top view of an embodiment of bearing adapter and pedestal seat such as could be used in a side frame pedestal similar to that of <figref idref="f0004">Figure <b>2a</b></figref><b>,</b> with the seat inverted to reveal a female depression formed therein for engagement with the bearing adapter;</li><li><figref idref="f0017">Figure <b>13b</b></figref> shows a side view of the bearing adapter and seat of <figref idref="f0017">Figure <b>13a</b></figref><b>;</b></li><li><figref idref="f0017">Figure <b>13c</b></figref> shows a longitudinal section of the bearing adapter of <figref idref="f0017">Figure <b>13a</b></figref> taken on section <b>`13c -13c'</b> of <figref idref="f0017">Figure <b>13d</b></figref><b>;</b></li><li><figref idref="f0017">Figure <b>13d</b></figref> shows an end view of the bearing adapter and pedestal seat of <figref idref="f0017">Figure <b>13a</b></figref><b>;</b></li><li><figref idref="f0017">Figure <b>13e</b></figref> shows a transverse section of the bearing adapter of <figref idref="f0017">Figure <b>13a</b></figref>, taken on the wheelset axle centreline;</li><li><figref idref="f0018">Figure <b>13f</b></figref> is a section in the transverse plane of symmetry of a bearing adapter and pedestal seat pair like that of <figref idref="f0017">Figure <b>13e</b></figref>, with inverted rocker and seat portions;</li><li><figref idref="f0018">Figure <b>13g</b></figref> shows a cross-section on the longitudinal plane of symmetry of the bearing adapter and pedestal seat pair of <figref idref="f0018">Figure <b>13f</b></figref>;</li><li><figref idref="f0019">Figure <b>14a</b></figref> shows an isometric view of an alternate embodiment of bearing adapter and pedestal seat to that of <figref idref="f0017">Figure <b>13a</b></figref> having a fully curved upper surface;</li><li><figref idref="f0019">Figure <b>14b</b></figref> shows a side view of the bearing adapter and seat of <figref idref="f0019">Figure <b>14a</b></figref><b>;</b></li><li><figref idref="f0019">Figure <b>14e</b></figref> shows an end view of the bearing adapter and seat of <figref idref="f0019">Figure <b>14a</b></figref><b>;</b></li><li><figref idref="f0019">Figure <b>14d</b></figref> shows a cross-section of the bearing adapter and pedestal seat of <figref idref="f0019">Figure <b>14a</b></figref> taken on the longitudinal plane of symmetry;</li><li><figref idref="f0019">Figure <b>14e</b></figref> shows a cross-section of the bearing adapter and pedestal seat of <figref idref="f0019">Figure <b>14a</b></figref> taken on the transverse plane of symmetry;</li><li><figref idref="f0018">Figure <b>15a</b></figref> shows a top view of an alternate bearing adapter and an inverted view of an alternate female pedestal seat to that of <figref idref="f0017">Figure <b>13a</b></figref><b>;</b></li><li><figref idref="f0018">Figure <b>15b</b></figref> shows a longitudinal section of the bearing adapter of <figref idref="f0018">Figure <b>15a</b></figref><b>;</b></li><li><figref idref="f0018">Figure <b>15c</b></figref> shows an end view of the bearing adapter and seat of <figref idref="f0018">Figure <b>15a</b></figref><b>;</b></li><li><figref idref="f0020">Figure <b>16a</b></figref> shows an isometric view of a further embodiment of bearing adapter and seat combination to that of <figref idref="f0017">Figure <b>13a</b></figref><b>,</b> in which the bearing adapter and pedestal seat have saddle shaped engagement interfaces;</li><li><figref idref="f0020">Figure <b>16b</b></figref> shows an end view of the bearing adapter and pedestal seat of <figref idref="f0020">Figure <b>16a</b></figref><b>;</b></li><li><figref idref="f0020">Figure <b>16c</b></figref> shows a side view of the bearing adapter and pedestal seat of <figref idref="f0020">Figure <b>16a</b></figref><b>;</b></li><li><figref idref="f0020">Figure <b>16d</b></figref> is a lateral section of the adapter and pedestal seat of <figref idref="f0020">Figure <b>16a</b></figref><b>;</b></li><li><figref idref="f0020">Figure <b>16e</b></figref> is a longitudinal section of the adapter and pedestal seat of <figref idref="f0020">Figure <b>16a</b></figref><b>;</b></li><li><figref idref="f0021">Figure <b>16f</b></figref> shows a transverse cross section of a bearing adapter and pedestal seat pair having an inverted interface to that of <figref idref="f0020">Figure 16a</figref>;</li><li><figref idref="f0021">Figure <b>16g</b></figref> shows a longitudinal cross section for the bearing adapter and pedestal seat pair of <figref idref="f0021">Figure <b>16f</b></figref>;</li><li><figref idref="f0022">Figure <b>17a</b></figref> shows an exploded side view of a further alternate bearing adapter and seat combination to that of <figref idref="f0017">Figure <b>13a</b></figref><b>,</b> having a pair of cylindrical rocker elements, and a pivoted connection therebetween;</li><li><figref idref="f0022">Figure <b>17b</b></figref> shows an exploded end view of the bearing adapter and seat of <figref idref="f0022">Figure <b>17a</b></figref><b>;</b></li><li><figref idref="f0022">Figure <b>17c</b></figref> shows a cross-section of the bearing adapter and seat of <figref idref="f0022">Figure <b>17a</b></figref><b>,</b> as assembled, taken on the longitudinal centreline thereof;</li><li><figref idref="f0022">Figure <b>17d</b></figref> shows a cross-section of the bearing adapter and seat of <figref idref="f0022">Figure <b>17a</b></figref><b>,</b> as assembled, taken on the transverse centreline thereof;</li><li><figref idref="f0023">Figure <b>17e</b></figref> shows possible permutations of the assembly of <figref idref="f0022">Figure <b>17a</b></figref><b>;</b></li><li><figref idref="f0021">Figure <b>18a</b></figref> is an exploded end view of an alternate version of bearing adapter and seat assembly to that of <figref idref="f0022">Figure <b>17a</b></figref> having an elastomeric intermediate member;</li><li><figref idref="f0021">Figure <b>18b</b></figref> shows an exploded side view of the assembly of <figref idref="f0021">Figure <b>18a</b></figref><b>;</b></li><li><figref idref="f0024">Figure <b>19a</b></figref> is a side view of alternate assembly to that of <figref idref="f0017">Figure <b>13a</b></figref> or <figref idref="f0020"><b>16a</b></figref><b>,</b> employing an elastomeric shear pad and a laterally swinging rocker;</li><li><figref idref="f0024">Figure <b>19b</b></figref> shows a transverse cross-section of the assembly of <figref idref="f0024">Figure <b>19a</b></figref><b>,</b> taken on the axle center line thereof;</li><li><figref idref="f0025">Figure <b>19c</b></figref> shows a cross section of the assembly of <figref idref="f0024">Figure <b>19a</b></figref> taken on the longitudinal plane of symmetry of the bearing adapter;</li><li><figref idref="f0025">Figure <b>19d</b></figref> shows a sectional view of the alternate assembly of <figref idref="f0024">Figure <b>19a</b></figref>, as viewed from above, taken on the staggered section indicated as <b>'19d - 19d';</b></li><li><figref idref="f0026">Figure <b>19e</b></figref> shows an end view of an alternate rocker combination to that of <figref idref="f0024">Figure <b>19a</b></figref> employing an elastomeric pad;</li><li><figref idref="f0026">Figure <b>19f</b></figref> shows a perspective view of the alternate pad combination of <figref idref="f0026">Figure <b>19e</b></figref>;</li><li><figref idref="f0026">Figure <b>20a</b></figref> is a view of a bearing adapter for use in the assembly of <figref idref="f0024">Figure <b>19a</b></figref>;</li><li><figref idref="f0026">Figure <b>20b</b></figref> shows a top view of the bearing adapter of <figref idref="f0026">Figure <b>20a</b></figref>;</li><li><figref idref="f0026">Figure <b>20c</b></figref> shows a longitudinal cross-section of the bearing adapter of <figref idref="f0026">Figure <b>20a</b></figref>;</li><li><figref idref="f0027">Figure <b>21a</b></figref> shows an isometric view of a pad adapter for the assembly of <figref idref="f0024">Figure <b>19a</b></figref>;</li><li><figref idref="f0027">Figure <b>21b</b></figref> shows a top view of the pad adapter of <figref idref="f0027">Figure <b>21a</b></figref>;</li><li><figref idref="f0027">Figure <b>21c</b></figref> shows a side view of the pad adapter of <figref idref="f0027">Figure <b>21a</b></figref>;</li><li><figref idref="f0027">Figure <b>21d</b></figref> shows a half cross-section of the pad adapter of <figref idref="f0027">Figure <b>21a</b></figref>;</li><li><figref idref="f0027">Figure <b>21e</b></figref> shows an isometric view of a rocker for the pad adapter of <figref idref="f0027">Figure <b>21a</b></figref>;</li><li><figref idref="f0027">Figure <b>21f</b></figref> shows a top view of the rocker of <figref idref="f0027">Figure <b>21a</b></figref>;</li><li><figref idref="f0027">Figure <b>21g</b></figref> shows an end view of the rocker of <figref idref="f0027">Figure <b>21a</b></figref>;</li><li><figref idref="f0028">Figure <b>22a</b></figref> shows an end view of an alternate arrangement of wheelset to pedestal interface assembly arrangement to that of <figref idref="f0004">Figure <b>2a</b></figref><b>,</b> having mating bi-directionally arcuate rocking members, one being formed integrally as an outer portion of a bearing;</li><li><figref idref="f0029">Figure <b>22b</b></figref> shows a cross-section of the assembly of <figref idref="f0028">Figure <b>22a</b></figref> taken on <b>'22b - 22b'</b> of <figref idref="f0028">Figure <b>22a</b></figref><b>;</b></li><li><figref idref="f0028">Figure <b>22c</b></figref> shows a cross-section of the assembly of <figref idref="f0028">Figure <b>22a</b></figref> as viewed in the direction of arrows <b>'22c - 22c'</b> of <figref idref="f0029">Figure <b>22b</b></figref><b>;</b></li><li><figref idref="f0030">Figure <b>23a</b></figref> shows an end view of an alternate assembly to that of <figref idref="f0028">Figure <b>22a</b></figref> incorporating a unidirectionally fore-and-aft rocking member;</li><li><figref idref="f0030">Figure <b>23b</b></figref> shows a cross-sectional view taken on <b>'23b - 23b'</b> of <figref idref="f0030">Figure <b>23a</b></figref><b>;</b></li><li><figref idref="f0031">Figure <b>24a</b></figref> shows an isometric view of an alternate three piece truck to that of <figref idref="f0001">Figure <b>1a</b></figref>;</li><li><figref idref="f0031">Figure <b>24b</b></figref> shows a side view of the three piece truck of <figref idref="f0031">Figure <b>24a</b></figref><b>;</b></li><li><figref idref="f0031">Figure <b>24c</b></figref> shows a top view of half of the three piece truck of <figref idref="f0031">Figure <b>24b</b></figref><b>;</b></li><li><figref idref="f0031">Figure <b>24d</b></figref> shows a partial section of the truck of <figref idref="f0031">Figure <b>24b</b></figref> taken on <b>'24d - 24d'</b>;</li><li><figref idref="f0031">Figure <b>24e</b></figref> shows a partial isometric view of the truck bolster of the three piece truck of <figref idref="f0031">Figure <b>24a</b></figref> showing friction damper seats;</li><li><figref idref="f0032">Figure <b>24f</b></figref> shows a force schematic for four cornered damper arrangements generally, such as , for example, in the trucks of <figref idref="f0001">Figures <b>1a</b></figref><b>,</b><figref idref="f0003"><b>1f</b></figref><b>,</b> and <figref idref="f0031">Figure <b>24a</b></figref><b>;</b></li><li><figref idref="f0032">Figure <b>25a</b></figref> shows a side view of an alternate three piece truck to that of <figref idref="f0031">Figure <b>24a</b></figref><b>;</b></li><li><figref idref="f0032">Figure <b>25b</b></figref> shows a top view of half of the three piece truck of <figref idref="f0032">Figure <b>25a</b></figref><b>;</b> and</li><li><figref idref="f0032">Figure <b>25c</b></figref> shows a partial section of the truck of <figref idref="f0032">Figure <b>25a</b></figref> taken on <b>'25c - 25c';</b></li><li><figref idref="f0032">Figure <b>25d</b></figref> shows an exploded isometric view of the bolster and side frame assembly of <figref idref="f0032">Figure <b>25a</b></figref><b>,</b> in which horizontally acting springs drive constant force dampers;</li><li><figref idref="f0033">Figure <b>26a</b></figref> shows an alternate version of the bolster of <figref idref="f0031">Figure <b>24e</b></figref><b>,</b> with a double sized damper pocket for seating a large single wedge having a welded insert;</li><li><figref idref="f0033">Figure <b>26b</b></figref> shows an alternate dual wedge for a truck bolster like that of <figref idref="f0033">Figure <b>26a</b></figref><b>;</b></li><li><figref idref="f0034">Figure <b>27a</b></figref> shows an alternate bolster arrangement similar to that of <figref idref="f0008">Figure <b>5</b></figref><b>,</b> but having split wedges;</li><li><figref idref="f0034">Figure <b>27b</b></figref> shows a bolster similar to that of <figref idref="f0031">Figure <b>24a</b></figref><b>,</b> having a wedge pocket having primary and secondary angles and a split wedge arrangement for use therewith;</li><li><figref idref="f0034">Figure <b>27c</b></figref> shows an alternate stepped single wedge for the bolster of <figref idref="f0034">Figure <b>27b</b></figref><b>;</b></li><li><figref idref="f0033">Figure <b>28a</b></figref> shows an alternate bolster and wedge arrangement to that of <figref idref="f0022">Figure <b>17b</b></figref><b>,</b> having secondary wedge angles; and</li><li><figref idref="f0033">Figure <b>28b</b></figref> shows an alternate, split wedge arrangement for the bolster of <figref idref="f0033">Figure <b>28a</b></figref><b>.</b></li></ul>

Detailed Description of the Invention

The description that follows, and the embodiments described therein, are provided by way of illustration of an example, or examples, of particular embodiments of the principles of the present invention. These examples are provided for the purposes of explanation, and not of limitation, of those principles and of the invention. In the description, like parts are marked throughout the specification and the drawings with the same respective reference numerals. The drawings are not necessarily to scale and in some instances proportions may have been exaggerated in order more clearly to depict certain features of the invention.

In terms of general orientation and directional nomenclature, for each of the rail road car trucks described herein, the longitudinal direction is defined as being coincident with the rolling direction of the rail road car, or rail road car unit, when located on tangent (that is, straight) track. In the case of a rail road car having a center sill, the longitudinal direction is parallel to the center sill, and parallel to the side sills, if any. Unless otherwise noted, vertical, or upward and downward, are terms that use top of rail, TOR, as a datum. The term lateral, or laterally outboard, refers to a distance or orientation relative to the longitudinal centerline of the railroad car, or car unit. The term "longitudinally inboard", or "longitudinally outboard" is a distance taken relative to a mid-span lateral section of the car, or car unit. Pitching motion is angular motion of a railcar unit about a horizontal axis perpendicular to the longitudinal direction. Yawing is angular motion about a vertical axis. Roll is angular motion about the longitudinal axis.

This description relates to rail car trucks and truck components. Several AAR standard truck sizes are listed at page 711 in the 1997 <i>Car &amp; Locomotive Cyclopedia.</i> As indicated, for a single unit rail car having two trucks, a "40 Ton" truck rating corresponds to a maximum gross car weight on rail (GWR) of 142,000 lbs. Similarly, "50 Ton" corresponds to 177,000 lbs., "70 Ton" corresponds to 220,000 lbs., "100 Ton" corresponds to 263,000 lbs., and "125 Ton" corresponds to 315,000 lbs. In each case the load limit per truck is then half the maximum gross car weight on rail. Two other types of truck are the "110 Ton" truck for railcars having a 286,000 lbs. GWR and the "70 Ton Special" low profile truck sometimes used for auto rack cars. Given that the rail road car trucks described herein tend to have both longitudinal and transverse axes of symmetry, a description of one half of an assembly may generally also be intended to describe the other half as well, allowing for differences between right hand and left hand parts.

This application refers to friction dampers for rail road car trucks, and multiple friction damper systems. There are several types of damper arrangements, some being shown at pp. 715 - 716 of the 1997 <i>Car and Locomotive Cyclopedia,</i> those pages being incorporated herein by reference. Double damper arrangements are shown and described US Patent Application Publication No. <patcit id="pcit0003" dnum="US20030041772A1"><text>US 2003/0041772 A1,March 6, 2003</text></patcit>, entitled "Rail Road Freight Car With Damped Suspension", and also incorporated herein by reference. Each of the arrangements of dampers shown at pp. 715 to 716 of the <i>1997 Car and Locomotive Cyclopedia</i> can be modified to employ a four cornered, double damper arrangement of inner and outer dampers in conformity with the principles of aspects of the present invention.

Damper wedges are discussed herein. In terms of general nomenclature, the wedges tend to be mounted within an angled "bolster pocket" formed in an end of the truck bolster. In cross-section, each wedge may then have a generally triangular shape, one side of the triangle being, or having, a bearing face, a second side which might be termed the bottom, or base, forming a spring seat, and the third side being a sloped side or hypotenuse between the other two sides. The first side may tend to have a substantially planar bearing face for vertical sliding engagement against an opposed bearing face of one of the sideframe columns. The second face may not be a face, as such, but rather may have the form of a socket for receiving the upper end of one of the springs of a spring group. Although the third face, or hypotenuse, may appear to be generally planar, it may tend to have a slight crown, having a radius of curvature of perhaps 60". The crown may extend along the slope and may also extend across the slope. The end faces of the wedges may be generally flat, and may have a coating, surface treatment, shim, or low friction pad to give a smooth sliding engagement with the sides of the bolster pocket, or with the adjacent side of another independently slidable damper wedge, as may be.

During railcar operation, the sideframe may tend to rotate, or pivot, through a small range of angular deflection about the end of the truck bolster to yield wheel load equalisation. The slight crown on the slope face of the damper may tend to accommodate this pivoting motion by allowing the damper to rock somewhat relative to the generally inclined face of the bolster pocket while the planar bearing face remains in planar contact with the wear plate of the sideframe column. Although the slope face may have a slight crown, for the purposes of this description it will be described as the slope face or as the hypotenuse, and will be considered to be a substantially flat face as a general approximation.

In the terminology herein, wedges have a primary angle α, being the included angle between (a) the sloped damper pocket face mounted to the truck bolster, and (b) the side frame column face, as seen looking from the end of the bolster toward the truck center. In some embodiments, a secondary angle may be defined in the plane of angle α, namely a plane perpendicular to the vertical longitudinal plane of the (undeflected) side frame, tilted from the vertical at the primary angle. That is, this plane is parallel to the (undeflected) long axis of the truck bolster, and taken as if sighting along the back side (hypotenuse) of the damper. The secondary angle <b>β</b> is defined as the lateral rake angle seen when looking at the damper parallel to the plane of angle α As the suspension works in response to track perturbations, the wedge forces acting on the secondary angle <b>β</b> may tend to urge the damper either inboard or outboard according to the angle chosen.

General Description of Truck Features

<figref idref="f0001">Figures <b>1a</b></figref> and <figref idref="f0003"><b>1f</b></figref> provide examples of trucks <b>20</b> and <b>22</b> embodying an aspect of the invention. Trucks <b>20</b> and <b>22</b> of <figref idref="f0001">Figures <b>1a</b></figref> and <figref idref="f0003"><b>1f</b></figref> may have the same, or generally similar, features and similar construction, although they may differ in pendulum length, spring stiffness, wheelbase, window width and height, and damping arrangement. That is, truck <b>20</b> of <figref idref="f0003">Figure <b>1f</b></figref> may tend to have a longer wheelbase (from 73 inches to 86 inches, possibly between 80 - 84 inches for truck <b>20,</b> as opposed to a wheelbase of 63 - 73 inches for truck <b>22),</b> may tend to have a main spring group having a softer vertical spring rate, and a four cornered damper group that may have different primary and secondary angles on the damper wedges. Truck <b>20</b> may have a 5 x 3 spring group arrangement, while truck <b>22</b> may have a 3 x3 arrangement. While either truck may be suitable for a variety of general purpose uses, truck <b>20</b> may be optimized for carrying relatively low density, high value lading, such as automobiles or consumer products, for example, whereas truck <b>22</b> may be optimized for carrying denser semi-finished industrial goods, such as might be carried in rail road freight cars for transporting rolls of paper. The various features of the two truck types may be interchanged, and are intended to be illustrative of a wide range of truck types. Notwithstanding possible differences in size, generally similar features are given the same part numbers. Trucks <b>20</b> and <b>22</b> are symmetrical about both their longitudinal and transverse, or lateral, centreline axes. In each case, where reference is made to a sideframe, it will be understood that the truck has first and second sideframes, first and second spring groups, and so on.

Trucks <b>20</b> and <b>22</b> each have a truck bolster <b>24</b> and sideframes <b>26.</b> Each sideframe <b>26</b> has a generally rectangular window <b>28</b> that accommodates one of the ends <b>30</b> of the bolster <b>24.</b> The upper boundary of window <b>28</b> is defined by the sideframe arch, or compression member identified as top chord member <b>32,</b> and the bottom of window <b>28</b> is defined by a tension member identified as bottom chord <b>34.</b> The fore and aft vertical sides of window <b>28</b> are defined by sideframe columns <b>36.</b> The ends of the tension member sweep up to meet the compression member. At each of the swept-up ends of sideframe <b>26</b> there are sideframe pedestal fittings, or pedestal seats <b>38.</b> Each fitting <b>38</b> accommodates an upper fitting, which may be a rocker or a seat, as described and discussed below. This upper fitting, whichever it may be, is indicated generically as <b>40.</b> Fitting <b>40</b> engages a mating fitting <b>42</b> of the upper surface of a bearing adapter <b>44.</b> Bearing adapter <b>44</b> engages a bearing <b>46</b> mounted on one of the ends of one of the axles <b>48</b> of the truck adjacent one of the wheels <b>50.</b> A fitting <b>40</b> is located in each of the fore and aft pedestal fittings <b>38,</b> the fittings <b>40</b> being longitudinally aligned so the sideframe can swing sideways relative to the truck's rolling direction.

The relationship of the mating fittings <b>40</b> and <b>42</b> is described at greater length below. The relationship of these fittings determines part of the overall relationship between an end of one of the axles of one of the wheelsets and the sideframe pedestal. That is, in determining the overall response, the degrees of freedom of the mounting of the axle end in the sideframe pedestal involve a dynamic interface across an assembly of parts, such as may be termed a wheelset to sideframe interface assembly, that may include the bearing, the bearing adapter, an elastomeric pad, if used, a rocker if used, and the pedestal seat mounted in the roof of the sideframe pedestal. Several different embodiments of this wheelset to sideframe interface assembly are described below. To the extent that bearing <b>46</b> has a single degree of freedom, namely rotation about the wheelshaft axis, analysis of the assembly can be focused on the bearing to pedestal seat interface assembly, or on the bearing adapter to pedestal seat interface assembly. For the purposes of this description, items <b>40</b> and <b>42</b> are intended generically to represent the combination of features of a bearing adapter and pedestal seat assembly defining the interface between the roof of the sideframe pedestal and the bearing adapter, and the six degrees of freedom of motion at that interface, namely vertical, longitudinal and transverse translation (i.e., translation in the z, x, and y directions) and pitching, rolling, and yawing (i.e., rotational motion about the y, x, and z axes respectively) in response to dynamic inputs.

The bottom chord or tension member of sideframe <b>26</b> may have a basket plate, or lower spring seat <b>52</b> rigidly mounted thereto. Although trucks <b>22</b> may be free of unsprung lateral cross-bracing, whether in the nature of a transom or lateral rods, in the event that truck <b>22</b> is taken to represent a "swing motion" truck with a transom or other cross bracing, the lower rocker platform of spring seat <b>52</b> may be mounted on a rocker, to permit lateral rocking relative to sideframe <b>26.</b> Spring seat <b>52</b> may have retainers for engaging the springs <b>54</b> of a spring set, or spring group, <b>56,</b> whether internal bosses, or a peripheral lip for discouraging the escape of the bottom ends of the springs. The spring group, or spring set <b>56,</b> is captured between the distal end <b>30</b> of bolster <b>24</b> and spring seat <b>52,</b> being placed under compression by the weight of the rail car body and lading that bears upon bolster <b>24</b> from above.

Bolster <b>24</b> has double, inboard and outboard, bolster pockets <b>60, 62</b> on each face of the bolster at the outboard end (i.e., for a total of 8 bolster pockets per bolster, 4 at each end). Bolster pockets <b>60, 62</b> accommodate fore and aft pairs of first and second, laterally inboard and laterally outboard friction damper wedges <b>64, 66</b> and <b>68, 70,</b> respectively. Each bolster pocket <b>60, 62</b> has an inclined face, or damper seat <b>72,</b> that mates with a similarly inclined hypotenuse face <b>74</b> of the damper wedge, <b>64, 66, 68</b> and <b>70.</b> Wedges <b>64, 66</b> each sit over a first, inboard corner spring <b>76, 78,</b> and wedges <b>68, 70</b> each sit over a second, outboard corner spring <b>80, 82.</b> Angled faces <b>74</b> of wedges <b>64, 66</b> and <b>68, 70</b> ride against the angled faces of respective seats <b>72.</b>

A middle end spring <b>96</b> bears on the underside of a land <b>98</b> located intermediate bolster pockets <b>60</b> and <b>62.</b> The top ends of the central row of springs, <b>100,</b> seat under the main central portion <b>102</b> of the end of bolster <b>24.</b> In this four corner arrangement, each damper is individually sprung by one or another of the springs in the spring group. The static compression of the springs under the weight of the car body and lading tends to act as a spring loading to bias the damper to act along the slope of the bolster pocket to force the friction surface against the sideframe. Friction damping is provided when the vertical sliding faces <b>90</b> of the friction damper wedges <b>64, 66</b> and <b>68, 70</b> ride up and down on friction wear plates <b>92</b> mounted to the inwardly facing surfaces of sideframe columns <b>36.</b> In this way the kinetic energy of the motion is, in some measure, converted through friction to heat. This friction may tend to damp out the motion of the bolster relative to the sideframes. When a lateral perturbation is passed to wheels <b>50</b> by the rails, rigid axles <b>48</b> may tend to cause both sideframes <b>26</b> to deflect in the same direction. The reaction of sideframes <b>26</b> is to swing, like pendula, on the upper rockers. The weight of the pendulum and the reactive force arising from the twisting of the springs may then tend to urge the sideframes back to their initial position. The tendency to oscillate harmonically due to track perturbations may tend to be damped out by the friction of the dampers on the wear plates <b>92.</b>

As compared to a bolster with single dampers, such as may be mounted on the sideframe centerline as shown in <figref idref="f0002">Figure 1e</figref>, for example, the use of doubled dampers such as spaced apart pairs of dampers <b>64, 68</b> may tend to give a larger moment arm, as indicated by dimension <b>"2M"</b> in <figref idref="f0002">Figure <b>1d</b></figref>, for resisting parallelogram deformation of truck <b>22</b> more generally. Use of doubled dampers may yield a greater restorative "squaring" force to return the truck to a square orientation than for a single damper alone with the restorative bias, namely the squaring force, increasing with increasing deflection. That is, in parallelogram deformation, or lozenging, the differential compression of one diagonal pair of springs (e.g., inboard spring <b>76</b> and outboard spring 82 may be more pronouncedly compressed) relative to the other diagonal pair of springs (e.g., inboard spring <b>78</b> and outboard spring <b>80</b> may be less pronouncedly compressed than springs <b>76</b> and <b>82)</b> tends to yield a restorative moment couple acting on the sideframe wear plates. This moment couple tends to rotate the sideframe in a direction to square the truck, (that is, in a position in which the bolster is perpendicular, or "square", to the sideframes). As such, the truck is able to flex, and when it flexes the dampers co-operate in acting as biased members working between the bolster and the side frames to resist parallelogram, or lozenging, deformation of the side frame relative to the truck bolster and to urge the truck back to the non-deflected position.

The foregoing explanation has been given in the context of trucks <b>20</b> and <b>22,</b> each of which has a spring group that has three rows facing the sideframe columns. The restorative moment couple of a four-cornered damper layout can also be explained in the context of a truck having a 2 row spring group arrangement facing the dampers, as in truck <b>400</b> of <figref idref="f0019">Figures <b>14a</b> to <b>14e</b></figref><b>.</b> For the purposes of conceptual visualisation, the normal force on the friction face of any of the dampers can be taken as a pressure field whose effect can be approximated by a point load acting at the centroid of the pressure field and whose magnitude is equal to the integrated value of the pressure field over its area. The center of this distributed force, acting on the inboard friction face of wedge <b>440</b> against column <b>428</b> can be thought of as a point load offset transversely relative to the diagonally outboard friction face of wedge <b>443</b> against column <b>430</b> by a distance that is nominally twice dimension <b>'L'</b> shown in the conceptual sketch of <figref idref="f0001 f0002 f0003">Figure <b>1k.</b></figref> In the example of <figref idref="f0019">Figure <b>14a</b></figref><b>,</b> this distance, <b>2L,</b> is about one full diameter of the large spring coils in the spring set. The restoring moment in such a case would be, conceptually, <b>M_R</b> = [(<b>F</b>₁ + <b>F</b>₃) - (<b>F</b>₂ + <b>F</b>₄)]<b>L.</b> This may be expressed <b>M_R</b> = 4<b>k</b>_cTan(<b>ε</b>)Tan(<b>θ</b>)<b>L,</b> where <b>θ</b> is the primary angle of the damper (generally illustrated as <b>α</b> herein), and <b>k_c</b> is the vertical spring constant of the coil upon which the damper sits and is biased.

In the various arrangements of spring groups 2 x 4, 3 x 3, 3:2:3 or 3 x 5 group, dampers may be mounted over each of four corner positions. The portion of spring force acting under the damper wedges may be in the 25 - 50 % range for springs of equal stiffness. If not of equal stiffness, the portion of spring force acting under the dampers may be in the range of perhaps 20 % to 35 %. The coil groups can be of unequal stiffness if inner coils are used in some springs and not in others, or if springs of differing spring constant are used.

In the view of the present inventors, it may be that an enhanced tendency to encourage squareness at the bolster to sideframe interface (i.e., through the use of four cornered damper groups) may tend to reduce reliance on squareness at the pedestal to wheelset axle interface. This, in turn, may tend to provide an opportunity to employ a torsionally compliant (about the vertical axis) axle to pedestal interface assembly, and to permit a measure of self steering.

The bearing plate, namely wear plate <b>92</b> (<figref idref="f0001">Figure <b>1a</b></figref>) is significantly wider than the through thickness of the sideframes more generally, as measured, for example, at the pedestals, and may tend to be wider than has been conventionally common. This additional width corresponds to the additional overall damper span width measured fully across the damper pairs, plus lateral travel as noted above, typically allowing 1 ½ (+/-) inches of lateral travel of the bolster relative to the sideframe to either side of the undeflected central position. That is, rather than having the width of one coil, plus allowance for travel, plate <b>92</b> may have the width of three coils, plus allowance to accommodate 1½ (+/-) inches of travel to either side for a total, double amplitude travel of 3" (+/-). Bolster <b>24</b> has inboard and outboard gibs <b>106, 108</b> respectively, that bound the lateral motion of bolster <b>24</b> relative to sideframe columns <b>36.</b> This motion allowance may be in the range of +/-1 ⅛ to 1 ¾ in., and may be in the range of 1 3/16 to 1 9/16 in., and can be set, for example, at 1 ½ in. or 1 ¼ in. of lateral travel to either side of a neutral, or centered, position when the sideframe is undeflected.

The lower ends of the springs of the entire spring group, identified generally as <b>58,</b> seat in lower spring seat <b>52.</b> Lower spring seat <b>52</b> may be laid out as a tray with an upturned rectangular peripheral lip. Although truck <b>22</b> employs a spring group in a 3 x 3 arrangement, this is intended to be generic, and to represent a range of variations. They may represent 3 x 5, 2 x 4, 3:2:3 or 2:3:2 arrangement, or some other, and may include a hydraulic snubber, or such other arrangement of springs may be appropriate for the given service for the railcar for which the truck is intended.

Figures 2a - 2g

The rocking interface surface of the bearing adapter might have a crown, or a concave curvature, like a swing motion truck, by which a rolling contact on the rocker permits lateral swinging of the side frame. The bearing adapter to pedestal seat interface might also have a fore-and-aft curvature, whether a crown or a depression, and that, for a given vertical load, this crown or depression might tend to present a more or less linear resistance to deflection in the longitudinal direction, much as a spring or elastomeric pad might do.

For surfaces in rolling contact on a compound curved surface (i.e., having curvatures in two directions) as shown and described herein, the vertical stiffness may be approximated as infinite (i.e. very large as compared to other stiffnesses); the longitudinal stiffness in translation at the point of contact can also be taken as infinite, the assumption being that the surfaces do not slip; the lateral stiffness in translation at the point of contact can be taken as infinite, again, provided the surfaces do not slip. The rotational stiffness about the vertical axis may be taken as zero or approximately zero. By contrast, the angular stiffnesses about the longitudinal and transverse axes are non-trivial. The lateral angular stiffnesses may tend to determine the equivalent pendulum stiffnesses for the sideframe more generally.

The stiffness of a pendulum is directly proportional to the weight on the pendulum. Similarly, the drag on a rail car wheel, and the wear to the underlying track structure, is a function of the weight borne by the wheel. For this reason, the desirability of self steering may be greatest for a fully laden car, and a pendulum may tend to maintain a general proportionality between the weight borne by the wheel and the stiffness of the self-steering mechanism as the lading increases.

Truck performance may vary with the friction characteristics of the damper surfaces. Dampers have been used that have tended to employ dampers in which the dynamic and static coefficients of friction may have been significantly different, yielding a stick-slip phenomenon that may not have been entirely advantageous. It may be advantageous to combine the feature of a self-steering capability with dampers that have a reduced tendency to stick-slip operation.

Furthermore, while bearing adapters may be formed of relatively low cost materials, such as cast iron, in some embodiments an insert of a different material may be used for the rocker. Further it may be advantageous to employ a member that may tend to center the rocker on installation, and that may tend to perform an auxiliary centering function to tend to urge the rocker to operate from a desired minimum energy position.

<figref idref="f0004 f0005">Figures <b>2a - 2g</b></figref> show an embodiment of bearing adapter and pedestal seat assembly. Bearing adapter <b>44</b> has a lower portion <b>112</b> that is formed to accommodate, and to seat upon, bearing <b>46,</b> that is itself mounted on the end of a shaft, namely an end of axle <b>48.</b> Bearing adapter <b>44</b> has an upper portion <b>114</b> that has a centrally located, upwardly protruding fitting in the nature of a male bearing adapter interface portion <b>116.</b> A mating fitting, in the nature of a female rocker seat interface portion <b>118</b> is rigidly mounted within the roof <b>120</b> of the sideframe pedestal. To that end, laterally extending lugs <b>122</b> are mounted centrally with respect to pedestal roof <b>120.</b> The upper fitting <b>40,</b> whichever type it may be, has a body that may be in the form of a plate <b>126</b> having, along its longitudinally extending, lateral margins a set of upwardly extending lugs or ears, or tangs <b>124</b> separated by a notch, that bracket, and tightly engage lugs <b>122,</b> thereby locating upper fitting <b>40</b> in position, with the back of the plate <b>126</b> of fitting <b>40</b> abutting the flat, load transfer face of roof <b>120.</b> Upper fitting <b>40</b> may be a pedestal seat fitting with a hollowed out female bearing surface, namely portion <b>118.</b> As shown in <figref idref="f0005">Figure 2g</figref>, when the sideframes are lowered over the wheel sets, the end reliefs, or channels <b>128</b> lying between the bearing adapter corner abutments <b>132</b> seat between the respective side frame pedestal jaws <b>130.</b> With the sideframes in place, bearing adapter <b>44</b> is thus captured in position with the male and female portions <b>(116</b> and <b>118)</b> of the adapter interface in mating engagement.

Male portion <b>116</b> (<figref idref="f0005">Figure <b>2d</b></figref>) has been formed to have a generally upwardly facing surface <b>142</b> that has both a first curvature <b>r₁</b> to permit rocking in the longitudinal direction, and a second curvature r₂ (<figref idref="f0004">Figure <b>2c</b></figref>) to permit rocking (i.e., swing motion of the sideframe) in the transverse direction. Similarly, in the general case, female portion <b>118</b> has a surface having a first radius of curvature <b>R₁</b> in the longitudinal direction, and a second radius of curvature <b>R₂</b> in the transverse direction. The engagement of <b>r₁</b> with <b>R₁</b> may tend to permit a rocking motion in the longitudinal direction, with resistance to rocking displacement being proportional to the weight on the wheel. That is to say, the resistance to angular deflection is proportional to weight rather than being a fixed spring constant. This may tend to yield passive self-steering in both the light car and fully laden conditions. This relationship is shown in <figref idref="f0005">Figures <b>2d</b> and <b>2e</b>. Figure <b>2d</b></figref> shows the centered, or at rest, non-deflected position of the longitudinal rocking elements. <figref idref="f0005">Figure <b>2e</b></figref> shows the rocking elements at their condition of maximum longitudinal deflection. <figref idref="f0005">Figure <b>2d</b></figref> represents a local, minimum potential energy condition for the system. <figref idref="f0005">Figure <b>2e</b></figref> represents a system in which the potential energy has been increased by virtue of the work done by force <b>F</b> acting longitudinally in the horizontal plane through the center of the axle and bearing, <b>C_B.,</b> which will tend to yield an incremental increase in the height of the pedestal. Put differently, as the axle is urged to deflect by the force, the rocking motion may tend to raise the car, and thereby to increase its potential energy.

The limit of travel in the longitudinal direction is reached when the end face <b>134</b> of bearing adapter <b>44</b> extending between corner abutments <b>132,</b> contacts one or another of travel limiting abutment faces <b>136</b> of the thrust blocks of jaws <b>130.</b> In general, the deflection may be measured either by the angular displacement of the axle centreline, θ₁, or by the angular displacement of the rocker contact point on radius <b>r₁,</b> shown as θ₂. End face <b>134</b> of bearing adapter <b>44</b> is planar, and is relieved, or inclined, at an angle <b>η</b> from the vertical. As shown in <figref idref="f0005">Figure <b>2g</b></figref><b>,</b> abutment face <b>136</b> may have a round, cylindrical arc, with the major axis of the cylinder extending vertically. A typical maximum radius <b>R₃</b> for this surface is 34 inches. When bearing adapter <b>44</b> is fully deflected through angle <b>η</b> end face <b>134</b> is intended to meet abutment face <b>136</b> in line contact. When this occurs, further longitudinal rocking motion of the male surface (of portion <b>116)</b> against the female surface (of portion <b>118)</b> is inhibited. Thus jaws <b>130</b> constrain the arcuate deflection of bearing adapter <b>44</b> to a limited range. A typical range for <b>η</b> might be about 3 degrees of arc. A typical maximum value of <b>δ_long</b> may be about +/- 3/16" to either side of the vertical, at rest, center line.

Similarly, as shown in <figref idref="f0004">Figures <b>2b</b> and <b>2c</b></figref><b>,</b> in the transverse direction, the engagement <b>of r₂</b> with <b>R₂</b> may tend to permit lateral rocking motion, as may be in the manner of a swing motion truck. <figref idref="f0004">Figure <b>2b</b></figref> shows a centered, at rest, minimum potential energy position of the lateral rocking system. <figref idref="f0004">Figure <b>2c</b></figref> shows the same system in a laterally deflected condition. In this instance <b>δ₂</b> is roughly (<b>L_pendulum - r₂</b>)Sin<b>ϕ,</b> where, for small angles Sin<b>ϕ</b> is approximately equal to <b>ϕ</b>. <b>L_pendulum</b> may be taken as the at rest difference in height between the center of the bottom spring seat, <b>52,</b> and the contact interface between the male and female portions <b>116</b> and <b>118.</b>

When a lateral force is applied at the centerplate of the truck bolster, a reaction force is, ultimately, provided at the meeting of the wheels with the rail. The lateral force is transmitted from the bolster into the main spring groups, and then into a lateral force in the spring seats to deflect the bottom of the pendulum. The reaction is carried to the bearing adapter, and hence into the top of the pendulum. The pendulum will then deflect until the weight on the pendulum, multiplied by the moment arm of the deflected pendulum is sufficient to balance the moment of the lateral moment couple acting on the pendulum.

This bearing adapter to pedestal seat interface assembly is biased by gravity acting on the pendulum toward a central, or "at rest" position, where there is a local minimum of the potential energy in the system. The fully deflected position shown in <figref idref="f0004">Figure <b>2c</b></figref> may correspond to a deflection from vertical of the order of less than 10 degrees (and preferably less than 5 degrees) to either side of center, the actual maximum being determined by the spacing of gibbs <b>106</b> and <b>108</b> relative to plate <b>104.</b> Although in general <b>R₁</b> and <b>R₂</b> may differ, so the female surface is an outside section of a torus, it may be desirable, for <b>R₁</b> and <b>R₂</b> to be the same, i.e., so that the bearing surface of the female fitting is formed as a portion of a spherical surface, having neither a maj or nor a minor axis, but merely being formed on a spherical radius. <b>R₁</b> and <b>R₂</b> give a self-centering tendency. That tendency may be quite gentle. Further, and again in the general condition, the smallest of <b>R₁</b> and <b>R₂</b> may be equal to or larger than the largest of <b>r₁</b> and <b>r₂.</b> If so, then the contact point may have little, if any, ability to transmit torsion acting about an axis normal to the rocking surfaces at the point of contact, so the lateral and longitudinal rocking motions may tend to be torsionally de-coupled, and hence it may be said that relative to this degree of freedom (rotation about the vertical, or substantially vertical axis normal to the rocking contact interface surfaces) the interface is torsionally compliant (that is, the resistance to torsional deflection about the axis through the surfaces at the point of contact may tend to be much smaller than, for example, resistance to lateral angular deflection). For small angular deflections, the torsional stiffness about the normal axis at the contact point, this condition may sometimes be satisfied even where the smaller of the female radii is less than the largest male radius. Although it is possible for <b>r₁</b> and <b>r₂</b> to be the same, such that the crowned surface of the bearing adapter (or the pedestal seat, if the relationship is inverted) is a portion of a spherical surface, in the general case <b>r₁</b> and <b>r₂</b> may be different, with <b>r₁</b> perhaps tending to be larger, possibly significantly larger, than <b>r₂.</b> In general, whether or not <b>r₁</b> and <b>r₂</b> are equal, <b>R₁</b> and <b>R₂</b> may be the same or different. Where <b>r₁</b> and <b>r₂</b> are different, the male fitting engagement surface may be a section of the surface of a torus. It may also be noted that, provided the system may tend to return to a local minimum energy state (i.e., that is self-restorative in normal operation) in the limit either or both of <b>R₁</b> and <b>R₂</b> may be infinitely large such that either a cylindrical section is formed or, when both are infinitely large, a planar surface may be formed. In the further alternative, it may be that <b>r₁</b> = <b>r₂,</b> and <b>R₁</b> = <b>R₂.</b> In one embodiment <b>r₁</b> may be the same as <b>r₂,</b> and may be about 40 inches (+/- 5") and <b>R₁</b> may the same as <b>R₂,</b> and both may be infinite such that the female surface is planar.

Other embodiments of rocker geometry may be considered. In one embodiment <b>R₁</b> = <b>R₂</b> =15 inches, <b>r₁</b>, = 8 ⅝ inches and <b>r₂</b> = 5". In another embodiment, <b>R₁</b> = <b>R₂</b> = 15 inches, and <b>r₁</b> = 10" and <b>r₂</b> = 8 ⅝" (+/-). In another embodiment <b>r₁</b> = 8 ⅝, <b>r₂</b> = 5", <b>R₁</b> = <b>R₂</b> =12" in still another embodiment <b>r₁</b> = 12 ½", <b>r₂</b> = 8 ⅝ and <b>R₁</b> = <b>R₂</b> =15". In another embodiment <b>R₁ = R₂</b> =∞ and <b>r₁</b> = <b>r₂</b> = 40".

The radius of curvature of the male longitudinal rocker, <b>r₁,</b> may be less than 60 inches, and may lie in the range of 5 to 50 inches, may lie in the range of 8 to 40 inches, and may be about 15 inches. <b>R₁</b> may be infinite, or may be less than 100 inches, and may be in the range of 10 to 60 inches, or in the narrower range of 12 to 40 inches, and may be in the range of 11/10 to 4 times the size of <b>r₁.</b>

The radius of curvature of the male lateral rocker, <b>r₂,</b> may be between 30 and 50 inches. Alternatively in another type of truck, <b>r₂,</b> may be less than about 25 or 30 in., and may lie in the range of about 5 to 20 inches. <b>r₂</b> may lie in the range of about 8 to 16 inches, and may be about 10 inches. Where line contact rocking motion is used, <b>r₂</b> may perhaps be somewhat smaller than otherwise, perhaps in the range of 3 to 10 inches, and perhaps being about 5 inches.

<b>R₂</b> may be less than 60 inches, and may be less than about 25 or 30 inches, then being less than half the 60 inch crown radius noted above. Alternatively, <b>R₂</b> may lie in the range of 6 to 40 inches, and may lie in the range of 5 to 15 inches in the case of rolling line contact. <b>R₂</b> may be between 1 ½ to 4 times as large as <b>r₂.</b> In one embodiment <b>R₂</b> may be roughly twice as large as <b>r₂,</b> (+/- 20 %). Where line contact is employed, R2 may be in the range of 5 to 20 inches, or more narrowly, 8 to 14 inches.

Where a spherical male rocker is used on a spherical female cap, in some embodiments the male radius may be in the range of 8 -13 in., and may be about 9 in.; the female radius may be in the range of 11-16 in., and may be about 12 in. Where a torus, or elliptical surface is employed, in one embodiment the lateral male radius may be about 7 in., the longitudinal male radius may be about 10 inches, the lateral female radius may be about 12 in. and the longitudinal female radius may be about 15 in. Where a flat female rocker surface is used, and a male spherical surface is used, the male radius of curvature may be in the range of about 20 to about 50 in., and may lie in the narrower range of 30 to 40 in.

Many combinations are possible, depending on loading, intended use, and rocker materials. In each case the mating male and female rocker surfaces may tend to be chosen to yield a physically reasonable pairing in terms of expected loading, anticipated load history, and operational life. These may vary.

The rocker surfaces herein may tend to be formed of a relatively hard material, which may be a metal or metal alloy material, such as a steel or a material of comparable hardness and toughness. Such materials may have elastic deformation at the location of rocking contact in a manner analogous to that of journal or ball bearings. Nonetheless, the rockers may be taken as approximating the ideal rolling point or line contact (as may be) of infinitely stiff members. This is to be distinguished from materials in which deflection of an elastomeric element be it a pad, or block, of whatever shape, may be intended to determine a characteristic of the dynamic or static response of the element.

In one embodiment the lateral rocking constant for a light car may be in the range of about 48,000 to 130,000 in-lbs per radian of angular deflection of the side frame pendulum, or, 260,000 to 700,000 in-lbs per radian for a fully laded car, or more generically, about 0.95 to 2.6 in-lbs per radian per pound of weight borne by the pendulum. Alternatively, for a light (i.e., empty) car the stiffness of the pendulum may be in the range 3,200 to 15,000 lbs per inch, and 22,000 to 61,000 Ibs per inch for a fully laden 110 ton truck, or, more generically, in the range of 0.06 to 0.160 lbs per inch of lateral deflection per pound weight borne by the pendulum, as measured at the bottom spring seat.

The male and female surfaces may be inverted, such that the female engagement surface is formed on the bearing adapter, and the male engagement surface is formed on the pedestal seat. It is a matter of terminology which part is actually the "seat", and which is the "rocker". Sometimes the seat may be assumed to be the part that has the larger radius, and which is usually thought of as being the stationary reference, while the rocker is taken to be the part with the smaller radius, that "rocks" on the stationary seat. However, this is not always so. At root, the relationship is of mating parts, whether male or female, and there is relative motion between the parts, or fittings, whether the fittings are called a "seat" or a "rocker". The fittings mate at a force transfer interface. The force transfer interface moves as the parts that co-operate to define the rocking interface rock on each other, whichever part may be, nominally, the male part or the female part. One of the mating parts or surfaces is part of the bearing adapter, and another is part of the pedestal. There may be only two mating surfaces, or there may be more than two mating surfaces in the overall assembly defining the dynamic interface between the bearing adapter and the pedestal fitting, or pedestal seat, however it may be called.

Both female radii <b>R₁</b> and <b>R₂</b> may not be on the same fitting, and both male radii r₁ and r₂ may not be on the same fitting. That is, they may be combined to form saddle shaped fittings in which the bearing adapter has an upper surface that has a male fitting in the nature of a longitudinally extending crown with a laterally extending axis of rotation, having the radius of curvature is <b>r₁,</b> and a female fitting in the nature of a longitudinally extending trough having a lateral radius of curvature <b>R₂.</b> Similarly, the pedestal seat fitting may have a downwardly facing surface that has a transversely extending trough having a longitudinally oriented radius of curvature <b>R₁,</b> for engagement with <b>r₁</b> of the crown of the bearing adapter, and a longitudinally running, downwardly protruding crown having a transverse radius of curvature <b>r₂</b> for engagement with <b>R₂</b> of the trough of the bearing adapter.

In a sense, a saddle shaped surface is both a seat and a rocker, being a seat in one direction, and a rocker in the other. As noted above, the essence is that there are two small radii, and two large (or possibly even infinite) radii, and the surfaces form a mating pair that engage in rolling contact in both the lateral and longitudinal directions, with a central local minimum potential energy position to which the assembly is biased to return. It may also be noted that the saddle surfaces can be inverted such that the bearing adapter has <b>r₂</b> and <b>R₁,</b> and the pedestal seat fitting has <b>r₁</b> and <b>R₂.</b> In either case, the smallest <b>of R₁</b> and <b>R₂</b> may be larger than, or equal to, the largest of <b>r₁</b> and <b>r₂,</b> and the mating saddle surfaces may tend to be torsionally uncoupled as noted above.

Figures <b>3a</b>

<figref idref="f0006">Figure <b>3a</b></figref> shows an alternate embodiment of wheelset to sideframe interface assembly, indicated most generally as <b>150.</b> In this example it may be understood that the pedestal region of sideframe <b>151,</b> as shown in <figref idref="f0006">Figure <b>3a</b></figref>, is substantially similar to those shown in the previous examples, and may be taken as being the same except insofar as may be noted. Similarly, bearing <b>152</b> may be taken as representing the location of the end of a wheelset more generally, with the wheelset to sideframe interface assembly including those items, members or elements that are mounted between bearing <b>152</b> and sideframe <b>151.</b> Bearing adapter <b>154</b> may be generally similar to bearing adapter <b>44</b> in terms of its lower structure for seating on bearing <b>152.</b> As with the bodies of the other bearing adapters described herein, the body of bearing adapter <b>154</b> may be a casting or a forging, or a machined part, and may be made of a material that may be a relatively low cost material, such as cast iron or steel, and may be made in generally the same manner as bearing adapters have been made heretofore. Bearing adapter <b>154</b> may have a bi-directional rocker <b>153</b> employing a compound curvature of first and second radii of curvature according to one or another of the possible combinations of male and female radii of curvature discussed herein. Bearing adapter <b>154</b> may differ from those described above in that the central body portion 155 of the adapter has been trimmed to be shorter longitudinally, and the inside spacing between the corner abutment portions has been widened somewhat, to accommodate the installation of an auxiliary centering device, or centering member, or centrally biased restoring member in the nature of, for example, elastomeric bumper pads, such as those identified as resilient pads, or members <b>156.</b> Members <b>156</b> may be considered a form of restorative centering element, and may also be termed "snubbers" or "bumper" pads. A pedestal seat fitting having a mating rocking surface for permitting lateral and longitudinal rocking, is identified as <b>158.</b> As with the other pedestal seat fittings shown and described herein, fitting <b>158</b> may be made of a hard metal material, which may be a grade of steel. The engagement of the rocking surfaces may, again, tend to have low resistance to torsion about predominantly vertical axis through the point of contact.

Figure <b>3b</b>

In <figref idref="f0006">Figure 3b</figref>, a bearing adapter <b>160</b> is substantially similar to bearing adapter <b>154,</b> but differs in having a central recess, socket, cavity or accommodation, indicated generally as <b>161</b> for receiving an insert identified as a first, or lower, rocker member <b>162.</b> As with bearing adapter <b>154,</b> the main, or central portion of the body <b>159</b> of bearing adapter <b>160</b> may be of shorter longitudinal extent than might otherwise be the case, being truncated, or relieved, to accommodate resilient members <b>156.</b>

Accommodation <b>161</b> may have a plan view form whose periphery may include one or more keying, or indexing, features or fittings, of which cusps <b>163</b> may be representative. Cusps <b>163</b> may receive mating keying, or indexing, features or fittings of rocker member <b>162,</b> of which lobes <b>164</b> may be taken as representative examples. Cusps <b>163</b> and lobes <b>164</b> may fix the angular orientation of the lower, or first, rocker member <b>162</b> such that the appropriate radii of curvature may be presented in each of the lateral and longitudinal directions. For example, cusps <b>163</b> may be spaced unequally about the periphery of accommodation <b>161</b> (with lobes <b>164</b> being correspondingly spaced about the periphery of the insert member <b>162)</b> in a specific spacing arrangement to prevent installation in an incorrect orientation, (such as 90 degrees out of phase). For example, one cusp may be spaced 80 degrees of arc about the periphery from one neighbouring cusp, and 100 degrees of arc from another neighbouring cusp, and so on to form a rectangular pattern. Many variations are possible.

While body <b>159</b> of bearing adapter <b>160</b> may be made of cast iron or steel, the insert, namely first rocker member <b>162,</b> may be made of a different material. That different material may present a hardened metal rocker surface such as may have been manufactured by a different process. For example, the insert, member <b>162,</b> may be made of a tool steel, or of a steel such as may be used in the manufacture of ball bearings. Furthermore, upper surface <b>165</b> of insert member <b>162,</b> which includes that portion that is in rocking engagement with the mating pedestal seat <b>168,</b> may be machined or otherwise formed to a high degree of smoothness, akin to a ball bearing surface, and may be heat treated, to give a finished bearing part.

Similarly, pedestal seat <b>168</b> may be made of a hardened material, such as a tool steel or a steel from which bearings are made, formed to a high level of smoothness, and heat treated as may be appropriate, having a surface formed to mate with surface <b>165</b> of rocker member <b>162.</b> Alternatively, pedestal seat <b>168</b> may have an accommodation indicated as <b>167,</b> and an insert member, identified as upper or second rocker member <b>166,</b> analogous to accommodation <b>161</b> and insert member <b>162,</b> with keying or indexing such as may tend to cause the parts to seat in the correct orientation. Member <b>166</b> may be formed of a hard material in a manner similar to member <b>162,</b> and may have a downward facing rocking surface <b>157,</b> which may be machined or otherwise formed to a high degree of smoothness, akin to a ball or roller bearing surface, and may be heat treated, to give a finished bearing part surface for mating, rocking engagement with surface <b>165.</b> Where rocker member <b>162</b> has both male radii, and the female radii of curvature are both infinite such that the female surface is planar, a wear member having a planar surface such as a spring clip may be mounted in a sprung interference fit in the pedestal roof in lieu of pedestal seat <b>168.</b> In one embodiment, the spring clip may be a clip on "Dyna-Clip" (t.m.) pedestal roof wear plate such as supplied by TransDyne Inc. Such a clip is shown in an isometric view in <figref idref="f0011">Figure <b>8a</b></figref> as item <b>354.</b>

Figure <b>3e</b>

<figref idref="f0007">Figure <b>3e</b></figref> shows an alternate embodiment of wheelset to sideframe interface assembly, indicated generally as <b>170.</b> Assembly <b>170</b> may include a bearing adapter <b>171,</b> a pair of resilient members <b>156,</b> a rocking assembly that may include a boot, resilient ring or retainer, <b>172,</b> a first rocker member <b>173,</b> and a second rocker member <b>174.</b> A pedestal seat may be provided to mount in the roof of the pedestal as described above, or second rocker member <b>174</b> may mount directly in the pedestal roof.

Bearing adapter <b>171</b> is generally similar to bearing adapter <b>44,</b> or <b>154,</b> in terms of its lower structure for seating on bearing <b>152.</b> The body of bearing adapter <b>171</b> may be a casting or a forging, or a machined part, and may be made of a material that may be a relatively low cost material, such as cast iron or steel. Bearing adapter <b>171</b> may be provided with a central recess, socket, cavity or accommodation, indicated generally as <b>176,</b> for receiving rocker member <b>173</b> and rocker member <b>174,</b> and retainer <b>172.</b> The ends of the main portion of the body of bearing adapter <b>171</b> may be of relatively short extent to accommodate resilient members <b>156.</b> Accommodation <b>176</b> may have the form of a circular opening, that may have a radially inwardly extending flange <b>177,</b> whose upwardly facing surface <b>178</b> defines a circumferential land upon which to seat first rocker member <b>173.</b> Flange <b>177</b> may also include drain holes <b>178,</b> such as may be 4 holes formed on 90 degree centers, for example. Rocker member <b>173</b> has a spherical engagement surface. First rocker member <b>173</b> may include a thickened central portion, and a thinner radially distant peripheral portion, having a lower radial edge, or margin, or land, for seating upon, and for transferring vertical loads into, flange <b>177.</b> In an alternate embodiment, a non-galling, relatively soft annular gasket, or shim, whether made of a suitable brass, bronze, copper, or other material may be employed on flange <b>177</b> under the land. First rocker member <b>173</b> may be made of a different material from the material from which the body of bearing adapter <b>156</b> is made more generally. That is to say, rocker member <b>173</b> may be made of a hard, or hardened material, such as a tool steel or a steel such as might be used in a bearing, that may be finished to a generally higher level of precision, and to a finer degree of surface roughness than the body of bearing adapter <b>156</b> more generally. Such a material may be suitable for rolling contact operation under high contact pressures.

Second rocker member <b>174</b> may be a disc of circular shape (in plan view) or other suitable shape having an upper surface for seating in pedestal seat <b>168,</b> or, in the event a pedestal seat member is not used, then formed directly to mate with the pedestal roof having an integrally formed seat. First rocker member <b>173</b> may have an upper, or rocker surface <b>175,</b> having a profile such as may give bi-directional lateral and longitudinal rocking motion when used in conjunction with the mating second, or upper rocker member, <b>174.</b> Second rocker member <b>174</b> may be made of a different material from the material from which the body of bearing adapter <b>171,</b> or the pedestal seat, is made more generally. Second rocker member <b>174</b> may be made of a hard, or hardened material, such as a tool steel or a steel such as might be used in a bearing, that may be finished to a generally higher level of precision, and to a finer degree of surface roughness than the body of sideframe <b>151</b> more generally. Such a material may be suitable for rolling contact operation under high contact pressures, particularly as when operated in conjunction with first rocker member <b>173.</b> Where an insert of dissimilar material is used, that material may tend to be rather more costly than the cast iron or relatively mild steel from which bearing adapters may otherwise tend to be made. Further still, an insert of this nature may be removed and replaced when worn, either on the basis of a scheduled rotation, or as the need may arise.

Resilient member <b>172</b> may be made of a composite or polymeric material, such as a polyurethane. Resilient member <b>172</b> may also have apertures, or reliefs <b>179</b> such as may be placed in a position for co-operation with corresponding drain holes <b>178.</b> The wall height of resilient member <b>172</b> may be sufficiently tall to engage the periphery of first rocker member <b>173.</b> Further, a portion of the radially outwardly facing peripheral edge of the second, upper, rocking member <b>174,</b> may also lie within, or may be partially overlapped by, and may possibly slightly stretchingly engage, the upper margin of resilient member <b>172</b> in a close, or interference, fit manner, such that a seal may tend to be formed to exclude dirt or moisture. In this way the assembly may tend to form a closed unit. In that regard, such space as may be formed between the first and second rockers <b>173,174</b> inside the dirt exclusion member may be packed with a lubricant, such as a lithium or other suitable grease.

Figures <b>4a - 4e</b>

As shown in <figref idref="f0008">Figures <b>4a - 4e</b></figref><b>,</b> resilient members <b>156</b> may have the general shape of a channel, having a central, or back, or transverse, or web portion <b>181,</b> and a pair of left and right hand, flanking wing portions <b>182, 183.</b> Wing portions <b>182</b> and <b>183</b> may tend to have downwardly and outwardly tending extremities that may tend to have an arcuate lower edge such as may seat over the bearing casing. The inside width of wing portions <b>182</b> and <b>183</b> may be such as to seat snugly about the sides of thrust blocks <b>180.</b> A transversely extending lobate portion <b>185,</b> running along the upper margin of web portion <b>181,</b> may seat in a radiused rebate <b>184</b> between the upper margin of thrust blocks <b>180</b> and the end of pedestal seat <b>168.</b> The inner lateral edge <b>186</b> of lobate portion <b>185</b> may tend to be chamfered, or relieved, to accommodate, and to seat next to, the end of pedestal seat <b>168.</b>

It may be desirable for the rocking assembly at the wheelset to sideframe interface to tend to maintain itself in a centered condition. As noted, the torsionally de-coupled bi-directional rocker arrangements disclosed herein may tend to have rocking stiffnesses that are proportional to the weight placed upon the rocker. Where a longitudinal rocking surface is used to permit self-steering, and the truck is experiencing reduced wheel load, (such as may approach wheel lift), or where the car is operating in the light car condition, it may be helpful to employ an auxiliary restorative centering element that may include a biasing element tending to urge the bearing adapter to a longitudinally centered position relative to the pedestal roof, and whose restorative tendency may be independent of the gravitational force experienced at the wheel. That is, when the bearing adapter is under less than full load, or is unloaded, it may be desirable to maintain a bias to a central position. Resilient members <b>156</b> described above may operate to urge such centering.

<figref idref="f0007">Figures <b>3c</b> and <b>3d</b></figref> illustrate the spatial relationship of the sandwich formed by (a) the bearing adapter, for example, bearing adapter <b>154;</b> (b) the centering member, such as, for example, resilient members 156; and (c) the pedestal jaw thrust blocks, <b>180.</b> Ancillary details such as, for example, drain holes or phantom lines to show hidden features have been omitted from <figref idref="f0007">Figures <b>3c</b> and <b>3d</b></figref> for clarity. When resilient member <b>156</b> is in place, bearing adapter <b>154</b> (or <b>171,</b> as may be); may tend to be centered relative to jaws <b>180.</b> As installed, the snubber (member <b>156)</b> may seat closely about the pedestal jaw thrust lug, and may seat next to the bearing adapter end wall and between the bearing adapter corner abutments in a slight interference fit. The snubber may be sandwiched between, and may establish the spaced relative position of, the thrust lug and the bearing adapter and may provide an initial central positioning of the mating rocker elements as well as providing a restorative bias. Although bearing adapter <b>154</b> may still rock relative to the sideframe, such rocking may tend to deform (typically, locally to compress) a portion of member <b>156,</b> and, being elastic, member <b>156</b> may tend to urge bearing adapter <b>154</b> toward a central position, whether there is much weight on the rocking elements or not. Resilient member <b>156</b> may have a restorative force-deflection characteristic in the longitudinal direction that is substantially less stiff than the force deflection characteristic of the fully loaded longitudinal rocker (perhaps one to two orders of magnitude less), such that, in a fully loaded car condition, member <b>156</b> may tend not significantly to alter the rocking behaviour. In one embodiment member <b>156</b> may be made of a polyurethane having a Young's modulus of some 6,500 p.s.i. In another embodiment the Young's modulus may be about 13,000 p.s.i. The Young's modulus of the elastomeric material may be in the range of 4 to 20 k.p.s.i. The placement of resilient members <b>156</b> may tend to center the rocking elements during installation. In one embodiment, the force to deflect one of the snubbers may be less than 20 % of the force to deflect the rocker a corresponding amount under the light car (i.e., unloaded) condition, and may, for small deflections, have an equivalent force/deflection curve slope that may be less than 10 % of the force deflection characteristic of the longitudinal rocker.

Figure <b>5</b>

Thus far only primary wedge angles have been discussed. <figref idref="f0008">Figure <b>5</b></figref> shows an isometric view of an end portion of a truck bolster <b>210.</b> As with all of the truck bolsters shown and discussed herein, bolster <b>210</b> is symmetrical about the central longitudinal vertical plane of the bolster (i.e., cross-wise relative to the truck generally) and symmetrical about the vertical mid-span section of the bolster (i.e., the longitudinal plane of symmetry of the truck generally, coinciding with the railcar longitudinal center line). Bolster <b>210</b> has a pair of spaced apart bolster pockets <b>212, 214</b> for receiving damper wedges <b>216, 218.</b> Pocket <b>212</b> is laterally inboard of pocket <b>214</b> relative to the side frame of the truck more generally. Wear plate inserts <b>220, 222</b> are mounted in pockets <b>212, 214</b> along the angled wedge face.

As can be seen, wedges <b>216, 218</b> have a primary angle, <b>α</b> as measured between vertical and the angled trailing vertex <b>228</b> of outboard face <b>230.</b> For the embodiments discussed herein, primary angle α may tend to lie in the range of 35 - 55 degrees, possibly about 40 - 50 degrees. This same angle <b>α</b> is matched by the facing surface of the bolster pocket, be it <b>212</b> or <b>214.</b> A secondary angle <b>β</b> gives the inboard, (or outboard), rake of the sloped surface <b>224,</b> (or <b>226)</b> of wedge <b>216</b> (or <b>218).</b> The true rake angle can be seen by sighting along plane of the sloped face and measuring the angle between the sloped face and the planar outboard face <b>230.</b> The rake angle is the complement of the angle so measured. The rake angle may tend to be greater than 5 degrees, may lie in the range of 5 to 20 degrees, and is preferably about 10 to 15 degrees. A modest rake angle may be desirable.

When the truck suspension works in response to track perturbations, the damper wedges may tend to work in their pockets. The rake angles yield a component of force tending to bias the outboard face <b>230</b> of outboard wedge <b>218</b> outboard against the opposing outboard face of bolster pocket <b>214.</b> Similarly, the inboard face of wedge <b>216</b> may tend to be biased toward the inboard planar face of inboard bolster pocket <b>212.</b> These inboard and outboard faces of the bolster pockets may be lined with a low friction surface pad, indicated generally as <b>232.</b> The left hand and right hand biases of the wedges may tend to keep them apart to yield the full moment arm distance intended, and, by keeping them against the planar facing walls, may tend to discourage twisting of the dampers in the respective pockets.

Bolster <b>210</b> includes a middle land <b>234</b> between pockets <b>212, 214,</b> against which another spring <b>236</b> may work. Middle land <b>234</b> is such as might be found in a spring group that is three (or more) coils wide. However, whether two, three, or more coils wide, and whether employing a central land or no central land, bolster pockets can have both primary and secondary angles as illustrated in the example embodiment of <figref idref="f0008">Figure <b>5a</b></figref>, with or without wear inserts.

Where a central land, e.g., land <b>234,</b> separates two damper pockets, the opposing side frame column wear plates need not be monolithic. That is, two wear plate regions could be provided, one opposite each of the inboard and outboard dampers, presenting planar surfaces against which the dampers can bear. The normal vectors of those regions may be parallel, the surfaces may be co-planar and perpendicular to the long axis of the side frame, and may present a clear, un-interrupted surface to the friction faces of the dampers.

Figure <b>1e</b>

<figref idref="f0002">Figure <b>1e</b></figref> shows an example of a three piece railroad car truck, shown generally as <b>250.</b> Truck <b>250</b> has a truck bolster <b>252,</b> and a pair of sideframes <b>254.</b> The spring groups of truck <b>250</b> are indicated as <b>256.</b> Spring groups <b>256</b> are spring groups having three springs <b>258</b> (inboard corner), <b>260</b> (center) and <b>262</b> (outboard corner) most closely adj acent to the sideframe columns <b>254.</b> A motion calming, kinematic energy dissipating element, in the nature of a friction damper <b>264, 266</b> is mounted over each of central springs <b>260.</b>

Friction damper <b>264, 266</b> has a substantially planar friction face <b>268</b> mounted in facing, planar opposition to, and for engagement with, a side frame wear member in the nature of a wear plate <b>270</b> mounted to sideframe column <b>254.</b> The base of damper <b>264, 266</b> defines a spring seat, or socket <b>272</b> into which the upper end of central spring <b>260</b> seats. Damper <b>264,266</b> has a third face, being an inclined slope or hypotenuse face <b>274</b> for mating engagement with a sloped face <b>276</b> inside sloped bolster pocket <b>278.</b> Compression of spring <b>260</b> under an end of the truck bolster may tend to load damper <b>264</b> or <b>266,</b> as may be, such that friction face <b>268</b> is biased against the opposing bearing face of the sideframe column, <b>280.</b> Truck <b>250</b> also has wheelsets whose bearings are mounted in the pedestal <b>284</b> at either ends of the side frames <b>254.</b> Each of these pedestals may accommodate one or another of the sideframe to bearing adapter interface assemblies described above and may thereby have a measure of self steering.

In this embodiment, vertcal face <b>268</b> of friction damper <b>264, 266</b> may have a bearing surface having a co-efficient of static friction, :_s, and a co-efficient of dynamic or kinetic friction, :k, that may tend to exhibit little or no "stick-slip" behaviour when operating against the wear surface of wear plate <b>270.</b> In one embodiment, the coefficients of friction are within 10 % of each other. In another embodiment the coefficients of friction are substantially equal and may be substantially free of stick-slip behaviour. In one embodiment, when dry, the coefficients of friction may be in the range of 0.10 to 0.45, may be in the narrower range of 0.15 to 0.35, and may be about 0.30. Friction damper <b>264, 266</b> may have a friction face coating, or bonded pad <b>286</b> having these friction properties, and corresponding to those inserts or pads described in the context of <figref idref="f0009">Figures <b>6a- 6c</b></figref>, and <figref idref="f0010 f0011 f0012 f0013 f0014 f0015 f0016 f0017 f0018 f0019 f0020 f0021 f0022 f0023 f0024 f0025 f0026 f0027 f0028 f0029 f0030 f0031 f0032 f0033 f0034">Figures <b>7a - 7h</b></figref>. Bonded pad <b>286</b> may be a polymeric pad or coating. A low friction, or controlled friction pad or coating <b>288</b> may also be employed on the sloped surface of the damper. In one embodiment that coating or pad <b>288</b> may have coefficients of static and dynamic friction that are within 20 %, or, more narrowly, 10% of each other. In another embodiment, the coefficients of static and dynamic friction are substantially equal. The co-efficient of dynamic friction may be in the range of 0.10 to 0.30, and may be about 0.20.

Figures <b>6a</b> to <b>6c</b>

The bodies of the damper wedges themselves may be made from a relatively common material, such as a mild steel or cast iron. The wedges may then be given wear face members in the nature of shoes, wear inserts or other wear members, which may be intended to be consumable items. In <figref idref="f0009">Figure <b>6a</b></figref>, a damper wedge is shown generically as <b>300.</b> The replaceable, friction modification consumable wear members are indicated as <b>302, 304.</b> The wedges and wear members may have mating male and female mechanical interlink features, such as the cross-shaped relief <b>303</b> formed in the primary angled and vertical faces of wedge <b>300</b> for mating with the corresponding raised cross shaped features <b>305</b> of wear members <b>302, 304.</b> Sliding wear member <b>302</b> may be made of a material having specified friction properties, and may be obtained from a supplier of such materials as, for example, brake and clutch linings and the like, such as Railway Friction Products. The materials may include materials that are referred to as being non-metallic, low friction materials, and may include UHMW polymers.

Although <figref idref="f0009">Figures <b>6a</b> and <b>6c</b></figref> show consumable inserts in the nature of wear plates, namely wear members <b>302, 304</b> the entire bolster pocket may be made as a replaceable part. It may be a high precision casting, or may include a sintered powder metal assembly having suitable physical properties. The part so formed may then be welded into place in the end of the bolster.

The underside of the wedges described herein, wedge <b>300</b> being typical in this regard, may have a seat, or socket <b>307,</b> for engaging the top end of the spring coil, whichever spring it may be, spring <b>262</b> being shown as typically representative. Socket <b>307</b> serves to discourage the top end of the spring from wandering away from the intended generally central position under the wedge. A bottom seat, or boss, for discouraging lateral wandering of the bottom end of the spring is shown in <figref idref="f0002">Figure <b>1e</b></figref> as item <b>308.</b> It may be noted that wedge <b>300</b> has a primary angle, but does not have a secondary rake angle. In that regard, wedge <b>300</b> may be used as damper <b>264, 266</b> of truck <b>250</b> of <figref idref="f0002">Figure <b>1e</b></figref>, for example, and may provide friction damping with little or no "stick-slip" behaviour, but rather friction damping for which the coefficients of static and dynamic friction are equal, or only differ by a small (less than about 20%, perhaps less than 10%) difference. Wedge <b>300</b> may be used in truck <b>250</b> in conjunction with a bi-directional bearing adapter of any of the embodiments described herein. Wedge <b>300</b> may also be used in a four cornered damper arrangement, as in truck <b>22,</b> for example, where wedges may be employed that may lack secondary angles.

Figures <b>7a - 7h</b>

Referring to <figref idref="f0010 f0011 f0012 f0013 f0014 f0015 f0016 f0017 f0018 f0019 f0020 f0021 f0022 f0023 f0024 f0025 f0026 f0027 f0028 f0029 f0030 f0031 f0032 f0033 f0034">Figures <b>7a - 7e</b></figref>, a damper <b>310</b> is shown such as may be used in truck <b>22,</b> or any of the other double damper trucks described herein, such as may have appropriately formed, mating bolster pockets. Damper <b>310</b> is similar to damper <b>300,</b> but may include both primary and secondary angles. Damper <b>310</b> may, arbitrarily, be termed a right handed damper wedge. <figref idref="f0010 f0011 f0012 f0013 f0014 f0015 f0016 f0017 f0018 f0019 f0020 f0021 f0022 f0023 f0024 f0025 f0026 f0027 f0028 f0029 f0030 f0031 f0032 f0033 f0034">Figures <b>7a - 7e</b></figref> are intended to be generic such that it may be understood also to represent the left handed, mirror image of a mating damper with which damper <b>310</b> would form a matched pair.

Wedge <b>310</b> has a body <b>312</b> that may be made by casting or by another suitable process. Body <b>312</b> may be made of steel or cast iron, and may be substantially hollow. Body <b>312</b> has a first, substantially planar platen portion <b>314</b> having a first face for placement in a generally vertical orientation in opposition to a sideframe bearing surface, for example, a wear plate mounted on a sideframe column. Platen portion <b>314</b> may have a rebate, or relief, or depression formed therein to receive a bearing surface wear member, indicated as member <b>316.</b> Member <b>316</b> may be a material having specific friction properties when used in conjunction with the sideframe column wear plate material. For example, member <b>316</b> may be formed of a brake lining material, and the column wear plate may be formed from a high hardness steel.

Body <b>312</b> may include a base portion <b>318</b> that may extend rearwardly from and generally perpendicularly to, platen portion <b>314.</b> Base portion <b>318</b> may have a relief <b>320</b> formed therein in a manner to form, roughly, the negative impression of an end of a spring coil, such as may receive a top end of a coil of a spring of a spring group, such as spring <b>262.</b> Base portion <b>318</b> may join platen portion <b>314</b> at an intermediate height, such that a lower portion <b>321</b> of platen portion <b>314</b> may depend downwardly therebeyond in the manner of a skirt. That skirt portion may include a corner, or wrap around portion <b>322</b> formed to seat around a portion of the spring.

Body <b>312</b> may also include a diagonal member in the nature of a sloped member <b>324.</b> Sloped member <b>324</b> may have a first, or lower end extending from the distal end of base <b>318</b> and running upwardly and forwardly toward a junction with platen portion <b>314.</b> An upper region <b>326</b> of platen portion <b>314</b> may extend upwardly beyond that point of junction, such that damper wedge <b>310</b> may have a footprint having a vertical extent somewhat greater than the vertical extent of sloped member <b>324.</b> Sloped member <b>324</b> may also have a socket or seat in the nature of a relief or rebate <b>328</b> formed therein for receiving a sliding face member <b>330</b> for engagement with the bolster pocket wear plate of the bolster pocket into which wedge <b>310</b> may seat. As may be seen, sloped member <b>324</b> (and face member <b>330)</b> are inclined at a primary angle α, and a secondary angle <b>β.</b> Sliding face member <b>330</b> may be an element of chosen, possibly relatively low, friction properties (when engaged with the bolster pocket wear plate), such as may include desired values of coefficients of static and dynamic friction. In one embodiment the coefficients of static and dynamic friction may be substantially equal, may be about 0.2 (+/- 20 %, or, more narrowly +/- 10%), and may be substantially free of stick-slip behaviour.

In the alternative embodiment of <figref idref="f0009">Figure <b>7g</b></figref><b>,</b> a damper wedge <b>332</b> is similar to damper wedge <b>310,</b> but, in addition to pads or inserts for providing modified or controlled friction properties on the friction face for engaging the sideframe column and on the face for engaging the slope of the bolster pocket, damper wedge <b>332</b> may have pads or inserts such as pad <b>334</b> on the side faces of the wedge for engaging the side faces of the bolster pockets. In this regard, it may be desirable for pad <b>334</b> to have low coefficients of friction, and to tend to be free of stick slip behaviour. The friction materials may be cast or bonded in place, and may include mechanical interlocking features, such as shown in <figref idref="f0009">Figure <b>6a</b></figref>, or bosses, grooves, splines, or the like such as may be used for the same purpose. Similarly, in the alternative embodiment of <figref idref="f0009">Figure <b>7h</b></figref>, a damper wedge <b>336</b> is provided in which the slope face insert or pad, and the side wall insert or pad form a continuous, or monolithic, element, indicated as <b>338.</b> The material of the pad or insert may, again, be cast in place, and may include mechanical interlock features.

Figures <b>8a-8f</b>

<figref idref="f0011 f0012">Figures <b>8a - 8f</b></figref> show an alternate bearing adapter assembly to that of <figref idref="f0006">Figure <b>3a</b></figref>. The assembly, indicated generally as <b>350,</b> may differ from that of <figref idref="f0006">Figure <b>3a</b></figref> insofar as bearing adapter <b>344</b> may have an upper surface <b>346</b> that may be a load bearing interface surface of significant extent, that may be substantially planar and horizontal, such that it may act as a base upon which to seat a rocker element, <b>348.</b> Rocker element <b>348</b> may have an upper, or rocker, surface <b>352</b> having a suitable profile, such as a compound curvatures having lateral and longitudinal radii of curvature, for mating with a corresponding rocker engagement surface of a pedestal seat liner <b>354.</b> As noted above, in the general case each of the two rocking engagement surface may have both lateral and longitudinal radii of curvature, such that there are mating lateral male and female radii, and mating longitudinal male and female radii. In one embodiment, both the female radii may be infinite, such that the pedestal seat may have a planar engagement surface, and the pedestal seat liner may be a wear liner, or similar device.

Rocker element <b>348</b> may also have a lower surface <b>356</b> for seating on, mating with, and for transferring loads into, upper surface <b>346</b> over a relatively large surface area, and may have a suitable through thickness for diffusing vertical loading from the zone of rolling contact to the larger area of the land (i.e., surface <b>346,</b> or a portion thereof) upon which rocker element <b>348</b> sits. Lower surface <b>356</b> may also include a keying, or indexing feature <b>358</b> of suitable shape, and may include a centering feature <b>360,</b> both to aid in installation, and to aid in re-centering rocker element <b>348</b> in the event that it should be tempted to migrate away from the central position during operation. Indexing feature <b>358</b> may also include an orienting element for discouraging misorientation of rocker element <b>348.</b> Indexing feature <b>358</b> may be a cavity <b>362</b> of suitable shape to mate with an opposed button <b>364</b> formed on the upper surface <b>346</b> of bearing adapter <b>344.</b> If this shape is non-circular, it may tend to admit of only one permissible orientation. The orienting element may be defined in the plan form shape of cavity <b>362</b> and button <b>364.</b> Where the various radii of curvature of rocker element <b>348</b> differ in the lateral and longitudinal directions, it may be that two positions 180 degrees out of phase may be acceptable, whereas another orientation may not. While an ellipse of differing major and minor axes may serve this purpose, the shape of cavity <b>362</b> and button <b>364</b> may be chosen from a large number of possibilities, and may have a cruciform or triangular shape, or may include more than one raised feature in an asymmetrical pattern, for example. The centering feature may be defined in the tapered, or sloped, flanks <b>368</b> and <b>370</b> of cavity <b>362</b> and <b>364</b> respectively, in that, once positioned such that flanks <b>368</b> and <b>370</b> begin to work against each other, a normal force acting downward on the interface may tend to cause the parts to center themselves.

Rocker element <b>348</b> has an external periphery <b>372,</b> defining a footprint. Resilient members <b>374</b> may be taken as being the same as resilient members <b>156,</b> noted above, except insofar as resilient members <b>374</b> may have a depending end portion for nesting about the thrust block of a jaw of the pedestal, and also a predominantly horizontally extending portion <b>376</b> for overlying a substantial portion of the generally flat or horizontal upper region of bearing adapter <b>344.</b> That is, the outlying regions of surface <b>346</b> of bearing adapter <b>344</b> may tend to be generally flat, and may tend, due to the general thickness of rocker element <b>348,</b> to be compelled to stand in a spaced apart relationship from the opposed, downwardly facing surface of the pedestal seat, such as may be, for example, the exposed surface of a wear liner such as item <b>354,</b> or a seat such as item <b>168,</b> or such other mating part as may be suitable. Portion <b>376</b> is of a thickness suitable for lying in the gaps so defined, and may tend to be thinner than the mean gap height so as not to interfere with operation of the rocker elements. Horizontally extending portion <b>376</b> may have the form of a skirt such as may include a pair of left and right hand arms or wings <b>378</b> and <b>380</b> having a profile, when seen in plan view, for embracing a portion of periphery <b>372.</b> Resilient member <b>374</b> has a relief <b>382</b> defined in the inwardly facing edge. Where rocker member <b>348</b> has outwardly extending blisters, or cusps, akin to item <b>164,</b> relief <b>382</b> may function as an indexing or orientation feature. A relatively coarse engagement of rocker element <b>348</b> may tend to result in wings <b>378</b> and <b>380</b> urging rocker element <b>348</b> to a generally centered position relative to bearing adapter <b>344.</b> This coarse centering may tend to cause cavity <b>362</b> to pick up on button <b>364,</b> such that rocker member <b>348</b> is then urged to the desired centered position by a fine centering feature, namely the chamfered flanks <b>368, 370.</b> The root of portion <b>376</b> may be relieved by a radius <b>384</b> adjacent the juncture of surface <b>346</b> with the end wall <b>386</b> of bearing adapter <b>348</b> to discourage chaffing of resilient member <b>372, 374</b> at that location.

Without the addition of a multiplicity of drawings, it may be noted that rocker element <b>348</b> could, alternatively, be inverted so as to, seat in an accommodation formed in the pedestal roof, with a land facing toward the roof, and a rocking surface facing toward a mating bearing adapter, be it adapter <b>44</b> or some other.

Figures <b>9a</b> and <b>9b</b>

<figref idref="f0013">Figure <b>9a</b></figref> shows an alternative arrangement to that of <figref idref="f0006">Figure <b>3a</b></figref> or <figref idref="f0011">Figure <b>8a</b></figref><b>.</b> In the wheelset to sideframe interface assembly of <figref idref="f0013">Figure <b>9a</b></figref><b>,</b> indicated generally as <b>400,</b> bearing adapter <b>404</b> may be substantially similar to bearing adapter <b>344,</b> and may have an upper surface <b>406</b> and a rocker element <b>408</b> that interact in the same manner as rocker element <b>348</b> interacts with surface <b>346.</b> (Or, in the inverted case, the rocker element may be seated in the pedestal roof, and the bearing adapter may have a mating upwardly facing rocker surface). The rocker element may interact with a pedestal seat fitting <b>410</b> such as may be a wear liner seated in the pedestal roof. Rocker element <b>408</b> and the body of bearing adapter <b>404</b> may have mating indexing features as described in the context of <figref idref="f0011 f0012">Figures <b>8a</b> to <b>8e</b></figref><b>.</b>

Rather than two resilient members, such as items <b>374,</b> however, assembly <b>400</b> employs a single resilient member <b>412,</b> such as may be a monolithic cast material, be it polyurethane or a suitable rubber or rubberlike material such as may be used, for example, in making an LC pad or a Pennsy pad. An LC pad is an elastomeric bearing adapter pad available from Lord Corporation of Erie Pennsylvania. An example of an LC pad may be identified as Standard Car Truck Part Number SCT 5578. In this instance, resilient member <b>412</b> has first and second end portions <b>414, 416</b> for interposition between the thrust lugs of the jaws of the pedestal and the ends <b>418</b> and <b>420</b> of the bearing adapter. End portions <b>414, 416</b> may tend to be a bit undersize so that, once the roof liner is in place, they may slide vertically into place on the thrust lugs, possibly in a modest interference fit. The bearing adapter may slide into place thereafter, and again, may do so in a slight interference fit, carrying the rocker element <b>408</b> with it into place.

Resilient member <b>412</b> may also have a central or medial portion <b>422</b> extending between end portions <b>414, 416.</b> Medial portion <b>422</b> may extend generally horizontally inward to overlie substantial portions of the upper surface bearing adapter <b>404.</b> Resilient member <b>412</b> may have an accommodation <b>424</b> formed therein, be it in the nature of an aperture, or through hole, having a periphery of suitable extent to admit rocker element <b>408,</b> and so to permit rocker element <b>408</b> to extend at least partially through member <b>412</b> to engage the mating rocking element of the pedestal seat. It may be that the periphery of accommodation <b>422</b> is matched to the shape of the footprint of rocker element <b>408</b> in the manner described in the context of <figref idref="f0011 f0012">Figures <b>8a</b> to <b>8e</b></figref> to facilitate installation and to facilitate location of rocker element <b>408</b> on bearing adapter <b>404.</b> In one embodiment resilient member <b>412</b> may be formed in the manner of a Pennsy Pad with a suitable central aperture formed therein.

<figref idref="f0013">Figure <b>9b</b></figref> shows a Pennsy pad installation. In this installation, a bearing adapter is indicated as <b>430,</b> and an elastomeric member, such as may be a Pennsy pad, is indicated as <b>432.</b> On installation, member <b>432</b> seats between the pedestal roof and the bearing adapter. The term "Pennsy pad", or "Pennsy Adapter Plus", refers to a kind of elastomeric pad developed by Pennsy Corporation of Westchester Pa. One example of such a pad is illustrated in <patcit id="pcit0004" dnum="US5562045A"><text>US Patent 5,562,045 of Rudibaugh et al., issued October 6, 1996</text></patcit> (and which is incorporated herein by reference). <figref idref="f0013">Figure <b>9b</b></figref> may include a pad <b>432</b> and bearing adapter of <b>430</b> the same, or similar, nature to those shown and described in the 5,562,045 patent. The Pennsy pad may tend to permit a measure of passive steering. The Pennsy pad installation of <figref idref="f0013">Figure <b>9b</b></figref> can be installed in the sideframe of <figref idref="f0001">Figure <b>1a</b></figref><b>,</b> in combination with a four cornered damper arrangement, as indicated in <figref idref="f0001 f0002">Figures <b>1a -1d</b></figref><b>.</b> In this embodiment the truck may be a Barber S2HD truck, modified to carry a damper arrangement, such as a four-cornered damper arrangement, such as may have an enhanced restorative tendency in the face of non-square deformation of the truck, having dampers that may include friction surfaces as described herein.

Figures <b>10a - 10e</b>

<figref idref="f0014">Figure <b>10a</b></figref> shows a further alternate embodiment of wheelset to sideframe interface assembly to that of <figref idref="f0006">Figure <b>3a</b></figref> or <figref idref="f0011">Figure <b>8a</b></figref><b>.</b> In this instance, bearing adapter <b>444</b> may have an upper rocker surface of any of the configurations discussed above, or may have a rocker element in the manner of bearing adapter <b>344.</b>

The underside of bearing adapter <b>444</b> may have not only a circumferentially extending medial groove, channel or rebate <b>446,</b> having an apex lying on the transverse plane of symmetry of bearing adapter <b>444,</b> but also a laterally extending underside rebate <b>448</b> such as may tend to lie parallel to the underlying longitudinal axis of the wheelset shaft and bearing centreline (i.e., the axial direction) such that the underside of bearing adapter <b>444</b> has four corner lands or pads <b>450</b> arranged in an array for seating on the casing of the bearing. In this instance, each of the pads, or lands, may be formed on a curved surface having a radius conforming to a body of revolution such as the outer shell of the bearing. Rebate <b>448</b> may tend to lie along the apex of the arch of the underside of bearing adapter <b>444,</b> with the intersection of rebates <b>446</b> and <b>448.</b> Rebate <b>448</b> may be relatively shallow, and may be gently radiused into the surrounding bearing adapter body. The body of bearing adapter <b>444</b> is more or less symmetrical about both its longitudinal central vertical plane (i.e., on installation, that plane lying vertical and parallel to, if not coincident with, the longitudinal vertical central plane of the sideframe), and also about its transverse central plane (i.e., on installation, that plane extending vertically radially from the center line of the axis of rotation of the bearing and of the wheelset shaft). It may be noted that axial rebate <b>448</b> may tend to lie at the section of minimum cross-sectional area of bearing adapter <b>444.</b> In the view of the present inventors, rebates <b>446</b> and <b>448</b> may tend to divide, and spread, the vertical load carried through the rocker element over a larger area of the casing of the bearing, and hence to more evenly distribute the load into the elements of the bearing than might otherwise be the case. It is thought that this may tend to encourage longer bearing life.

In the general case, bearing adapter <b>444</b> may have an upper surface having a crown to permit self-steering, or may be formed to accommodate a self-steering apparatus such as an elastomeric pad, such as a Pennsy Pad or other pad. In the event that a rocker surface is employed, whether by way of a separable insert, or a disc, or is integrally formed in the body of the bearing adapter, the location of the contact of the rocker in the resting position may tend to lie directly above the center of the bearing adapter, and hence above the intersection of the axial and circumferential rebates in the underside of bearing adapter <b>444.</b>

Figures <b>11a - 11f</b>

<figref idref="f0015 f0016 f0017 f0018 f0019 f0020 f0021 f0022 f0023 f0024 f0025 f0026 f0027 f0028 f0029 f0030 f0031 f0032 f0033 f0034">Figures <b>11a - 11f</b></figref> show views of a bearing adapter <b>452,</b> a pedestal seat insert <b>454</b> and elastomeric bumper pad members <b>456,</b> as an assembly for insertion between bearing <b>46</b> and sideframe <b>26.</b> Bearing adapter <b>452</b> and pad members <b>456</b> are generally similar to bearing adapter <b>171</b> and members <b>156,</b> respectively. They differ, however, insofar as bearing adapter <b>452</b> has thrust block standoff elements <b>460, 462</b> located at either end thereof, and the lower corners of bumpers <b>456</b> have been truncated accordingly. It may be that for a certain range of deflection, an elastomeric response is desired, and may be sufficient to accommodate a high percentage of in-service performance. However, excursion beyond that range of deflection might tend to cause damage, or reduction in life, to pad members <b>456.</b> Standoff elements <b>460, 462</b> may act as limiting stops to bound that range of motion. Standoff elements <b>460, 462</b> may have the form of shelves, or abutments, or stops <b>466, 468</b> mounted to, and standing proud of, the laterally inwardly facing faces of the corner abutment portions <b>470, 472</b> of bearing adapter <b>452</b> more generally. As installed, stops <b>466, 468</b> underlie toes <b>474, 476</b> of members <b>456.</b> As may be noted, toes <b>474, 476</b> have a truncated appearance as compared to the toes of member <b>356</b> in order to stand clear of stops <b>466, 468</b> on installation. In the at rest, centered condition, stops <b>466, 468</b> may tend to stand clear of the pedestal jaw thrust blocks by some gap distance. When the lateral deflection of the elastomer in member <b>456</b> reaches the gap distance, the thrust lug may tend to bottom against stop <b>466</b> or <b>468,</b> as the case may be. The sheltering width of stops <b>466, 468</b> (i.e., the distance by which they stand proud of the inner face of corner abutment portions <b>470, 472)</b> may tend to provide a reserve compression zone for wings <b>475, 477</b> and may thereby tend to prevent them from being unduly squeezed or pinched. Pedestal seat insert <b>454</b> may be generally similar to liner <b>354,</b> but may include radiused bulges <b>480, 482,</b> and a thicker central portion <b>484.</b> Bearing adapter <b>452</b> may include a central bi-directional rocker portion <b>486</b> for mating rocking engagement with the downwardly facing rocking surface of central portion <b>484.</b> The mating surfaces may conform to any of the combinations of bi-directional rocking radii discussed herein. Rocker portion <b>486</b> may be trimmed laterally as at longitudinally running side shoulders <b>488, 490</b> to accommodate bulges <b>480, 482.</b>

Bearing adapter <b>452</b> may also have different underside grooving, <b>492</b> in the nature of a pair of laterally extending tapered lobate depressions, cavities, or reliefs <b>494, 496</b> separated by a central bridge region <b>498</b> having a deeper section and flanks that taper into reliefs <b>494, 496.</b> Reliefs <b>494, 496</b> may have a major axis that runs laterally with respect to the bearing adapter itself, but, as installed, runs axially with respect to the axis of rotation of the underlying bearing. The absence of material at reliefs <b>494, 496</b> may tend to leave a generally H-shaped footprint on the circumferential surface <b>500</b> that seats upon the outside of bearing <b>46,</b> in which the two side regions, or legs, of the H form lands or pads <b>502, 504</b> joined by a relatively narrow waist, namely bridge region <b>498.</b> To the extent that the undersurface of the lower portion of bearing adapter <b>452</b> conforms to an arcuate profile, such as may accommodate the bearing casing, reliefs <b>494, 496</b> may tend to run, or extend, predominantly along the apex of the profile, between the pads, or lands, that lie to either side. This configuration may tend to spread the rocker rolling contact point load into pads <b>502, 504</b> and thence into bearing <b>46.</b> Bearing life may be a function of peak load in the rollers. By leaving a space between the underside of the bearing adapter and the top center of the bearing casing over the bearing races, reliefs <b>494, 496</b> may tend to prevent the vertical load being passed in a concentrated manner predominantly into the top rollers in the bearing. Instead, it may be advantageous to spread the load between several rollers in each race. This may tend to be encouraged by employing spaced apart pads or lands, such as pads <b>502, 504,</b> that seat upon the bearing casing. Central bridge region <b>498</b> may seat above a section of the bearing casing under which there is no race, rather than directly over one of the races. Bridge region <b>498</b> may act as a central circumferential ligature, or tension member, intermediate bearing adapter end arches <b>506, 508</b> such as may tend to discourage splaying or separation of pads <b>502, 504</b> away from each other as vertical load is applied.

Figures <b>12a-12d</b>

<figref idref="f0016">Figures <b>12a</b> to <b>12d</b></figref> show an alternate assembly to that of <figref idref="f0015">Figure 11a</figref>, indicated generally as <b>510</b> for seating in a sideframe <b>512.</b> Bearing <b>46</b> and bearing adapter <b>452</b> may be as before. Assembly <b>510</b> may include an upper rocker fitting identified as pedestal seat member <b>514,</b> and resilient members <b>516.</b> Sideframe <b>512</b> may be such that the upper rocker fitting, namely pedestal seat member <b>514</b> may have a greater through thickness, <b>t_s</b>, than otherwise. This thickness, <b>t_s</b> may be greater than 10 % of the magnitude of the width W_s of the pedestal seat member, and may be about 20 (+/-5) % of the width. In one embodiment the thickness may be roughly the same as the thickness of and 'LC pad' such as may be obtained from Lord Corporation. Such thickness may be greater than 7/16", and such thickness may be 1 inch (+/-1/8"). Pedestal seat member <b>514</b> may tend to have a greater thickness for enhancing the spreading of the rocker contact load into sideframe <b>512.</b> It may also be used as part of a retro-fit installation in sideframes such as may formerly have been made to accommodate LC pads.

Pedestal seat member <b>514</b> may have a generally planar body <b>518</b> having upturned lateral margins <b>520</b> for bracketing, and seating about, the lower edges of the sideframe pedestal roof member <b>522.</b> The major portion of the upper surface of body <b>518</b> may tend to mate in planar contact with the downwardly facing surface of roof member <b>522.</b> Seat member <b>514</b> may have protruding end potions <b>524</b> that extend longitudinally from the main, planar portion of body <b>518.</b> End portions <b>524</b> may include a deeper nose section <b>526,</b> that may stand downwardly proud of two wings <b>528, 530.</b> The depth of nose section <b>526</b> may correspond to the general through thickness depth of member <b>514.</b> The lower, downwardly facing surface <b>532</b> of member <b>518</b> (as installed) may be formed to mate with the upper surface of the bearing adapter, such that a bi-directional rocking interface is achieved, with a combination of male and female rocking radii as described herein. In one embodiment the female rocking surface may be planar.

Resilient members <b>516</b> may be formed to engage protruding portions <b>524.</b> That is, resilient member <b>516</b> may have the generally channel shaped for of resilient member <b>156,</b> having a lateral web <b>534</b> standing between a pair of wings <b>536, 538.</b> However, in this embodiment, web <b>534</b> may extend, when installed, to a level below the level of stops <b>466, 468,</b> and the respective base faces <b>540, 542</b> of wings <b>536, 538</b> are positioned to sit above stops <b>466, 468.</b> A superior lateral wall, or bulge, <b>544</b> surmounts the upper margin of web <b>534,</b> and extends longitudinally, such as may permit it to overhang the top of the sideframe jaw thrust lug <b>546.</b> The upper surface of bulge <b>544</b> may be trimmed, or flattened to accommodate nose section <b>526.</b> The upper extremities of wings <b>536, 538</b> terminate in knobs, or prongs, or horns <b>548, 550</b> that stand upwardly proud of the flattened surface <b>552</b> of bulge <b>544.</b> As installed, the upper ends of horns <b>548, 550</b> underlie the downwardly facing surfaces of wings <b>536, 538.</b>

In the event that an installer might attempt to install bearing adapter <b>452</b> in sideframe <b>512</b> without first placing pedestal seat member <b>512</b> in position, the height of horns <b>548, 550</b> is sufficient to prevent the rocker surface of bearing adapter <b>452</b> from engaging sideframe roof member <b>522.</b> That is, the height of the highest portion of the crown of the rocker surface <b>552</b> of the bearing adapter is less than the height of the ends of horns <b>548, 550</b> when horns <b>548, 550</b> are in contact with stops <b>466, 468.</b> However, when pedestal seat member <b>512</b> is correctly in place, nose section <b>526</b> is located between wings <b>536, 538,</b> and wings <b>536, 538</b> are captured above horns <b>548, 550.</b> In this way, resilient members <b>514,</b> and in particular horns <b>548, 550,</b> act as installation error detection elements, or damage prevention elements.

The steps of installation may include the step of removing an existing bearing adapter, removing an existing elastomeric pad, such as an LC pad, installing pedestal seat fitting <b>514</b> in engagement with roof <b>522;</b> seating of resilient members <b>514</b> above each of thrust lugs <b>546;</b> and sliding bearing adapter <b>452</b> between resilient pad members <b>514.</b> Resilient pad members <b>514</b> then serve to locate other elements on assembly, to retain those elements in service, and to provide a centering bias to the mating rocker elements, as discussed above.

Figures <b>13a - 13gs</b>

<figref idref="f0017 f0018">Figures <b>13a</b> to <b>13g</b></figref> show and alternate bearing adapter <b>144</b> and pedestal seat <b>146</b> pair. Bearing adapter <b>144</b> is substantially the same as bearing adapter <b>44,</b> except insofar as bearing adapter <b>44</b> has a fully curved top surface <b>142,</b> whereas bearing adapter <b>144</b> has an upper surface that has a flat central portion <b>148</b> between somewhat elevated side portions <b>149.</b> The male bearing surface portion <b>147</b> is located centrally on flat central portion <b>148,</b> and extends upwardly therefrom. As with bearing adapter <b>44,</b> bearing adapter <b>144</b> has first and second radii <b>r₁</b> and <b>r₂</b>, formed in the longitudinal and transverse directions respectively, such that the upwardly protruding surface so formed is a toroidal surface. Pedestal seat <b>146</b> is substantially similar to pedestal seat fitting <b>38.</b> Pedestal seat <b>146</b> has a body having an upper surface <b>145</b> that seats in planar abutment against the downwardly facing surface of pedestal roof <b>120,</b> and upwardly extending tangs <b>124</b> that engage lugs <b>122</b> as before. While in the general sense, the female engagement fitting portion, namely the hollow depression formed in the lower face of seat <b>146,</b> is formed on longitudinal and lateral radii <b>R₁</b> and <b>R₂,</b> as above, when these two radii are equal a spherical surface <b>143</b> is formed, giving the circular plan view of <figref idref="f0017">Figure 13a</figref>. <figref idref="f0018">Figures <b>13f</b> and <b>13g</b></figref> serve to illustrate that the male and female surfaces may be inverted, such that the female engagement surface <b>560</b> is formed on bearing adapter <b>562,</b> and the male engagement surface <b>564</b> on seat <b>566.</b>

Figures <b>14a -14e</b>

<figref idref="f0019">Figures <b>14a - 14e</b></figref> show enlarged views of bearing adapter <b>44</b> and pedestal seat fitting <b>38.</b> The compound curve of upwardly facing surface <b>142</b> runs fully to terminate at the end faces <b>134,</b> and the side faces <b>570</b> of bearing adapter <b>44.</b> The side faces show the circularly downwardly arched lower walls margins <b>572</b> of side faces <b>570</b> that seat about bearings <b>46.</b> In all other respects, for the purposes of this description, bearing adapter <b>44</b> can be taken as being the same as bearing adapter <b>144.</b>

Figures <b>15a -15c</b>

<figref idref="f0018">Figures <b>15a-15c</b></figref><b>,</b> show a conceptually similar bearing adapter and pedestal seat combination to that of <figref idref="f0017 f0018">Figures <b>13a</b> to <b>13g</b></figref><b>,</b> but rather than having the interface portions standing proud of the remainder of the bearing adapter, the male portion <b>574</b> is sunken into the top of the bearing adapter, and the surrounding surface <b>576</b> is raised up. The mating female portion <b>578</b> while retaining its hollowed out shape, stands proud of the surrounding structure of the seat to provide a corresponding mating surface. The longitudinally extending phantom lines indicate drain ports to discourage the collection of water.

Figures <b>16a 16e</b>

Both female radii <b>R₁</b> and <b>R₂</b> need not be on the same fitting, and both male radii r₁ and r₂ need not be on the same fitting. In the saddle shaped fittings of <figref idref="f0020">Figures <b>16a</b> to <b>16e</b></figref><b>,</b> a bearing adapter <b>580</b> is of substantially the same construction as bearing adapters <b>44</b> and <b>144,</b> except insofar as bearing adapter <b>580</b> has an upper surface <b>592</b> that has a male fitting in the nature of a longitudinally extending crown <b>582</b> with a laterally extending axis of rotation, for which the radius of curvature is <b>r₁,</b> and a female fitting in the nature of a longitudinally extending trough <b>584</b> having a lateral radius of curvature <b>R₂.</b> Similarly, pedestal fitting <b>586</b> mounted in roof <b>120</b> has a generally downwardly facing surface <b>594</b> that has a transversely extending trough <b>588</b> having a longitudinally oriented radius of curvature <b>R₁,</b> for engagement with <b>r₁</b> of crown <b>582,</b> and a longitudinally running, downwardly protruding crown <b>590</b> having a transverse radius of curvature r₂ for engagement with <b>R₂</b> of trough <b>584.</b> In <figref idref="f0021">Figures <b>16f</b> and <b>16g</b></figref> the saddle surfaces are inverted such that whereas bearing adapter <b>580</b> has <b>r₁</b> and <b>R₂,</b> bearing adapter <b>596</b> has <b>r₂</b> and <b>R₁.</b> Similarly, whereas pedestal fitting <b>586</b> has <b>r₂</b> and <b>R₁,</b> pedestal fitting <b>598</b> has <b>r₁</b> and <b>R₂.</b> In either case, the smallest of <b>R₁</b> and <b>R₂</b> may be larger than, or equal to, the largest of <b>r₁</b> and <b>r₂,</b> and the mating opposed saddle surfaces, over the desired range of motion, may tend to be torsionally decoupled as in bearing adapters <b>44</b> and <b>144.</b>

Figures <b>17a -17d</b>

It may be desired that the vertical forces transmitted from the pedestal roof into the bearing adapter be passed through line contact, rather than the bi-directional rolling or rocking point contact. A pedestal seat to bearing adapter interface assembly having line contact rocker interfaces is represented by <figref idref="f0022 f0023 f0024 f0025 f0026 f0027 f0028 f0029 f0030 f0031 f0032 f0033 f0034">Figures <b>17a</b> to <b>17d</b></figref>. A bearing adapter <b>600</b> has a hollowed out transverse cylindrical upper surface <b>602,</b> acting as a female engagement fitting portion formed on radius <b>R₁</b>. Surface <b>602</b> may be a round cylindrical section, or it may be parabolic, or other cylindrical section.

The corresponding pedestal seat fitting <b>604</b> may have a longitudinally extending female fitting, or trough, <b>606</b> having a cylindrical surface <b>608</b> formed on radius <b>r₁</b>. Again, fitting <b>604</b> is cylindrical, and may be a round cylindrical section although, alternatively, it could be parabolic, elliptic, or some other shape for producing a rocking motion. Trapped between bearing adapter <b>600</b> and pedestal seat fitting <b>604</b> is a rocker member <b>610.</b> Rocker member <b>610</b> has a first, or lower portion <b>612</b> having a protruding male cylindrical rocker surface <b>614</b> formed on a radius <b>r₁</b> for line contact engagement of surface <b>602</b> of bearing adapter <b>600</b> formed on radius <b>R₁, r₁</b> being smaller than <b>R₁,</b> and thus permitting longitudinal rocking to obtain passive self steering. As above, the resistance to rocking, and hence to self steering, may tend to be proportional to the weight on the rocker and hence may give proportional self steering when the car is either empty or loaded. Lower portion <b>612</b> also has an upper relief <b>616</b> that may be machined to a high level of flatness. Lower portion <b>612</b> also has a centrally located, integrally formed upwardly extending cylindrical stub <b>618</b> that stands perpendicularly proud of surface <b>616.</b> A bushing <b>620,</b> which may be a press fit bushing, mounts on stub <b>618.</b>

Rocker member <b>600</b> also has an upper portion <b>622</b> that has a second protruding male cylindrical rocker surface <b>624</b> formed on a radius <b>r₂</b> for line contact engagement with the cylindrical surface <b>608</b> of trough <b>606,</b> formed on radius <b>R₂,</b> thus permitting lateral rocking of sideframe <b>26.</b> Upper portion <b>622</b> may have a lower relief <b>626</b> for placement in opposition to relief <b>616.</b> Upper portion <b>622</b> has a centrally located blind bore <b>628</b> of a size for tight fitting engagement of bushing <b>620,</b> such that a close tolerance, pivoting connection is obtained that is largely compliant to pivotal motion about the vertical, or z, axis of upper portion <b>622</b> with respect to lower portion <b>612.</b> That is to say, the resistance to torsional motion about the z-axis is very small, and can be taken as zero for the purposes of analysis. To aid in this, bearing <b>630</b> may be installed about stub <b>618</b> and bushing <b>620</b> and is placed between opposed surfaces <b>606</b> and <b>616</b> to encourage relative rotational motion therebetween.

In this embodiment, stub <b>618</b> could be formed in upper portion <b>622,</b> and bore <b>618</b> formed in lower portion <b>612,</b> or, alternatively, bores <b>628</b> could be formed in both upper portion <b>612</b> and lower portion <b>622,</b> and a freely floating stub <b>618</b> and bushing <b>620</b> could be captured between them. It may be noted that the angular displacement about the z axis of upper portions <b>622</b> relative to lower portion <b>612</b> may be quite small - of the order of 1 degree, and may tend not to be even that large overly frequently.

Bearing adapter <b>600</b> may have longitudinally extending raised lateral abutment side walls <b>632</b> to discourage lateral migration, or escape of lower portion <b>612.</b> Lower portion <b>612</b> may have non-galling, relatively low co-efficient of friction side wear shim stock members <b>634</b> trapped between the end faces of lower portion <b>612</b> and side walls <b>632.</b> Bearing adapter <b>600</b> may also have a drain hole formed therein, possibly centrally, or placed at an angle. Similarly, pedestal seat fitting <b>604</b> may have laterally extending depending end abutment walls <b>636</b> to discourage longitudinal migration, or escape, of upper portion <b>622.</b> In a like manner to shim stock members <b>634,</b> non-galling, relatively low co-efficient of friction end wear shim stock members <b>638</b> may be mounted between the end faces of upper portion <b>622</b> and end abutment walls <b>636.</b>

In an alternative to the foregoing embodiment, the longitudinal cylindrical trough could be formed on the bearing adapter, and the lateral cylindrical trough could be formed in the pedestal seat, with corresponding changes in the entrapped rocker element. Further, it is not necessary that the male cylindrical portions be part of the entrapped rocker element. Rather, one of those male portions could be on the bearing adapter, and one of those male portions could be on the pedestal seat, with the corresponding female portions being formed on the entrapped rocker element. In the further alternative, the rocker element could include one male element, and one female element, having the male element formed on <b>r₁</b> (or <b>r₂)</b> being located on the bearing adapter, and the female element formed on <b>R₁</b> (or <b>R₂)</b> being on the underside of the entrapped rocker element, and the male element formed on <b>r₂</b> (or <b>r₁)</b> being formed on the upper surface of the entrapped rocker element, and the respective mating female element formed on radius <b>R₂</b> (or <b>R₁)</b> being formed on the lower face of the pedestal seat. In the still further alternative, the rocker element could include one male element, and one female element, having the male element formed on <b>r₁</b> (or <b>r₂)</b> being located on the pedestal seat, and the female element formed on <b>R₁</b> (or <b>R₂)</b> being on the upper surface of the entrapped rocker element, and the male element formed on <b>r₂</b> (or <b>r₁)</b> being formed on the lower surface of the entrapped rocker element, and the respective mating female element formed on radius <b>R₂</b> (or <b>R₁)</b> being formed on the upper face of the bearing adapter. There are, in this regard, at least eight combinations as represented in <figref idref="f0023">Figure <b>17e</b></figref> by assemblies <b>601, 603, 605, 607, 611, 613, 615,</b> and <b>617.</b>

The embodiment of <figref idref="f0022 f0023 f0024 f0025 f0026 f0027 f0028 f0029 f0030 f0031 f0032 f0033 f0034">Figures <b>17a -17d</b></figref> may tend to yield line contact at the force transfer interfaces, and yet rock in both the longitudinal and lateral directions, with compliance to torsion about the vertical axis. That is, the bearing adapter to pedestal seat interface assembly may tend to permit rotation about the longitudinal axis to give lateral rocking motion of the side frame; rotation about a transverse axis to give longitudinal rocking motion; and compliance to torsion about the vertical axis. It may tend to discourage lateral translation, and may tend to retain high stiffness in the vertical direction.

Figures <b>18a</b> and <b>18b</b>

The embodiment of <figref idref="f0021">Figures <b>18a</b> and <b>18b</b></figref> is substantially similar to the embodiment of <figref idref="f0022 f0023 f0024 f0025 f0026 f0027 f0028 f0029 f0030 f0031 f0032 f0033 f0034">Figures <b>17a</b> to <b>17d</b></figref><b>.</b> However, rather than employing a pivot connection such as the bore, stub, bushing and bearing of <figref idref="f0022 f0023 f0024 f0025 f0026 f0027 f0028 f0029 f0030 f0031 f0032 f0033 f0034">Figures <b>17a -17d</b></figref><b>,</b> a rocker element <b>644</b> is captured between bearing adapter <b>600</b> and pedestal seat <b>604.</b> Rocker element <b>644</b> has a torsional compliance element made of a resilient material, identified as elastomeric member <b>646</b> bonded between the opposed faces of the upper <b>647</b> and lower <b>645</b> portions of rocker element <b>644.</b> Although <figref idref="f0021">Figures <b>18a</b> and <b>18b</b></figref> show the laterally extending trough in bearing adapter <b>600,</b> and the longitudinal trough in pedestal seat <b>604,</b> the same permutations of <figref idref="f0010">Figure <b>7e</b></figref> may be made. In general, while the torsional element may be between the two cylindrical elements in a manner tending torsionally to decouple them, it may be that the elastomeric pad need not necessarily be installed between the two cylindrical members. For example, the rocker element <b>644</b> may be solid, and an elastomeric element may be installed beneath the top surface of bearing adapter <b>600,</b> or above the pedestal seat element, such that a torsionally compliant element is placed in series with the two rockers.

The same general commentary may be made with regard to the pivotal connection suggested above in connection with the example of <figref idref="f0022 f0023 f0024 f0025 f0026 f0027 f0028 f0029 f0030 f0031 f0032 f0033 f0034">Figures <b>17a</b> to <b>17d</b></figref><b>.</b> That is, the top of the bearing adapter could be pivotally mounted to the body of the bearing adapter more generally, or the pedestal seat could be pivotally mounted to the pedestal roof, such that a torsionally compliant element would be in series with the two rockers. However, as noted above, the torsionally compliant element may be between the two rockers, such that they may tend to be torsionally de-coupled from each other. In general, with regard to the embodiments of <figref idref="f0022 f0023 f0024 f0025 f0026 f0027 f0028 f0029 f0030 f0031 f0032 f0033 f0034">Figures <b>17a - 17d</b></figref><b>,</b> and <b>18a - 18b,</b> provided that the radii employed yield a physically appropriate combination tending toward a local stable minimum energy state, the male portion of the bearing adapter to pedestal seat interface (with the smaller radius of curvature) may be on either the bearing adapter or on the pedestal seat, and the mating female portion (with the larger radius of curvature) may be on the other part, whichever it may be. In that light, although a particular depiction may show a male portion on a bearing adapter, and a female fitting on the pedestal seat, these features may, in general, be reversed.

Figures <b>19a</b> to <b>19c, 20a</b> to <b>20c,</b> and <b>21a</b> to <b>21g</b>

<figref idref="f0024 f0025">Figures <b>19a</b> to <b>19c</b></figref> show the combination of a bearing adapter <b>650</b> with an elastomeric bearing adapter pad <b>652</b> and a rocker <b>654</b> and pedestal seat <b>656</b> to permit lateral rocking of the sideframe. Bearing adapter <b>650,</b> shown in three additional views in <figref idref="f0026">Figures 20a - 20c</figref> is substantially similar to bearing adapter <b>44</b> (or <b>144)</b> to the extent of its geometric features for engaging a bearing, but differs therefrom in having a more or less conventional upper surface. Upper surface <b>658</b> may be flat, or may have a large (roughly 60") radius crown <b>660,</b> such as might have been used for engaging a planar pedestal seat surface. Crown <b>660</b> is split into two fore-and-aft portions, with a laterally extending central flat portion between them. Abreast of the central flat portion, bearing adapter <b>650</b> has a pair of laterally proud, outwardly facing lateral lands, <b>662</b> and <b>664,</b> and, amidst those lands, lateral lugs <b>666</b> that extend further still proud beyond lands <b>662</b> and <b>664.</b>

Bearing adapter pad <b>652</b> may be a commercially available assembly such as may be manufactured by Lord Corporation of Erie Pennsylvania, or such as may be identified as Standard Car Truck Part Number SCT 5844. Bearing adapter pad <b>652</b> has a bearing adapter engagement member in the nature of a lower plate <b>668</b> whose bottom surface <b>670</b> is relieved to seat over crown <b>660</b> in non-rocking engagement. Lateral and longitudinal translation of bearing adapter pad <b>652</b> is inhibited by an array of downwardly bent securement locating lugs, or fingers, or claws, in the nature of indexing members or tangs <b>672,</b> two per side in pairs located to reach downwardly and bracket lugs <b>666</b> in close fitting engagement. The bracketing condition with respect to lugs <b>666</b> inhibits longitudinal motion between bearing adapter pad <b>652</b> and bearing adapter <b>650.</b> The laterally inside faces of tangs <b>672</b> closely oppose the laterally outwardly facing surfaces of lands <b>662</b> and <b>664,</b> tending thereby to inhibit lateral relative motion of bearing adapter pad <b>652</b> relative to bearing adapter <b>650.</b> The vertical, lateral, and longitudinal position relative to bearing adapter <b>650</b> can be taken as fixed.

Bearing adapter pad <b>652</b> also has an upper plate, <b>674,</b> that, in the case of a retro-fit installation of rocker <b>654</b> and seat <b>656,</b> may have been used as a pedestal seat engagement member. In any case, upper plate <b>674</b> has the general shape of a longitudinally extending channel member, with a central, or back, portion, <b>676</b> and upwardly extending left and right hand leg portions <b>678, 680</b> adjoining the lateral margins of back portion <b>676.</b> Leg portions <b>678</b> may have a size and shape such as might have been suitable for mounting directly to the sideframe pedestal.

Between lower plate <b>668</b> and upper plate <b>674,</b> bearing adapter pad <b>652</b> has a bonded resilient sandwich <b>680</b> that may include a first resilient layer, indicated as lower elastomeric layer <b>682</b> mounted directly to the upper surface of lower plate <b>668,</b> an intermediate stiffener shear plate <b>684</b> bonded or molded to the upper surface of layer <b>682,</b> and an upper resilient layer, indicated as upper elastomeric layer <b>686</b> bonded atop plate <b>684.</b> The upper surface of layer <b>686</b> may be bonded or molded to the lower surface of upper plate <b>674.</b> Given that the resilient layers may be quite thin as compared to their length and breadth, the resultant sandwich may tend to have comparatively high vertical stiffness, comparatively high resistance to torsion about the longitudinal (x) and lateral (y) axes, comparatively low resistance to torsion about the vertical (z) axis (given the small angular displacements in any case), and non-trivial, roughly equal resistance to shear in the x or y directions that may be in the range of 20,000 to 40,000 lbs per inch, or more narrowly, about 30,000 lbs per inch for small deflections. Bearing adapter pad <b>652</b> may tend to permit a measure of self steering to be obtained when the elastomeric elements are subjected to longitudinal shear forces.

Rocker <b>654</b> (seen in additional views <b>21e, 21f</b> and <b>21g)</b> has a body of substantially constant cross-section, having a lower surface <b>690</b> formed to sit in substantially flat, non-rocking engagement upon the upper surface of plate <b>674</b> of bearing adapterpad <b>652,</b> and an upper surface <b>692</b> formed to define a male rocker surface. Upper surface <b>692</b> may have a continuously radius central portion <b>694</b> lying between adjacent tangential portions <b>696</b> lying at a constant slope angle. In one embodiment, the central portion may describe 4 - 6 degrees of arc to either side of a central position, and may, in one embodiment have about 4-½ to 5 degrees. In the terminology used above, this radius is "<b>r₂</b>", the male radius of a lateral rocker for permitting lateral swinging motion of side frame <b>26.</b> Where a bearing adapter with a crown radius is mounted under the resilient bearing adapter pad, the radius of rocker <b>654</b> is less than the radius of the crown, perhaps less than half the crown radius, and possibly being less than 1/3 of the crown radius. It may be formed on a radius of between 5 and 20 inches, or, more narrowly, on a radius of between 8 and 15 inches. Surface <b>692</b> could also be formed on a parabolic profile, an elliptic or hyperbolic profile, or some other profile to yield lateral rocking.

Pedestal seat <b>656</b> (seen in <figref idref="f0027">Figures <b>21a</b> to <b>21d</b></figref><b>)</b> has a body having a major portion <b>700</b> that is substantially rectangular in plan view. When viewed from one end in the longitudinal direction, pedestal seat <b>656</b> has a generally channel shaped cross-section, in which major portion <b>700</b> forms the back <b>702</b> and two longitudinally running legs <b>704, 706</b> extend upwardly and laterally outwardly from the lateral margins of major portion <b>700.</b> Legs <b>704</b> and <b>706</b> have an inner, or proximal portion <b>708</b> that extends upwardly and outwardly at an angle from the lateral margins of main portion <b>700,</b> and an outer, or distal portion, or toe <b>710</b> that extends from the end of proximal portion <b>708</b> in a substantially vertical direction. The breadth between the opposed fingers of the channel section (i.e., between opposed toes <b>710)</b> corresponds to the width of the sideframe pedestal roof <b>712,</b> as shown in the cross-section of <figref idref="f0024">Figure 19b</figref>, with which legs <b>704</b> and <b>706</b> sit in close fitting, bracketing engagement. Legs <b>704</b> and <b>706</b> have longitudinally centrally located cut-outs, reliefs, rebates, or indexing features, identified as notches <b>714.</b> Notches <b>714</b> seat in close fitting engagement about T-shaped lugs <b>716</b> (<figref idref="f0024">Figure 19b</figref>) that are welded to the sideframe on either side of the pedestal roof. This engagement establishes the lateral and longitudinal position of pedestal seat <b>656</b> with respect to sideframe <b>26.</b>

Pedestal seat <b>656</b> also has four laterally projecting corner lugs, or abutment fittings <b>718,</b> whose longitudinally inwardly facing surfaces oppose the laterally extending end-face surfaces of the upturned legs <b>678</b> of upper plate <b>674</b> of bearing adapter pad <b>652.</b> That is, the corner abutment fittings <b>718</b> on either lateral side of pedestal seat <b>656</b> bracket the ends of the upturned legs <b>678</b> of adapter pad <b>652</b> in close fitting engagement. This relationship fixes the longitudinal position of pedestal seat <b>656</b> relative to the upper plate of bearing adapter pad <b>652.</b>

Major portion <b>700</b> of pedestal seat <b>656</b> has a downwardly facing surface <b>700</b> that is hollowed out to form a depression defining a female rocking engagement surface <b>702.</b> This surface is formed on a female radius (identified as <b>R₂</b> in concordance with terminology used herein above) that is quite substantially larger than the radius of central portion <b>694</b> (<figref idref="f0027">Figure <b>21f</b></figref><b>)</b> of rocker <b>654,</b> such that rocker <b>654</b> and pedestal seat <b>656</b> meet in rolling line contact engagement and permit sideframe <b>26</b> to swing laterally in a lateral rocking relationship on rocker <b>654.</b> The arcuate profile of female rocking engagement surface <b>702</b> may be such as to encourage lateral self centering of rocker <b>654,</b> and may have a radius of curvature that varies from a central region to adjacent regions, which may be tangential planar regions. Where pedestal seat <b>656</b> and rocker <b>654</b> are provided by way of retro-fit installation above an adapter having a crown radius, the radius of curvature of the pedestal seat may tend to be less than or equal to the crown radius. The central radius of curvature <b>R₂</b> of surface <b>702,</b> or the radius of curvature generally if constant, may be in the range of 6 to 60 inches, is preferably greater than 10 inches and less than 40 inches. It may be between 11/10 to 4 times as large as the rocker radius of curvature r₂. As noted elsewhere, the pedestal seat need not have the female rocker surface, and the rocker need not have the male rocker surface, but rather, these surfaces could be reversed, so that the male surface is on the pedestal seat, and the female surface is on the rocker. Particularly in the context of a retro-fit installation, there may be relatively little clearance between the upturned legs <b>678</b> of upper plate <b>674</b> and legs <b>704, 706</b> of pedestal seat <b>656.</b> This distance is shown in <figref idref="f0024">Figure <b>19b</b></figref> as gap <b>'G',</b> which is preferably sufficient allowance for rocking motion between the parts that rocking motion is bounded by the spacing of the truck bolster gibs <b>106, 108.</b>

By providing the combination of a lateral rocker and a shear pad, the resultant assembly may provide a generally increased softness in the lateral direction, while permitting a measure of self steering. The example of <figref idref="f0024">Figure <b>19a</b></figref> may be provided as an original installation, or may be provided as a retrofit installation. In the case of a retrofit installation, rocker <b>654</b> and pedestal seat <b>656</b> may be installed between an existing elastomeric pad and an existing pedestal seat, or may be installed in addition to a replacement elastomeric pad of lesser through-thickness, such that the overall height of the bearing adapter to pedestal seat interface may remain roughly the same as it was before the retrofit.

<figref idref="f0026">Figures <b>19e</b> and <b>19f</b></figref> represent alternate embodiments of combinations of elastomeric pads and rockers. While the embodiment of <figref idref="f0024">Figure <b>19a</b></figref> showed an elastomeric sandwich that had roughly equivalent response to shear in the lateral and longitudinal directions, this need not be the general case. For example, in the embodiments of <figref idref="f0026">Figures <b>19e</b> and <b>19f</b></figref><b>,</b> elastomeric bearing adapter pad assemblies <b>720</b> and <b>731</b> have respective resilient elastomeric laminates sandwiches, indicated generally as <b>722</b> and <b>723</b> in which the stiffeners <b>726, 727</b> have longitudinally extending corrugations, or waves. In the longitudinal direction, the sandwich may tend to react in nearly pure shear, as before in the example of <figref idref="f0024">Figure 19a</figref>. However, deflection in the lateral direction now requires not only a shear component, but also a component normal to the elastomeric elements, in compressive or tensile stress, rather than, and in addition to, shear. This may tend to give a stiffer lateral response, and hence an anisotropic response. An anisotropic shear pad arrangement of this nature might have been used in the embodiment of <figref idref="f0024">Figure 19a</figref>, and a planar arrangement, as in the embodiment of <figref idref="f0024">Figure 19a</figref> could be used in either of the embodiments of <figref idref="f0026">Figures <b>19e,</b> and <b>19f</b></figref><b>.</b> Considering <figref idref="f0026">Figure <b>19e</b></figref><b>,</b> both base plate <b>728</b> and upper plate <b>730</b> has a wavy contour corresponding to the wavy contour of sandwich <b>722</b> generally. Rocker <b>732</b> has a lower surface of corresponding profile. Otherwise, this embodiment is substantially the same as the embodiment of <figref idref="f0024">Figure <b>19a</b></figref><b>.</b>

Considering <figref idref="f0026">Figure <b>19f</b></figref><b>,</b> an elastomeric bearing adapter pad assembly <b>721</b> has a base plate <b>734</b> having a lower surface for seating in non-rocking relationship on a bearing adapter, in the same manner as bearing adapter pad assembly <b>652</b> sits upon bearing adapter <b>650.</b> The upper surface <b>735</b> of base plate <b>734</b> has a corrugated or wavy contour, the corrugations running lengthwise, as discussed above. An elastomeric laminate of a first resilient layer <b>736,</b> an internal stiffener plate <b>737,</b> and a second resilient layer <b>738</b> are located between base plate <b>734</b> and a correspondingly wavy undersurface of upper plate <b>740.</b> Rather than being a flat plate upon which a further rocker plate is mounted, upper plate <b>740</b> has an upper surface <b>742</b> having an integrally formed rocker contour corresponding to that of the upper surface of rocker <b>654.</b> Pedestal seat <b>744</b> then mounts directly to, and in lateral rocking relationship with upper plate <b>740,</b> without need for a separate rocker part. The combination of bearing adapter pad <b>721</b> and pedestal seat <b>742</b> may have interconnecting abutments <b>747</b> to prevent longitudinal migration of rocker surface <b>742</b> relative to the contoured downwardly facing surface <b>748</b> of pedestal seat <b>744.</b>

Figures <b>22a to 22c, 23a and 23b</b>

Rather than employ a bearing adapter that is separate from the bearing, <figref idref="f0028">Figures <b>22a</b> to <b>22c</b></figref> show a bearing <b>750</b> mounted on one of the end of an axle <b>752.</b> Bearing <b>750</b> has an integrally formed arcuate rolling contact surface <b>754</b> for mating rolling point contact with a mating rolling contact surface <b>756</b> of a pedestal seat fitting <b>758.</b> The general geometry of the rolling relationship is as described above in terms of the possible relationships of <b>r₁, R₁</b> and <b>L</b>, and, as noted above, the male and female rolling contact surfaces can be reversed, such that the male surface is on the pedestal seat, and the female surface is on the bearing, or further still, in the case of a compound curvature, the surfaces made be saddle shaped, as described above. The bearing illustrations of <figref idref="f0029">Figures <b>22b</b></figref> and <figref idref="f0030"><b>23b</b></figref> are based on the bearing cross-section illustration shown on page 812 of the <i>1997 Car and Locomotive Cyclopedia.</i> That illustration was provided to the <i>Cyclopedia</i> courtesy of Brenco Inc., of Petersburg, Virginia.

In greater detail, bearing <b>750</b> is an assembly of parts including an inner ring <b>760,</b> a pair of tapered roller assemblies <b>762</b> whose inner ring engages axle <b>752,</b> and an outer ring member <b>764</b> whose inner frustoconical bearing surfaces engage the rollers of assemblies <b>762.</b> The entire assembly, including seals, spacers, and backing ring is held in place by an end cap <b>766</b> mounted to the end of axle <b>752.</b> In the assembly of <figref idref="f0028">Figures <b>22a</b> to <b>22c</b></figref><b>,</b> does not employ a round cylindrical outer ring member, but rather, ring member <b>764</b> is made with an upper portion <b>770</b> having the same general shape and function as bearing adapter <b>44</b> or <b>144,</b> including tapered end walls <b>768</b> for rocking motion travel limiting abutment against the surfaces of the pedestal jaws <b>130</b> as described above. Further, upper portion <b>770</b> includes corner abutments <b>774</b> for bracketing jaws <b>130,</b> again, as described above. Thus a bearing is provided with an integrally formed rocking surface. The rocking surface is permanently fixed with relation to the remainder of the underlying bearing assembly. In this way, an assembly is provided in which rotation of the bearing housing is inhibited relative to the rocking surface.

In <figref idref="f0030">Figures <b>23a</b> and 23b</figref>, an integrated bearing and bearing adapter rocker assembly, or wheelset to pedestal interface assembly, is indicated as modified bearing <b>790.</b> In this case the outer ring <b>792</b> has been formed in the shape of a laterally extending, cylindrical rocker surface <b>794,</b> such as a male surface (although it could be female as discussed above), for engaging the mating female (although, as discussed, it could be male) laterally rocker surface <b>796</b> of pedestal seat <b>798,</b> such as may tend to provide weight-proportional self steering, as discussed above.

Thus, the embodiments of <figref idref="f0028">Figures <b>22a</b></figref> and <figref idref="f0030"><b>23a</b></figref> both show a sideframe pedestal to axle bearing interface assembly for a three piece rail road car truck. The assembly of the embodiment of <figref idref="f0028">Figure 22a</figref> has fittings that are operable to rock both laterally and longitudinally. Both embodiments include bearing assemblies having one of the rocking surface fittings, whether male or female, of saddle shape, formed as an integral portion of the outer ring of the bearing, such that the location of the rolling contact surface is rigidly located relative to the bearing (because, in this instance, it is part of the bearing). In the embodiment of <figref idref="f0028">Figure <b>22a</b></figref><b>,</b> the integrally firmed surface is a compound surface, whereas in the embodiment of <figref idref="f0030">Figure <b>23b</b></figref><b>,</b> the rolling contact surface is a cylindrical surface, which may be formed on an arc of constant radius of curvature.

The possible permutations of surface types include those indicated above in terms of a two element interface (i.e., the rocking surface on the top of the bearing, and the mating rocking surface on the pedestal seat) or a three element interface, in which an intermediate rocking member is mounted between (a) the surface rigidly located with respect to the bearing races, and (b) the surface of the pedestal seat. As above, one or another of the surfaces may be formed on a spherical arc portion such that the fittings are torsionally compliant, or, put alternatively, torsionally de-coupled with respect to rotation about the vertical axis. The permutations may also include the use of resilient pads such as members <b>156, 374, 412,</b> or <b>456,</b> as may be appropriate.

Each of the assemblies of <figref idref="f0028">Figures <b>22a</b></figref> and <figref idref="f0030"><b>23a</b></figref> has a bearing for mounting to one end of an axle of a wheelset of a three-piece railroad car truck. The bearing has an outer member mounted in a position to permit the end of the axle to rotate relative thereto, inasmuch as the inner ring is intended to rotate with respect to the outer ring. The bearing has an axis of rotation, about which its rings and bearings are concentric that, when installed, may tend to be coincident with the longitudinal axis of the axis of the axle of the wheelset. In each case, the outer member has a rocking surface formed thereon for engaging a mating rolling contact surface of a pedestal seat member of a sideframe of the three piece truck.

The rolling contact surface of the bearing has a local minimum energy condition when centered under the corresponding seat, and it is preferred that the mating rolling contact surface be given a radius that may tend to encourage self centering of the male rolling contact element. That is to say, displacement from the minimum energy position (preferably the centered position) may tend to cause the vertical separation distance between the centerline of the wheelset axis (and hence the centreline of the axis of rotation of the bearing) to become more distantly spaced from the sideframe pedestal roof, since the rocking action may tend marginally to raise the end of the sideframe, thus increasing the stored potential energy in the system.

This can be expressed differently. In cylindrical polar co-ordinates, the long axis of the wheelset axle may be considered as the axial direction. There is a radial direction measured perpendicularly away from the axial direction, and there is an angular circumferential direction that is mutually perpendicular to both the axial direction, and the radial direction. There is a location on the rolling contact surface that is closer to the axis of rotation of the bearing than any other location. This defines the "rest" or local minimum potential energy equilibrium position. Since the radius of curvature of the rolling contact surface is greater than the radial length, <b>L</b>, between the axis of rotation of the bearing and the location of minimum radius, the radial distance, as a function of circumferential angle <b>θ</b> will increase to either side of the location of minimum radius (or, put alternatively, the location of minimum radial distance from the axis of rotation of the bearing lies between regions of greater radial distance). Thus the slope of the function <b>r(θ),</b> namely <b>dr/dθ,</b> is zero at the minimum point, and is such that r increases at an angular displacement away from the minimum point to either side of the location of minimum potential energy. Where the surface has compound curvature, both <b>dr/dθ</b> and <b>dr/dL</b> are zero at the minimum point, and are such that r increases to either side of the location of minimum energy to all sides of the location of minimum energy, and zero at that location. This may tend to be true whether the rolling contact surface on the bearing is a male surface or a female surface or a saddle, and whether the center of curvature lies below the center of rotation of the bearing, or above the rolling contact surfaces. The curvature of the rolling contact surface may be spherical, ellipsoidal, toroidal, paraboloid, parabolic or cylindrical. The rolling contact surface has a radius of curvature, or radii of curvature, if a compound curvature is employed, that is, or are, larger than the distance from the location of minimum distance from the axis of rotation, and the rolling contact surfaces are not concentric with the axis of rotation of the bearing.

Another way to express this is to note that there is a first location on the rolling contact surface of the bearing that lies radially closer to the axis of rotation of the bearing than any other location thereon. A first distance, <b>L</b> is defined between the axis of rotation, and that nearest location. The surface of the bearing and the surface of the pedestal seat each have a radius of curvature and mate in a male and female relationship, one radius of curvature being a male radius of curvature <b>r₁,</b> the other radius of curvature being a female radius of curvature, <b>R₂,</b> (whichever it may be). <b>r₁</b> is greater than <b>L, R₂</b> is greater than <b>r₁,</b> and <b>L, r₁</b> and <b>R₂</b> conform to the formula <b>L^-1 - (r₁-¹ - R₂-¹)</b> &gt; 0, the rocker surfaces being co-operable to permit self steering.

Figures <b>24a</b> to <b>24e</b>

<figref idref="f0031 f0032 f0033 f0034">Figures <b>24a</b> to <b>24e</b></figref> relate to a three piece truck <b>200.</b> Truck <b>200</b> has three major elements, those elements being a truck bolster <b>192,</b> that is symmetrical about the truck longitudinal centreline, and a pair of first and second side frames, indicated as <b>194.</b> Only one side frame is shown in <figref idref="f0019">Figure <b>14c</b></figref> given the symmetry of truck <b>200.</b> Three piece truck <b>200</b> has a resilient suspension (a primary suspension) provided by a spring groups <b>195</b> trapped between each of the distal (i.e., transversely outboard) ends of truck bolster <b>192</b> and side frames <b>194.</b>

Truck bolster <b>192</b> is a rigid, fabricated beam having a first end for engaging one side frame assembly and a second end for engaging the other side frame assembly (both ends being indicated as <b>193).</b> A center plate or center bowl <b>190</b> is located at the truck center. An upper flange <b>188</b> extends between the two ends <b>194,</b> being narrow at a central waist and flaring to a wider transversely outboard termination at ends <b>194.</b> Truck bolster <b>192</b> also has a lower flange <b>189</b> and two fabricated webs <b>191</b> extending between upper flange <b>188</b> and lower flange <b>189</b> to form an irregular, closed section box beam. Additional webs <b>197</b> are mounted between the distal portions of flanges <b>188</b> and <b>189</b> where bolster <b>192</b> engages one of the spring groups <b>195.</b> The transversely distal region of truck bolster <b>192</b> also has friction damper seats <b>196, 198</b> for accommodating friction damper wedges.

Side frame <b>194</b> may be a casting having pedestal fittings <b>40</b> into which bearing adapters <b>44,</b> bearings <b>46,</b> and a pair of axles <b>48</b> and wheels <b>50</b> mount. Side frame <b>194</b> also has a compression member, or top chord member <b>32,</b> a tension member, or bottom chord member <b>34,</b> and vertical side columns <b>36</b> and <b>36,</b> each lying to one side of a vertical transverse plane bisecting truck <b>200</b> at the longitudinal station of the truck center. A generally rectangular opening is defined by the co-operation of the upper and lower beam members <b>32, 34</b> and vertical sideframe columns <b>36,</b> into which end <b>193</b> of truck bolster <b>192</b> can be introduced. The distal end of truck bolster <b>192</b> can then move up and down relative to the side frame within this opening. Lower beam member <b>34</b> has a bottom or lower spring seat <b>52</b> upon which spring group <b>195</b> can seat. Similarly, an upper spring seat <b>199</b> is provided by the underside of the distal portion of bolster <b>192</b> which engages the upper end of spring group <b>195.</b> As such, vertical movement of truck bolster <b>192</b> will tend to increase or decrease the compression of the springs in spring group <b>195.</b>

In the embodiment of <figref idref="f0031">Figure <b>24a</b></figref><b>,</b> spring group <b>195</b> has two rows of springs <b>193,</b> a transversely inboard row and a transversely outboard row. In one embodiment each row may have four large (8 inch +/-) diameter coil springs giving vertical bounce spring rate constant, <b>k,</b> for group <b>195</b> of less than 10,000 lbs. / inch. In one embodiment this spring rate constant may be in the range of 6000 to 10,000 lbs. / in., and may be in the range of 7000 to 9500 lbs. / in, giving an overall vertical bounce spring rate for the truck of double these values, perhaps in the range of 14,000 to 18,500 lbs. / in for the truck. The spring array may include nested coils of outer springs, inner springs, and inner-inner springs depending on the overall spring rate desired for the group, and the apportionment of that stiffness. The number of springs, the number of inner and outer coils, and the spring rate of the various springs can be varied. The spring rates of the coils of the spring group add to give the spring rate constant of the group, typically being suited for the loading for which the truck is designed.

Each side frame assembly also has four friction damper wedges arranged in first and second pairs of transversely inboard and transversely outboard wedges <b>204, 205, 206</b> and <b>207</b> that engage the sockets, or seats <b>196, 198</b> in a four-cornered arrangement. The corner springs in spring group <b>195</b> bear upon a friction damper wedge <b>204, 205, 206</b> or <b>207.</b> Each vertical column <b>36</b> has a friction wear plate <b>92</b> having transversely inboard and transversely outboard regions against which the friction faces of wedges <b>204, 205, 206</b> and <b>207</b> can bear, respectively. Bolster gibs <b>106</b> and <b>108</b> lie inboard and outboard of wear plate <b>92</b> respectively.

In the illustration of <figref idref="f0031">Figure <b>24e</b></figref><b>,</b> the damper seats are shown as being segregated by a partition <b>208.</b> If a longitudinal vertical plane is drawn through truck <b>200</b> through the center of partition <b>208,</b> it can be seen that the inboard dampers lie to one side of plane <b>209,</b> and the outboard dampers lie to the outboard side of the plane. In hunting then, the normal force from the damper working against the hunting will tend to act in a couple in which the force on the friction bearing surface of the inboard pad will always be fully inboard of the plane on one end, and fully outboard on the other diagonal friction face.

In one embodiment, the size of the spring group embodiment of <figref idref="f0031">Figure 24b</figref> may yield a side frame window opening having a width between the vertical columns <b>36</b> of side frame <b>194</b> of roughly 33 inches. This is relatively large compared to existing spring groups, being more than 25 % greater in width. In the embodiment of <figref idref="f0003">Figure 1f</figref> truck <b>20</b> may also have an abnormally wide sideframe window to accommodate 5 coils each of 5½" dia. Truck <b>200</b> may have a correspondingly greater wheelbase length, indicated as <b>WB. WB</b> may be greater than 73 inches, or, taken as a ratio to the track gauge width, may be greater than 1.30 time the track gauge width. It may be greater than 80 inches, or more than 1.4 times the gauge width, and in one embodiment is greater than 1.5 times the track gauge width, being as great, or greater than, about 84 inches. Similarly, the side frame window may be wider than tall. The measurement across the wear plate faces between the opposed side frame columns <b>36</b> may be greater than 24", possibly in the ratio of greater than 8:7 of width to height, and possibly in the range of 28" or 32" or more, giving ratios of greater than 4:3 and greater than 3:2. The spring seat may have lengthened dimensions to correspond to the width of the side frame window, and a transverse width of 15 ½ - 17" or more.

Figures <b>25a</b> to <b>25d</b>

<figref idref="f0032">Figures <b>25a</b> to <b>25d</b></figref><b>,</b> show an alternate truck embodiment. Truck <b>800</b> has a bolster <b>808,</b> side frame <b>807</b> and damper <b>801, 802</b> installation that employs constant force inboard and outboard, fore and aft pairs of friction dampers <b>801, 802</b> independently sprung on horizontally acting springs <b>803, 804</b> housed in side-by-side pockets <b>805, 806</b> mounted in the ends of truck bolster <b>808.</b> While only two dampers <b>801, 802</b> are shown, a pair of such dampers faces toward each of the opposed side frame columns. Dampers <b>801, 802</b> may each include a block <b>809</b> and a consumable wear member <b>810</b> mounted to the face of block <b>809.</b> The block and wear member have mating male and female indexing features <b>812</b> to maintain their relative position. A removable grub screw fitting <b>814</b> is provided in the spring housing to permit the spring to be pre-loaded and held in place during installation. Spring s <b>803, 804</b> urge, or bias, friction dampers <b>801, 802</b> against the corresponding friction surfaces of the sideframe columns. The deflection of springs <b>803, 804</b> does not depend on compression of the main spring group <b>816,</b> but rather is a function of an initial pre-load.

Figures <b>26a</b> and <b>26b</b>

<figref idref="f0033">Figures <b>26a</b> and <b>26b</b></figref> show a partial isometric view of a truck bolster <b>820</b> that is generally similar to truck bolster <b>402</b> of <figref idref="f0019">Figure <b>14a</b></figref><b>,</b> except insofar as bolster pocket <b>822</b> does not have a central partition like web <b>452,</b> but rather has a continuous bay extending across the width of the underlying spring group, such as spring group <b>436.</b> A single wide damper wedge is indicated as <b>824.</b> Damper <b>824</b> is of a width to be supported by, and to be acted upon, by two springs <b>825, 826</b> of the underlying spring group. In the event that bolster <b>400</b> may tend to deflect to a non-perpendicular orientation relative to the associated side frame, as in the parallelogramming phenomenon, one side of wedge <b>824</b> may tend to be squeezed more tightly than the other, giving wedge <b>824</b> a tendency to twist in the pocket about an axis of rotation perpendicular to the angled face (i.e., the hypotenuse face) of the wedge. This twisting tendency may also tend to cause differential compression in springs <b>825, 826,</b> yielding a restoring moment both to the twisting of wedge <b>824</b> and to the non-square displacement of truck bolster <b>820</b> relative to the truck side frame. There may tend to be a similar moment generated at the opposite spring pair at the opposite side column of the side frame. <figref idref="f0033">Figure 26b</figref> shows an alternate pair of damper wedges <b>827, 828.</b> This dual wedge configuration can similarly seat in bolster pocket <b>822,</b> and, in this case, each wedge <b>827, 828</b> sits over a separate spring. Wedges <b>827, 828</b> are slidable relative to each other along the primary angle of the face of bolster pocket <b>822.</b> When the truck moves to an out of square condition, differential displacement of wedges <b>827, 828</b> may tend to result in differential compression of their associated springs, e.g., <b>825, 826</b> resulting in a restoring moment. In either case, the bolster pockets may have wear liners <b>494,</b> and the pockets themselves may be part of prefabricated inserts <b>506</b> to be welded to the end of the bolster, either at original manufacture or retro-fit, such as might include installation of wider sideframe columns, and a different spring group selection such as might accompany a retrofit conversion from a single damper to a double damper (i.e., four cornered) arrangement.

Figures <b>27a</b> and <b>27b</b>

<figref idref="f0034">Figure <b>27a</b></figref> shows a bolster <b>830</b> that is similar to bolster <b>210</b> except insofar as bolster pockets <b>831, 832</b> each accommodate a pair of split wedges <b>833, 834.</b> Pockets <b>831, 832</b> each have a pair of bearing surfaces <b>835, 836</b> that are inclined at both a primary angle <b>α</b> and a secondary angle <b>β,</b> the secondary angles of surfaces <b>835</b> and <b>836</b> being of opposite hand to yield the damper separating forces discussed above. Surfaces <b>835</b> and <b>836</b> are also provided with linings in the nature of relatively low friction wear plates <b>837, 838.</b> Each pair of split wedges seats over a single spring.

The example of <figref idref="f0034">Figure 27b</figref> shows a combination of a bolster <b>840</b> and biased split wedges <b>841, 842.</b> Bolster pockets <b>843, 844</b> are stepped pockets in which the steps, e.g., items <b>845, 846,</b> have the same primary angle α, and the same secondary angle β, and are both biased in the same direction, unlike the symmetrical faces of the split wedges in <figref idref="f0034">Figure <b>27a</b></figref><b>,</b> which are left and right handed. Thus the outboard pair of split wedges <b>842</b> has first and second members <b>847, 848</b> each having primary angle α and secondary angle <b>β</b> of the same hand, both members being biased in the outboard direction. Similarly, the inboard pair of split wedges <b>841</b> has first and second members <b>849, 850</b> having primary angle α, and secondary angle <b>β,</b> except that the sense of secondary angle <b>β is</b> such that members <b>849</b> and <b>850</b> tend to be driven in the inboard direction. In the arrangement of <figref idref="f0034">Figures <b>27c</b></figref> a single stepped wedge <b>851, 852</b> may be used in place of the pair of split wedges e.g., members <b>847, 848 or 849, 850.</b> A corresponding wedge of opposite hand is used in the other bolster pocket.

Figures <b>28a</b> and <b>28b</b>

In <figref idref="f0033">Figure <b>28a</b></figref><b>,</b> a truck bolster <b>860</b> has welded bolster pocket inserts <b>861, 862</b> of opposite hands welded into accommodations in its end. Each bolster pocket has inboard and outboard portions 863, 864 that share the same primary angle <b>α</b>, but have secondary angles <b>β</b> that are of opposite hand. Respective inboard and outboard wedges are indicated as <b>865, 866,</b> each seating over a vertically oriented spring <b>867, 868.</b> In this case bolster <b>860</b> is similar to bolster <b>820</b> of <figref idref="f0033">Figure <b>26a</b></figref><b>,</b> to the extent that there is no land separating the inner and outer portions of the bolster pocket. Bolster <b>860</b> is also similar to bolster <b>210</b> of <figref idref="f0008">Figure 5</figref>, except that the bolster pockets of opposite hand are merged without an intervening land. In <figref idref="f0033">Figure <b>28b</b></figref><b>,</b> split wedge pairs <b>869, 870</b> (inboard) and <b>871, 872</b> (outboard) are employed in place of the single inboard and outboard wedges <b>865</b> and <b>866.</b>

Compound Pendulum Geometry

The various rockers shown and described herein may employ rocking elements that define compound pendulums - that is, pendulums for which the male rocker radius is non-zero, and there is an assumption of rolling (as opposed to sliding) engagement with the female rocker. The embodiment of <figref idref="f0004">Figure <b>2a</b></figref> (and others) for example, shows a bi-directional compound pendulum. The performance of these pendulums may affect both lateral stiffness and self-steering on the longitudinal rocker.

The lateral stiffness of the suspension may tend to reflect the stiffness of (a) the sideframe between (i) the bearing adapter and (ii) the bottom spring seat (that is, the sideframes swing laterally); (b) the lateral deflection of the springs between (i) the lower spring seat and (ii) the upper spring seat mounting against the truck bolster, and (c) the moment between (i) the spring seat in the sideframe and (ii) the upper spring mounting against the truck bolster. The lateral stiffness of the spring groups may be approximately ½ of the vertical spring stiffness. For a 100 or 110 Ton truck designed for 263,000 or 286,000 lbs GWR, vertical spring group stiffness might be 25 - 30,000 Lbs./in., assuming two groups per truck, and two trucks per car, giving a lateral spring stiffness of 13 - 16,000 Lbs./in. The second component of stiffness relates to the lateral rocking deflection of the sideframe. The height between the bottom spring seat and the crown of the bearing adapter might be about 15 inches (+/-). The pedestal seat may have a flat surface in line contact on a 60 inch radius bearing adapter crown. For a loaded 286,000 lbs. car, the apparent stiffness of the sideframe due to this second component may be 18,000 - 25,000 Lbs./in, measured at the bottom spring seat. Stiffness due to the third component, unequal compression of the springs, is additive to sideframe stiffness. It may be of the order of 3000 - 3500 Lbs./in per spring group, depending on the stiffness of the springs and the layout of the group. The total lateral stiffness for one sideframe for an S2HD 110 Ton truck may be about 9200 Lbs./inch per side frame.

An alternate truck is the "Swing Motion" truck, such as shown at page 716 in the <i>1980 Car and Locomotive Cyclopedia</i> (1980, Simmons-Boardman, Omaha). In a swing motion truck, the sideframe may act more like a pendulum. The bearing adapter has a female rocker, of perhaps 10 in radius. A mating male rocker mounted in the pedestal roof may have a radius of perhaps 5 in. Depending on the geometry, this may yield a sideframe resistance to lateral deflection in the order of 1/4 (or less) to about ½ of what might otherwise be typical. If combined with the spring group stiffness, the relative softness of the pendulum may be dominant. Lateral stiffness may then be less governed by vertical spring stiffness. Use of a rocking lower spring seat may reduce, or eliminate, lateral stiffness due to unequal spring compression. Swing motion trucks have used transoms to link the side frames, and to lock them against non-square deformation. Other substantially rigid truck stiffening devices such as lateral unsprung rods or a "frame brace" of diagonal unsprung bracing have been used. Lateral unsprung bracing may increase resistance to rotation of the sideframes about the long axis of the truck bolster. This may not necessarily enhance wheel load equalisation or discourage wheel lift.

A formula may be used for estimation of truck lateral stiffness: <maths id="math0001"><math display="block"><msub><mi mathvariant="normal">k</mi><mi>truck</mi></msub><mo mathvariant="normal">=</mo><mn mathvariant="normal">2</mn><mo mathvariant="normal">×</mo><msup><mfenced open="[" close="]"><msup><mfenced><msub><mi mathvariant="normal">k</mi><mi>sideframe</mi></msub></mfenced><mrow><mo mathvariant="normal">-</mo><mn mathvariant="normal">1</mn></mrow></msup><mo mathvariant="normal">+</mo><msup><mfenced><msub><mi mathvariant="normal">k</mi><mi>spring shear</mi></msub></mfenced><mrow><mo mathvariant="normal">-</mo><mn mathvariant="normal">1</mn></mrow></msup></mfenced><mrow><mo mathvariant="normal">-</mo><mn mathvariant="normal">1</mn></mrow></msup></math><img file="EP1997708A2_D0001.tif" /></maths> where <dl id="dl0001" compact="compact"><dt>k_{spring shear}</dt><dd>= The lateral spring constant for the spring group in shear.</dd><dt>k_pendulum</dt><dd>= The force required to deflect the pendulum per unit of deflection, as measured at the center of the bottom spring seat.</dd><dt>k_{spring moment}</dt><dd>= The force required to deflect the bottom spring seat per unit of sideways deflection against the twisting moment caused by the unequal compression of the inboard and outboard springs.</dd></dl>

In a pendulum, the relationship of weight and deflection is roughly linear for small angles, analogous to F = <i>kx,</i> in a spring. A lateral constant can be defined as k_penduium = W / L, where W is weight, and L is pendulum length. An approximate equivalent pendulum length can be defined as L_eq = W / k_pendulum. W is the sprung weight on the sideframe. For a truck having L= 15 and a 60" crown radius, L_eq might be about 3 in. For a swing motion truck, L_eq may be more than double this.

A formula for a longitudinal (i.e., self-steering) rocker as in <figref idref="f0004">Figure 2a</figref>, may also be defined: <maths id="math0002"><math display="block"><mi mathvariant="bold">F</mi><mo mathvariant="bold">/</mo><msub><mi mathvariant="bold">δ</mi><mi mathvariant="bold">long</mi></msub><mo mathvariant="bold">=</mo><msub><mi mathvariant="bold">k</mi><mi mathvariant="bold">long</mi></msub><mo>=</mo><mfenced><mi mathvariant="bold">W</mi><mo mathvariant="bold">/</mo><mi mathvariant="bold">L</mi></mfenced><mo>⁢</mo><mfenced open="[" close="]"><mrow><mo>[</mo><mrow><mo>(</mo><mn>1</mn><mo>/</mo><mi mathvariant="bold">L</mi><mo>)</mo><mo>/</mo><mfenced><mn>1</mn><mo>/</mo><msub><mi mathvariant="bold">r</mi><mn>1</mn></msub><mo>-</mo><mn>1</mn><mo>/</mo><msub><mi mathvariant="bold">R</mi><mn>1</mn></msub></mfenced></mrow><mo>]</mo><mo>-</mo><mn>1</mn></mrow></mfenced></math><img file="EP1997708A2_D0002.tif" /></maths> Where: <ul id="ul0002" list-style="none" compact="compact"><li><b>k_long</b> is the longitudinal constant of proportionality between longitudinal force and longitudinal deflection for the rocker.</li><li><b>F</b> is a unit of longitudinal force, applied at the centerline of the axle</li><li><b>δ_long</b> is a unit of longitudinal deflection of the centreline of the axle</li><li>L is the distance from the centreline of the axle to the apex of male portion 116.</li><li><b>R₁</b> is the longitudinal radius of curvature of the female hollow in the pedestal seat <b>38.</b></li><li><b>r₁</b> is the longitudinal radius of curvature of the crown of the male portion <b>116</b> on the bearing adapter</li></ul>

In this relationship, <b>R₁</b> is greater than <b>r₁,</b> and (1/<b>L</b>) is greater than [(1/<b>r₁) -</b> (1 /<b>R₁</b>)], and, as shown in the illustrations, <b>L</b> is smaller than either <b>r₁</b> or <b>R₁.</b> In some embodiments herein, the length <b>L</b> from the center of the axle to apex of the surface of the bearing adapter, at the central rest position may typically be about 5 - ¾ to 6 inches (+/-), and may be in the range of 5 - 7 inches. Bearing adapters, pedestals, side frames, and bolsters are typically made from steel. The present inventor is of the view that the rolling contact surface may preferably be made of a tool steel, or a similar material.

In the lateral direction, an approximation for small angular deflections is: <maths id="math0003"><math display="block"><msub><mi mathvariant="bold">k</mi><mi mathvariant="bold">pendulum</mi></msub><mo>=</mo><mfenced><msub><mi mathvariant="bold">F</mi><mn mathvariant="bold">2</mn></msub><mo mathvariant="bold">/</mo><msub><mi mathvariant="bold">δ</mi><mn mathvariant="bold">2</mn></msub></mfenced><mo mathvariant="bold">=</mo><mrow><mo mathvariant="bold">(</mo><mi mathvariant="bold">W</mi><mo mathvariant="bold">/</mo><msub><mi mathvariant="bold">L</mi><mi mathvariant="bold">pend</mi></msub><mo mathvariant="bold">)</mo><mfenced open="[" close="]"><mrow><mo mathvariant="bold">[</mo><mrow><mo mathvariant="bold">(</mo><mn>1</mn><mo mathvariant="bold">/</mo><msub><mi mathvariant="bold">L</mi><mrow><mi mathvariant="bold">pend</mi><mn mathvariant="bold">.</mn></mrow></msub><mo mathvariant="bold">)</mo><mo mathvariant="bold">/</mo><mfenced><mfenced><mn>1</mn><mo mathvariant="bold">/</mo><msub><mi mathvariant="bold">R</mi><mi mathvariant="bold">Rocker</mi></msub></mfenced><mo mathvariant="bold">-</mo><mfenced><mn>1</mn><mo mathvariant="bold">/</mo><msub><mi mathvariant="bold">R</mi><mi mathvariant="bold">Seat</mi></msub></mfenced></mfenced></mrow><mo mathvariant="bold">]</mo><mo mathvariant="bold">+</mo><mn>1</mn></mrow></mfenced></mrow></math><img file="EP1997708A2_D0003.tif" /></maths> where: <ul id="ul0003" list-style="none" compact="compact"><li>k_pendulum = the lateral stiffness of the pendulum</li><li><b>F₂</b> = the force per unit of lateral deflection applied at the bottom spring seat</li><li><b>δ₂</b> = a unit of lateral deflection</li><li><b>W</b> = the weight borne by the pendulum</li><li><b>L</b>_pend. = the length of the pendulum, as undeflected, between the contact surface of the bearing adapter to the bottom of the pendulum at the spring seat</li><li><b>R_Rocker</b> = <b>r₂</b> = the lateral radius of curvature of the rocker surface</li><li><b>R</b>_Seat = <b>R₂</b> = the lateral radius of curvature of the rocker seat</li></ul>

Where <b>R</b>_Seat and <b>R_Rocker</b> are of similar magnitude, and are not unduly small relative to <b>L,</b> the pendulum may tend to have a relatively large lateral deflection constant. Where <b>R_Seat</b> is large compared to <b>L</b> or <b>R_Rocker,</b> or both, and can be approximated as infinite (i.e., a flat surface), this formula simplifies to: <maths id="math0004"><math display="block"><msub><mi mathvariant="bold">k</mi><mi>pendulum</mi></msub><mo>=</mo><mfenced><msub><mi mathvariant="bold">F</mi><mi>lateral</mi></msub><mo>/</mo><msub><mi mathvariant="bold">δ</mi><mi>lateral</mi></msub></mfenced><mo>=</mo><mfenced><mi mathvariant="bold">W</mi><mo>/</mo><msub><mi mathvariant="bold">L</mi><mrow><mi>pend</mi><mn>.</mn></mrow></msub></mfenced><mo>⁢</mo><mfenced open="[" close="]"><mrow><mo>(</mo><msub><mi mathvariant="bold">R</mi><mi>Rocker</mi></msub><mo>/</mo><msub><mi mathvariant="bold">L</mi><mi>pendulum</mi></msub><mo>)</mo><mo>+</mo><mn>1</mn></mrow></mfenced></math><img file="EP1997708A2_D0004.tif" /></maths>

Using this number in the denominator, and the design weight in the numerator yields an equivalent pendulum length, L_eq. = W / k_pendulum

The sideframe pendulum may have a vertical length measured (when undeflected) from the rolling contact interface at the upper rocker seat to the bottom spring seat of between 12 and 20 inches, perhaps between 14 and 18 inches. The equivalent length <b>L_eq</b>, may be in the range of greater than 4 inches and less than 15 inches, and, more narrowly, 5 inches and 12 inches, depending on truck size and rocker geometry. Although truck <b>20</b> or <b>22</b> may be a 70 ton special, a 70 ton, 100 ton, 110 ton, or 125 ton truck, truck 20 or 22 may be a truck size having 33 inch diameter, or 36 or 38 inch diameter wheels. In some embodiments herein, the ratio of male rocker radius <b>R_Rocker</b> to pendulum length, <b>L_pend.,</b> may be 3 or less, in some instances 2 or less. In laterally quite soft trucks this value may be less than 1. The factor [ (1 / <b>L_pend.)</b> / ((1 / <b>R_Rocker) -</b> (1 / <b>R_seat</b>))], may be less than 3, and, in some instances may be less than 2_½. In laterally quite soft trucks, this factor may be less than 2. In those various embodiments, the lateral stiffness of the lateral rocker pendulum, calculated at the maximum truck capacity, or the GWR limit for the railcar more generally, may be less than the lateral shear stiffness of the associated spring group. Further, in those various embodiments the truck may be free of lateral unsprung bracing, whether in terms of a transom, laterally extending parallel rods, or diagonally criss-crossing frame bracing or other unsprung stiffeners. In those embodiments the trucks may have four cornered damper groups driven by each spring group.

In the trucks described herein, for their fully laden design condition which may be determined either according to the AAR limit for 70, 100, 110 or 125 ton trucks, or, where a lower intended lading is chosen, then in proportion to the vertical sprung load yielding 2 inches of vertical spring deflection in the spring groups, the equivalent lateral stiffness of the sideframe, being the ratio of force to lateral deflection, measured at the bottom spring seat, may be less than the horizontal shear stiffness of the springs. In some embodiments, particularly for relatively low density fragile, high valued lading such as automobiles, consumer goods, and so on. The equivalent lateral stiffness of the sideframe k_sideframe may be less than 6000 lbs./in. and may be between about 3500 and 5500 lbs./in., and perhaps in the range of 3700 - 4100 lbs./in. For example, in one embodiment a 2 x 4 spring group has 8 inch diameter springs having a total vertical stiffness of 9600 lbs./ in. per spring group and a corresponding lateral shear stiffness k_{spring shear} of 8200 1bs./in. The sideframe has a rigidly mounted lower spring seat. It may be used in a truck with 36 inch wheels. In another embodiment, a 3 x 5 group of 5 ½ inch diameter springs is used, also having a vertical stiffness of about 9600 1bs./in., in a truck with 36 inch wheels. It may be that the vertical spring stiffness per spring group lies in the range of less than 30,000 Ibs./in., that it may be in the range of less than 20,000 lbs./in and that it may perhaps be in the range of 4,000 to 12000 Ibs./in, and may be about 6000 to 10,000 lbs./in. The twisting of the springs may have a stiffness in the range of 750 to 1200 lbs./in. and a vertical shear stiffness in the range of 3500 to 5500 lbs./in. with an overall sideframe stiffness in the range of 2000 to 3500 Ibs./in.

In the embodiments of trucks having a fixed bottom spring seat, the truck may have a portion of stiffness, attributable to unequal compression of the springs equivalent to 600 to 1200 1bs./in. of lateral deflection, when the lateral deflection is measured at the bottom of the spring seat on the sideframe. This value may be less than 1000 Ibs./in., and may be less than 900 Ibs./in. The portion of restoring force attributable to unequal compression of the springs may tend to be greater for a light car as opposed to a fully laden car.

Some embodiments, including those that may be termed swing motion trucks, may have one or more features, namely that, in the lateral swinging direction r/R. &lt; 0.7; 3 &lt; r &lt; 30, or more narrowly, 4 &lt; r &lt; 20; and 5 &lt; R &lt; 45, or more narrowly, 8 &lt; R &lt; 30, and in lateral stiffness, 2,000 lbs/in &lt; kp_endulum &lt; 10,000 lbs/in, or expressed differently, the lateral pendulum stiffness in pounds per inch of lateral deflection at the bottom spring seat where vertical loads are passed into the sideframe, per pound of weight carried by the pendulum, may be in the range of 0.08 and 0.2, or, more narrowly, in the range of 0.1 to 0.16.

Friction Surfaces

Dynamic response may be quite subtle. It is advantageous to reduce resistance to curving, and self steering may help in this regard. It is advantageous to reduce the tendency for wheel lift to occur. A reduction in stick-slip behaviour in the dampers may improve performance in this regard. Employment of dampers having roughly equal upward and downward friction forces may discourage wheel lift. Wheel lift may be sensitive to a reduction in torsional linkage between the sideframes, as when a transom or frame brace is removed. While it may be desirable torsionally to decouple the sideframes it may also be desirable to supplant a physically locked relationship with a relationship that allows the truck to flex in a non-square manner, subject to a bias tending to return the truck to its squared position such as may be obtained by employing the larger resistive moment couple of doubled dampers as compared to single dampers. While use of laterally softy rockers, dampers with reduced stick slip behaviour, four-cornered damper arrangements, and self steering may all be helpful in their own right, it appears that they may also be inter-related in a subtle and unexpected manner. Self steering may function better where there is a reduced tendency to stick slip behaviour in the dampers. Lateral rocking in the swing motion manner may also function better where the dampers have a reduced tendency to stick slip behaviour. Lateral rocking in the swing motion manner may tend to work better where the dampers are mounted in a four cornered arrangement. Counter-intuitively, truck hunting may not worsen significantly when the rigidly locked relationship of a transom or frame brace is replaced by four cornered dampers (apparently making the truck softer, rather than stiffer), and where the dampers are less prone to stick slip behaviour. The combined effect of these features may be surprisingly interlinked.

In the various truck embodiments described herein, there is a friction damping interface between the bolster and the sideframes. Either the sideframe columns or the damper (or both) may have a low or controlled friction bearing surface, that may include a hardened wear plate, that may be replaceable if worn or broken, or that may include a consumable coating or shoe, or pad. That bearing face of the motion calming, friction damping element may be obtained by treating the surface to yield desired co-efficients of static and dynamic friction whether by application of a surface coating, and insert, a pad, a brake shoe or brake lining, or other treatment. Shoes and linings may be obtained from clutch and brake lining suppliers, of which one is Railway Friction Products. Such a shoe or lining may have a polymer based or composite matrix, loaded with a mixture of metal or other particles of materials to yield a specified friction performance.

That friction surface may, when employed in combination with the opposed bearing surface, have a co-efficient of static friction, :_s, and a co-efficient of dynamic or kinetic friction, :_k. The coefficients may vary with environmental conditions. For the purposes of this description, the friction coefficients will be taken as being considered on a dry day condition at 70 F. In one embodiment, when dry, the coefficients of friction may be in the range of 0.15 to 0.45, may be in the narrower range of 0.20 to 0.35, and, in one embodiment, may be about 0.30. In one embodiment that coating, or pad, may, when employed in combination with the opposed bearing surface of the sideframe column, result in coefficients of static and dynamic friction at the friction interface that are within 20%, or, more narrowly, within 10 % of each other. In another embodiment, the coefficients of static and dynamic friction are substantially equal.

Sloped Wedge Surface

Where damper wedges are employed, a generally low friction, or controlled friction pad or coating may also be employed on the sloped surface of the damper that engages the wear plate (if such is employed) of the bolster pocket where there may be a partially sliding, partially rocking dynamic interaction. The present inventors consider the use of a controlled friction interface between the slope face of the wedge and the inclined face of the bolster pocket, in which the combination of wear plate and friction member may tend to yield coefficients of friction of known properties, to be advantageous. In some embodiments those coefficients may be the same, or nearly the same, and may have little or no tendency to exhibit stick-slip behaviour, or may have a reduced stick-slip tendency as compared to cast iron on steel. Further, the use of brake linings, or inserts of cast materials having known friction properties may tend to permit the properties to be controlled within a narrower, more predictable and more repeatable range such as may yield a reasonable level of consistency in operation. The coating, or pad, or lining, may be a polymeric element, or an element having a polymeric or composite matrix loaded with suitable friction materials. It may be obtained from a brake or clutch lining manufacturer, or the like. One such firm that may be able to provide such friction materials is Railway Friction Products of 13601 Laurinburg Maxton Ai, Maxton NC; another may be Quadrant EPP USA Inc., of 2120 Fairmont Ave., Reading PA. In one embodiment, the material may be the same as that employed by the Standard Car Truck Company in the "Barber Twin Guard" (t.m.) damper wedge with polymer covers. In one embodiment the material may be such that a coating, or pad, may, when employed with the opposed bearing surface of the sideframe column, result in coefficients of static and dynamic friction at the friction interface that are within 20%, or more narrowly, within 10% of each other. In another embodiment, the coefficients of static and dynamic friction are substantially equal. The co-efficient of dynamic friction may be in the range of 0.15 to 0.30, and in one embodiment may be about 0.20.

A damper may be provided with a friction specific treatment, whether by coating, pad or lining, on both the vertical friction face and the slope face. The coefficients of friction on the slope face need not be the same as on the friction face, although they may be. In one embodiment it may be that the coefficients of static and dynamic friction on the friction face may be about 0.3, and may be about equal to each other, while the coefficients of static and dynamic friction on the slope face may be about 0.2, and may be about equal to each other. In either case, whether on the vertical bearing face against the sideframe column, or on the sloped face in the bolster pocket, the present inventors consider it to be advantageous to avoid surface pairings that may tend to lead to galling, and stick-slip behaviour.

Spring Groups

The main spring groups may have a variety of spring layouts. Among various double damper embodiments of spring layout are the following: <tables id="tabl0001" num="0001"><table frame="all"><tgroup cols="9" align="center"><colspec colnum="1" colname="col1" colwidth="18mm" /><colspec colnum="2" colname="col2" colwidth="10mm" colsep="0" /><colspec colnum="3" colname="col3" colwidth="10mm" colsep="0" /><colspec colnum="4" colname="col4" colwidth="10mm" /><colspec colnum="5" colname="col5" colwidth="10mm" colsep="0" /><colspec colnum="6" colname="col6" colwidth="10mm" colsep="0" /><colspec colnum="7" colname="col7" colwidth="10mm" /><colspec colnum="8" colname="col8" colwidth="28mm" /><colspec colnum="9" colname="col9" colwidth="21mm" /><thead><row><entry rowsep="0" valign="top" /><entry rowsep="0" valign="top" /><entry rowsep="0" valign="top" /><entry rowsep="0" valign="top" /><entry rowsep="0" valign="top" /><entry rowsep="0" valign="top">X₁</entry><entry rowsep="0" valign="top" /><entry rowsep="0" valign="top" /><entry rowsep="0" valign="top" /></row><row><entry rowsep="0" valign="top">D₁ X₁ D₃</entry><entry rowsep="0" valign="top">D₁</entry><entry rowsep="0" valign="top"> X₁</entry><entry rowsep="0" valign="top">D₃</entry><entry rowsep="0" valign="top">D₁</entry><entry rowsep="0" valign="top"> X₂</entry><entry rowsep="0" valign="top">D₃</entry><entry rowsep="0" valign="top">D₁ X₁ X₂ X₃ D₃</entry><entry rowsep="0" valign="top">D₁ X₁ X₂ D₃</entry></row><row><entry rowsep="0" valign="top">X₂ X₃ X₄</entry><entry rowsep="0" valign="top">X₂</entry><entry rowsep="0" valign="top" /><entry rowsep="0" valign="top">X₃</entry><entry rowsep="0" valign="top" /><entry rowsep="0" valign="top" /><entry rowsep="0" valign="top" /><entry rowsep="0" valign="top">X₄ X₅ X₆ X₇ X₈</entry><entry rowsep="0" valign="top">D₂ X₃ X₄ D₄</entry></row><row><entry valign="top">D₂ X₅ D₄</entry><entry valign="top">D₂</entry><entry valign="top">X₄</entry><entry valign="top">D₄</entry><entry valign="top">D₂</entry><entry valign="top">X₃</entry><entry valign="top">D₄</entry><entry valign="top">D₂ X₉ X₁₀ X₁₁ D₄</entry><entry valign="top" /></row></thead><tbody><row><entry>3 x 3</entry><entry namest="col2" nameend="col4" align="center">3:2:3</entry><entry namest="col5" nameend="col7" align="center">2:3:2</entry><entry>3 x 5</entry><entry>2 x 4</entry></row></tbody></tgroup></table></tables>

In these groups, D_i represents a damper spring, and X_i represents a non-damper spring.

In the context of 100 Ton or 110 Ton trucks, the inventors propose spring and damper combinations lying within 20 % (and preferably within 10 %) of the following parameter envelopes: <ol id="ol0002" compact="compact"><li>(a) For a four wedge arrangement with all steel or iron damper surfaces, an envelope having an upper boundary according to <b>k_damper</b> = 2.41(<b>θ_wedge</b>)1.76, and a lower boundary according to <b>k_damper</b> = 1.21(<b>θ_wedge</b>)1.76.</li><li>(b) For a four wedge arrangement with all steel or iron damper surfaces, a mid range zone of <b>k_damper</b> = 1.81(<b>θ_wedge</b>)^1.76 (+/- 20 %).</li><li>(c) For a four wedge arrangement with non-metallic damper surfaces, such as may be similar to brake linings, an envelope having an upper boundary according to <b>k_damper</b> = 4.84(<b>θ_wedge</b>)^1.64<b>,</b> and a lower a lower boundary according to <b>k_damper</b> = 2.42(<b>θ_wedge</b>)^1.64 where the wedge angle may lie in the range of 30 to 60 degrees.</li><li>(d) For a four wedge arrangement with non-metallic damper surfaces, a mid range zone of<b>k_damper</b> = 3.63(<b>θ_wedge</b>)^1.64 (+/- 20 %). Where <dl id="dl0002" compact="compact"><dt><b>k_damper</b></dt><dd>is the side spring stiffness under each damper in lbs/in/damper</dd><dt><b>θ_wedge-</b></dt><dd>is the associated primary wedge angle, in degrees</dd></dl></li></ol>

<b>θ_wedge</b> may tend to lie in the range of 30 to 60 degrees. In other embodiments <b>θ_wedge</b> may lie in the range of 35 - 55 degrees, and in still other embodiments may tend to lie in the narrower range of 40 to 50 degrees.

It may be advantageous to have upward and downward damping forces that are not overly dissimilar, and that may in some cases tend to be roughly equal. Frictional forces at the dampers may differ depending on whether the damper is being loaded or unloaded. The angle of the wedge, the coefficients of friction, and the springing under the wedges can be varied. A damper is being "loaded" when the bolster is moving downward in the sideframe window, since the spring force is increasing, and hence the force on the damper is increasing. Similarly, a damper is being "unloaded" when the bolster is moving upward toward the top of the sideframe window, since the force in the springs is decreasing. The equations can be written as: While loading: <maths id="math0005"><math display="block"><msub><mi mathvariant="bold">F</mi><mi mathvariant="normal">d</mi></msub><mo>=</mo><msub><mi mathvariant="bold">μ</mi><mi mathvariant="normal">c</mi></msub><mspace width="1em" /><msub><mi mathvariant="normal">F</mi><mi mathvariant="normal">s</mi></msub><mo>⁢</mo><mfrac><mfenced><mi>Cot</mi><mspace width="1em" /><mrow><mo>(</mo><mi mathvariant="bold">Φ</mi><mo>)</mo><mo>-</mo><msub><mi mathvariant="bold">μ</mi><mi mathvariant="normal">s</mi></msub></mrow></mfenced><mfenced><mn>1</mn><mo>+</mo><mrow><mo>(</mo><msub><mi mathvariant="bold">μ</mi><mi mathvariant="normal">s</mi></msub><mo>-</mo><msub><mi mathvariant="bold">μ</mi><mi mathvariant="normal">c</mi></msub><mo>)</mo><mi>Cot</mi></mrow><mspace width="1em" /><mrow><mo>(</mo><mi mathvariant="bold">Φ</mi><mo>)</mo><mo>+</mo><msub><mi mathvariant="bold">μ</mi><mi mathvariant="normal">s</mi></msub><mspace width="1em" /><msub><mi mathvariant="bold">μ</mi><mi mathvariant="normal">c</mi></msub></mrow></mfenced></mfrac></math><img file="EP1997708A2_D0005.tif" /></maths> While unloading: <b>F_d</b> = <maths id="math0006"><math display="block"><msub><mi mathvariant="bold">μ</mi><mi mathvariant="normal">c</mi></msub><mspace width="1em" /><msub><mi mathvariant="bold">F</mi><mi mathvariant="normal">s</mi></msub><mo>⁢</mo><mfrac><mfenced><mi>Cot</mi><mspace width="1em" /><mrow><mo>(</mo><mi mathvariant="bold">Φ</mi><mo>)</mo><mo>+</mo><msub><mi mathvariant="bold">μ</mi><mi mathvariant="normal">s</mi></msub></mrow></mfenced><mfenced><mn>1</mn><mo>+</mo><mrow><mo>(</mo><msub><mi mathvariant="bold">μ</mi><mi mathvariant="normal">c</mi></msub><mo>-</mo><msub><mi mathvariant="bold">μ</mi><mi mathvariant="normal">s</mi></msub><mo>)</mo><mi>Cot</mi></mrow><mspace width="1em" /><mrow><mo>(</mo><mi mathvariant="bold">Φ</mi><mo>)</mo><mo>+</mo><msub><mi mathvariant="bold">μ</mi><mi mathvariant="normal">s</mi></msub><mspace width="1em" /><msub><mi mathvariant="bold">μ</mi><mi mathvariant="normal">c</mi></msub></mrow></mfenced></mfrac></math><img file="EP1997708A2_D0006.tif" /></maths> Where: <ul id="ul0004" list-style="none" compact="compact"><li><b>F_d</b> = friction force on the sideframe column</li><li><b>F_s</b> = force in the spring</li><li><b>µ_s =</b> coefficient of friction on the angled slope face on the bolster</li><li><b>µ_c =</b> the coefficient of friction against the sideframe column</li><li><b>φ =</b> the included angle between the angled face on the bolster and the friction face bearing against the column</li></ul>

For a given angle, a friction load factor, <b>C_f</b> can be determined as <b>C_f</b> = <b>F_d</b> /<b>F_s</b>. This load factor <b>C_f</b> will tend to be different depending on whether the bolster is moving up or down.

It may be advantageous to have different vertical spring rates in the empty and fully loaded conditions. To that end springs of different heights may be employed, for example, to yield two or more vertical spring rates for the entire spring group. In this way, the dynamic response in the light car condition may be different from the dynamic response in a fully loaded car, where two spring rates are used. Alternatively, if three (or more) spring rates are used, there may be an intermediate dynamic response in a semi-loaded condition. In one embodiment, each spring group may have a first combination of springs that have a free length of at least a first height, and a second group of springs of which each spring has a free length that is less than a second height, the second height being less than the first height by a distance δ₁, such that the first group of springs will have a range of compression between the first and second heights in which the spring rate of the group has a first value, namely the sum of the spring rates of the first group of springs, and a second range in which the spring rate of the group is greater, namely that of the first group plus the spring rate of at least one of the springs whose free height is less than the second height. The different spring rate regimes may yield corresponding different damping regimes.

For example, in one embodiment a car having a dead sprung weight (i.e., the weight of the car body with no lading excluding the unsprung weight below the main spring such as the sideframes and wheelsets), of about 35,000 to about 55,000 lbs (+/- 5000 lbs) may have spring groups of which a first portion of the springs have a free height in excess of a first height. The first height may, for example be in the range of about 9 - ¾ to 10 - ¼ inches. When the car sits, unladen, on its trucks, the springs compress to that first height. When the car is operated in the light car condition, that first portion of springs may tend to determine the dynamic response of the car in the vertical bounce, pitch-and-bounce, and side-to-side rocking, and may influence truck hunting behaviour. The spring rate in that first regime may be of the order of 12,000 to 22,000 lbs/ in., and may be in the range of 15,000 to 20,000 lbs/in.

When the car is more heavily laden, as for example when the combination of dead and live sprung weight exceeds a threshold amount, which may correspond to a per car amount in the range of perhaps 60,000 to 100,000 lbs, (that is, 15,000 to 25,000 lbs per spring group for symmetrical loading, at rest) the springs may compress to, or past, a second height. That second height may be in the range of perhaps 8-½ to 9-¾ inches, for example. At this point, the sprung weight is sufficient to begin to deflect another portion of the springs in the overall spring group, which may be some or all of the remaining springs, and the spring rate constant of the combined group of the now compressed springs in this second regime may tend to be different, and larger than, the spring rate in the first regime. For example, this larger spring rate may be in the range of about 20,000 - 30,000 Ibs/in., and may be intended to provide a dynamic response when the sum of the dead and live loads exceed the regime change threshold amount. This second regime may range from the threshold amount to some greater amount, perhaps tending toward an upper limit, in the case of a 110 Ton truck, of as great as about 130,000 or 135,000 lbs per truck. For a 100 Ton truck this amount may be 115,000 or 120,000 lbs per truck.

Table 1 gives a tabulation of a number of spring groups that may be employed in a 100 or 110 Ton truck, in symmetrical 3 x 3 spring layouts and that include dampers in four-cornered groups. The last entry in Table 1 is a symmetrical 2:3:2 layout of springs. The term "side spring" refers to the spring, or combination of springs, under each of the individually sprung dampers, and the term "main spring" referring to the spring, or combination of springs, of each of the main coil groups: <tables id="tabl0002" num="0002"><table frame="all"><title>Table 1 - Spring Group Combinations</title><tgroup cols="7"><colspec colnum="1" colname="col1" colwidth="23mm" /><colspec colnum="2" colname="col2" colwidth="20mm" /><colspec colnum="3" colname="col3" colwidth="18mm" /><colspec colnum="4" colname="col4" colwidth="18mm" /><colspec colnum="5" colname="col5" colwidth="20mm" /><colspec colnum="6" colname="col6" colwidth="19mm" /><colspec colnum="7" colname="col7" colwidth="20mm" /><thead><row><entry valign="top">Group</entry><entry valign="top">D7-G1</entry><entry valign="top">D7-G2</entry><entry valign="top">D7-G3</entry><entry valign="top">D7-G4</entry><entry valign="top">D7-G5</entry><entry valign="top">D5-G1</entry></row></thead><tbody><row><entry morerows="2" valign="middle">Main Springs</entry><entry>5*D7-O</entry><entry>5*D7-O</entry><entry>5*D7-O</entry><entry>5*D7-O</entry><entry>5*D7-O</entry><entry>5*D5-O</entry></row><row><entry>5 * D6-I</entry><entry>5 * D6-I</entry><entry>5 * D8-I</entry><entry>5 * D8-I</entry><entry>5 * D7-I</entry><entry>5 * D6-I</entry></row><row><entry>5*D6A</entry><entry>5*D6A</entry><entry>5*D8A</entry><entry>5 *D8A</entry><entry>5*D8A</entry><entry align="center">---</entry></row><row><entry morerows="1" valign="middle">Side Springs</entry><entry>4*B353</entry><entry>4*B353</entry><entry>4*NSC-1</entry><entry>4*B353</entry><entry>4 * B353</entry><entry>4*B432</entry></row><row><entry align="center">---</entry><entry>4* B354</entry><entry>4* B354</entry><entry>4* NSC-2</entry><entry>4* NSC-2</entry><entry>4* B433</entry></row><row><entry namest="col1" nameend="col7" align="left" /></row></tbody></tgroup><tgroup cols="7"><colspec colnum="1" colname="col1" colwidth="23mm" /><colspec colnum="2" colname="col2" colwidth="20mm" /><colspec colnum="3" colname="col3" colwidth="18mm" /><colspec colnum="4" colname="col4" colwidth="18mm" /><colspec colnum="5" colname="col5" colwidth="20mm" /><colspec colnum="6" colname="col6" colwidth="19mm" /><colspec colnum="7" colname="col7" colwidth="20mm" /><thead><row><entry valign="top">Group</entry><entry valign="top">D5-G2</entry><entry valign="top">D5-G3</entry><entry valign="top">D5-G4</entry><entry valign="top">D5-G5</entry><entry valign="top">D5-G6</entry><entry valign="top">D5-G7</entry></row></thead><tbody><row><entry morerows="2" valign="middle">Main Springs</entry><entry>5*D5-O</entry><entry>5*D5-O</entry><entry>5*D5-O</entry><entry>5*D5-O</entry><entry>5*D5-O</entry><entry>5* D5-O</entry></row><row><entry>5 * D6-1</entry><entry>5 * D6-1</entry><entry>5 * D8-1</entry><entry>5 * D8-1</entry><entry>5 * D6-1</entry><entry>5 * D6-1</entry></row><row><entry>5* D6A</entry><entry align="center">---</entry><entry>5 * D8A</entry><entry>5 * D6A</entry><entry>5 * D6A</entry><entry align="center">---</entry></row><row><entry morerows="1" valign="middle">Side Springs</entry><entry>4 * B432</entry><entry>4 * B353</entry><entry>4 * B353</entry><entry>4 * B353</entry><entry>4 * B353</entry><entry>4 * B353</entry></row><row><entry>4*B433</entry><entry>4*B354</entry><entry>4*B354</entry><entry>4*B354</entry><entry>4*B354</entry><entry>4*B354</entry></row><row><entry namest="col1" nameend="col7" align="left" /></row></tbody></tgroup><tgroup cols="7"><colspec colnum="1" colname="col1" colwidth="23mm" /><colspec colnum="2" colname="col2" colwidth="20mm" /><colspec colnum="3" colname="col3" colwidth="18mm" /><colspec colnum="4" colname="col4" colwidth="18mm" /><colspec colnum="5" colname="col5" colwidth="20mm" /><colspec colnum="6" colname="col6" colwidth="19mm" /><colspec colnum="7" colname="col7" colwidth="20mm" /><thead><row><entry valign="top">Group</entry><entry valign="top">D5-G8</entry><entry valign="top">D5-G9</entry><entry valign="top">D5-G10</entry><entry valign="top">D5-G11</entry><entry valign="top">D5-G12</entry><entry valign="top">No.3</entry></row></thead><tbody><row><entry morerows="2" valign="middle">Main Springs</entry><entry>5*D5-O</entry><entry>5*D5-O</entry><entry>5* D5-O</entry><entry>5* D5-O</entry><entry>5 * D5-O</entry><entry>3* D51-O</entry></row><row><entry>5*D6-I</entry><entry>5 * D6-I</entry><entry>5*D8-I</entry><entry>5*D8-I</entry><entry>5 * D5-I</entry><entry>3*D61-I</entry></row><row><entry>5* D6B</entry><entry>5*D6A</entry><entry>5* D8A</entry><entry>5*D8A</entry><entry>5*D6B</entry><entry>3*D61A</entry></row><row><entry morerows="1" valign="middle">Side Springs</entry><entry>4*NSC-1</entry><entry>4*NSC-1</entry><entry>4*NSC-1</entry><entry>4*NSC-1</entry><entry>4*B353</entry><entry>4*B353-O</entry></row><row><entry>4 * NSC-2</entry><entry>4 * B354</entry><entry>4 * B354</entry><entry>4 * NSC-2</entry><entry>4 * NSC-2</entry><entry>4 * B354-1</entry></row></tbody></tgroup></table></tables>

In this tabulation, the terms NSC-1, NSC-2, D8, D8A and D6B refer to springs of non-standard size proposed by the present inventors. The properties of these springs are given in Table 2a (main springs) and 2b (side springs), along with the properties of the other springs of Table 1. <tables id="tabl0003" num="0003"><table frame="all"><title>Table 2a Main Spring Parameters</title><tgroup cols="8"><colspec colnum="1" colname="col1" colwidth="23mm" /><colspec colnum="2" colname="col2" colwidth="22mm" /><colspec colnum="3" colname="col3" colwidth="15mm" /><colspec colnum="4" colname="col4" colwidth="22mm" /><colspec colnum="5" colname="col5" colwidth="22mm" /><colspec colnum="6" colname="col6" colwidth="23mm" /><colspec colnum="7" colname="col7" colwidth="18mm" /><colspec colnum="8" colname="col8" colwidth="23mm" /><thead><row><entry morerows="1" valign="top">Main Springs</entry><entry valign="top">Free Height</entry><entry valign="top">Rate</entry><entry valign="top">Solid Height</entry><entry valign="top">Free to Solid</entry><entry valign="top">Solid Capacity</entry><entry valign="top">Diameter</entry><entry valign="top">d - Wire Diameter</entry></row><row><entry valign="top">(in)</entry><entry valign="top">(lbs/in)</entry><entry valign="top">(in)</entry><entry valign="top">(in)</entry><entry valign="top">(lbs)</entry><entry valign="top">(in)</entry><entry valign="top">(in)</entry></row></thead><tbody><row><entry>D5 Outer</entry><entry>10.2500</entry><entry>2241.6</entry><entry align="char" char="." charoff="9">6.5625</entry><entry align="char" char="." charoff="9">3.6875</entry><entry>8266</entry><entry align="char" char="." charoff="10">5.500</entry><entry align="char" char=".">0.9531</entry></row><row><entry>D51 Outer</entry><entry>10.2500</entry><entry>2980.6</entry><entry align="char" char="." charoff="9">6.5625</entry><entry align="char" char="." charoff="9">3.6875</entry><entry>10991</entry><entry align="char" char="." charoff="10">5.500</entry><entry align="char" char=".">1.0000</entry></row><row><entry>D5 Inner</entry><entry>10.3125</entry><entry>1121.6</entry><entry align="char" char="." charoff="9">6.5625</entry><entry align="char" char="." charoff="9">3.7500</entry><entry>4206</entry><entry align="char" char="." charoff="10">3.3750</entry><entry align="char" char=".">0.6250</entry></row><row><entry>D6 Inner</entry><entry>9.9375</entry><entry>1395.2</entry><entry align="char" char="." charoff="9">6.5625</entry><entry align="char" char="." charoff="9">3.3750</entry><entry>4709</entry><entry align="char" char="." charoff="10">3.4375</entry><entry align="char" char=".">0.6563</entry></row><row><entry>D61 Inner</entry><entry>10.1875</entry><entry>1835.9</entry><entry align="char" char="." charoff="9">6.5625</entry><entry align="char" char="." charoff="9">3.6250</entry><entry>6655</entry><entry align="char" char="." charoff="10">3.4375</entry><entry align="char" char=".">0.6875</entry></row><row><entry>D6A Inner Inner</entry><entry>9.0000</entry><entry>463.7</entry><entry align="char" char="." charoff="9">5.6875</entry><entry align="char" char="." charoff="9">3.3125</entry><entry>1536</entry><entry align="char" char="." charoff="10">2.0000</entry><entry align="char" char=".">0.3750</entry></row><row><entry>D61 A Inner Inner</entry><entry>10.0000</entry><entry>823.6</entry><entry align="char" char="." charoff="9">6.5625</entry><entry align="char" char="." charoff="9">3.4375</entry><entry>2831</entry><entry align="char" char="." charoff="10">2.0000</entry><entry align="char" char=".">0.3750</entry></row><row><entry>D7 Outer</entry><entry>10.8125</entry><entry>2033.6</entry><entry align="char" char="." charoff="9">6.5625</entry><entry align="char" char="." charoff="9">4.2500</entry><entry>8643</entry><entry align="char" char="." charoff="10">5.5000</entry><entry align="char" char=".">0.9375</entry></row><row><entry>D7 Inner</entry><entry>10.7500</entry><entry>980.8</entry><entry align="char" char="." charoff="9">6.5625</entry><entry align="char" char="." charoff="9">4.1875</entry><entry>4107</entry><entry align="char" char="." charoff="10">3.5000</entry><entry align="char" char=".">0.6250</entry></row><row><entry>D6B Inner Inner</entry><entry>9.7500</entry><entry>575.0</entry><entry align="char" char="." charoff="9">6.5625</entry><entry align="char" char="." charoff="9">3.1875</entry><entry>1833</entry><entry align="char" char="." charoff="10">2.0000</entry><entry align="char" char=".">0.3940</entry></row><row><entry>D8 Inner</entry><entry>9.5500</entry><entry>1395.0</entry><entry align="char" char="." charoff="9">6.5625</entry><entry align="char" char="." charoff="9">2.9875</entry><entry>4168</entry><entry align="char" char="." charoff="10">3.4375</entry><entry align="char" char=".">0.6563</entry></row><row><entry>D8 Inner Inner</entry><entry>9.2000</entry><entry>575.0</entry><entry align="char" char="." charoff="9">6.5625</entry><entry align="char" char="." charoff="9">2.6375</entry><entry>1517</entry><entry align="char" char="." charoff="10">2.0000</entry><entry align="char" char=".">0.3940</entry></row></tbody></tgroup></table></tables><tables id="tabl0004" num="0004"><table frame="all"><title>Table 2b - Side Spring Parameters</title><tgroup cols="8"><colspec colnum="1" colname="col1" colwidth="20mm" /><colspec colnum="2" colname="col2" colwidth="20mm" /><colspec colnum="3" colname="col3" colwidth="15mm" /><colspec colnum="4" colname="col4" colwidth="21mm" /><colspec colnum="5" colname="col5" colwidth="22mm" /><colspec colnum="6" colname="col6" colwidth="23mm" /><colspec colnum="7" colname="col7" colwidth="24mm" /><colspec colnum="8" colname="col8" colwidth="24mm" /><thead><row><entry morerows="1" valign="top">Side Springs</entry><entry valign="top">Free Height</entry><entry valign="top">Rate</entry><entry valign="top">Solid Height</entry><entry valign="top">Free to Solid</entry><entry valign="top">Solid Capacity</entry><entry valign="top">Coil Diameter</entry><entry valign="top">d - Wire Diameter</entry></row><row><entry valign="top">(in)</entry><entry valign="top">(lbs/in)</entry><entry valign="top">(in)</entry><entry valign="top">(in)</entry><entry valign="top">(lbs)</entry><entry valign="top">(in)</entry><entry valign="top">(in)</entry></row></thead><tbody><row><entry>B353 Outer</entry><entry>11.1875</entry><entry>1358.4</entry><entry align="char" char=".">6.5625</entry><entry>4.6250</entry><entry>6283</entry><entry align="char" char="." charoff="8">4.8750</entry><entry align="char" char=".">0.8125</entry></row><row><entry>B354 Inner</entry><entry>11.5000</entry><entry>577.6</entry><entry align="char" char=".">6.5625</entry><entry>49375</entry><entry>2852</entry><entry align="char" char="." charoff="8">3.1250</entry><entry align="char" char=".">0.5313</entry></row><row><entry>B355 Outer</entry><entry>10.7500</entry><entry>1358.8</entry><entry align="char" char=".">6.5625</entry><entry>4.1875</entry><entry>5690</entry><entry align="char" char="." charoff="8">4.8750</entry><entry align="char" char=".">0.8125</entry></row><row><entry>B356 Inner</entry><entry>10.2500</entry><entry>913.4</entry><entry align="char" char=".">6.5625</entry><entry>3.6875</entry><entry>3368</entry><entry align="char" char="." charoff="8">3.1250</entry><entry align="char" char=".">0.5625</entry></row><row><entry>B432 Outer</entry><entry>11.0625</entry><entry>1030.4</entry><entry align="char" char=".">6.5625</entry><entry>4.5000</entry><entry>4637</entry><entry align="char" char="." charoff="8">3.8750</entry><entry align="char" char=".">0.6719</entry></row><row><entry>B433Inner</entry><entry>11.3750</entry><entry>459.2</entry><entry align="char" char=".">6.5625</entry><entry>4.8125</entry><entry>2210</entry><entry align="char" char="." charoff="8">2.4063</entry><entry align="char" char=".">0.4375</entry></row><row><entry>49427-1 Outer</entry><entry>11.3125</entry><entry>1359.0</entry><entry align="char" char=".">6.5625</entry><entry>4.7500</entry><entry>6455</entry><entry align="char" char="." charoff="8" /><entry align="char" char="." /></row><row><entry>49427-2 Inner</entry><entry>10.8125</entry><entry>805.0</entry><entry align="char" char=".">6.5625</entry><entry>4.2500</entry><entry>3421</entry><entry align="char" char="." charoff="8" /><entry align="char" char="." /></row><row><entry>B358 Outer</entry><entry>10.7500</entry><entry>1546.0</entry><entry align="char" char=".">6.5625</entry><entry>4.1875</entry><entry>6474</entry><entry align="char" char="." charoff="8">5.0000</entry><entry align="char" char=".">0.8438</entry></row><row><entry>B359 Inner</entry><entry>11.3750</entry><entry>537.5</entry><entry align="char" char=".">6.5625</entry><entry>4.8125</entry><entry>2587</entry><entry align="char" char="." charoff="8">3.1875</entry><entry align="char" char=".">0.5313</entry></row><row><entry>52310-1 Outer</entry><entry>11.3125</entry><entry>855.0</entry><entry align="char" char=".">6.5625</entry><entry>4.7500</entry><entry>4061</entry><entry align="char" char="." charoff="8" /><entry align="char" char="." /></row><row><entry>52310-2 Inner</entry><entry>8.7500</entry><entry>2444.0</entry><entry align="char" char=".">6.5625</entry><entry>2.1875</entry><entry>5346</entry><entry align="char" char="." charoff="8" /><entry align="char" char="." /></row><row><entry>11-1-0562 Outer</entry><entry>12.5625</entry><entry>997.0</entry><entry align="char" char=".">6.5625</entry><entry>6.0000</entry><entry>5982</entry><entry align="char" char="." charoff="8" /><entry align="char" char="." /></row><row><entry>11-1-0563 Outer</entry><entry>12.6875</entry><entry>480.0</entry><entry align="char" char=".">6.5625</entry><entry>6.1250</entry><entry>2940</entry><entry align="char" char="." charoff="8" /><entry align="char" char="." /></row><row><entry>NSC-1 Outer</entry><entry>11.1875</entry><entry>952.0</entry><entry align="char" char=".">6.5625</entry><entry>4.6250</entry><entry>4403</entry><entry align="char" char="." charoff="8">4.8750</entry><entry align="char" char=".">0.7650</entry></row><row><entry>NSC-2 Inner</entry><entry>11.5000</entry><entry>300.0</entry><entry align="char" char=".">6.5625</entry><entry>4.9375</entry><entry>1481</entry><entry align="char" char="." charoff="8">3.0350</entry><entry align="char" char=".">0.4580</entry></row></tbody></tgroup></table></tables>

Table 3 provides a listing of truck parameters for a number of known trucks, and for trucks proposed by the present inventors. In the first instance, the truck embodiment identified as No. 1 may be taken to employ damper wedges in a four-cornered arrangement in which the primary wedge angle is 45 degrees (+/-) and the damper wedges have steel bearing surfaces. In the second instance, the truck embodiment identified as No. 2, may be taken to employ damper wedges in a four-cornered arrangement in which the primary wedge angle is 40 degrees (+/-), and the damper wedges have non-metallic bearing surfaces. <tables id="tabl0005" num="0005"><table frame="all"><title>Table 3 - Truck Parameters</title><tgroup cols="9"><colspec colnum="1" colname="col1" colwidth="19mm" /><colspec colnum="2" colname="col2" colwidth="20mm" /><colspec colnum="3" colname="col3" colwidth="18mm" /><colspec colnum="4" colname="col4" colwidth="19mm" /><colspec colnum="5" colname="col5" colwidth="22mm" /><colspec colnum="6" colname="col6" colwidth="19mm" /><colspec colnum="7" colname="col7" colwidth="18mm" /><colspec colnum="8" colname="col8" colwidth="17mm" /><colspec colnum="9" colname="col9" colwidth="19mm" /><thead><row><entry valign="top" /><entry valign="top">NACO Swing Motion</entry><entry valign="top">Barber S-2-E</entry><entry valign="top">Barber S-2-HD</entry><entry valign="top">ASF Super Service RideMaster</entry><entry valign="top">ASF Motion Control</entry><entry valign="top">No.1</entry><entry valign="top">No. 2</entry><entry valign="top">No. 3 2:3:2</entry></row></thead><tbody><row><entry morerows="2">Main Springs</entry><entry>6* D7-O</entry><entry>7*D5-0</entry><entry>6*D5-0</entry><entry>7*D5-O</entry><entry>7*D5-O</entry><entry>5*D5-O</entry><entry>5*D5-O</entry><entry>3*D51-0</entry></row><row><entry>7*D7-1</entry><entry>7*DS-I</entry><entry>7*D6-I</entry><entry>7*DS-I</entry><entry>5*DS-I</entry><entry>5*D8-1</entry><entry>5*D6-I</entry><entry>3*D61-I</entry></row><row><entry>4 * D6A</entry>&lt;entry /&gt;<entry>4* D6A</entry><entry>2 * D6A</entry>&lt;entry /&gt;<entry>5 * D8A</entry><entry>5 * D6A</entry><entry>3*D61-A</entry></row><row><entry morerows="1">Side Springs</entry><entry>2*49427-1</entry><entry>2*B353</entry><entry>2*B353</entry><entry>2*5062</entry><entry>2*5062</entry><entry>2*NSC-1</entry><entry>4*B353</entry><entry>4*B353</entry></row><row><entry>2*49427-2</entry><entry>2*B354</entry><entry>2*B354</entry><entry>2* 5063</entry><entry>2* 5063</entry><entry>2* B354</entry><entry>4* B354</entry><entry>4* B354</entry></row><row><entry>k_empty</entry><entry>22414</entry><entry>27414</entry><entry>27088</entry><entry>26496</entry><entry>24253</entry><entry>17326</entry><entry>18952</entry><entry>22194</entry></row><row><entry>k_loaded</entry><entry>25197</entry><entry>27414</entry><entry>28943</entry><entry>27423</entry><entry>24253</entry><entry>27177</entry><entry>28247</entry><entry>24664</entry></row><row><entry>Solid</entry><entry>103,034</entry><entry>105,572</entry><entry>105,347</entry><entry>107,408</entry><entry>96,735</entry><entry>98,773</entry><entry>107,063</entry><entry>97,970</entry></row><row><entry>H_Empty</entry><entry>10.3504</entry><entry>9.9898</entry><entry>9.8558</entry><entry>10.0925</entry><entry>10.0721</entry><entry>9.9523</entry><entry>10.0583</entry><entry>10.0707</entry></row><row><entry>H_Loaded</entry><entry>7.9886</entry><entry>7.9562</entry><entry>7.8748</entry><entry>8.0226</entry><entry>7.7734</entry><entry>7.7181</entry><entry>7.9679</entry><entry>7.8033</entry></row><row><entry>k_w</entry><entry>4328</entry><entry>3872</entry><entry>3872</entry><entry>2954</entry><entry>2954</entry><entry>6118</entry><entry>7744</entry><entry>7744</entry></row><row><entry>k_w/k_loaded</entry><entry>17.18</entry><entry>14.12</entry><entry>13.38</entry><entry>10.77</entry><entry>12.18</entry><entry>22.51</entry><entry>27.42</entry><entry>31.40</entry></row><row><entry>Wedge α</entry><entry>45</entry><entry>32</entry><entry>32</entry><entry>37.5</entry><entry>37.5</entry><entry>45</entry><entry>40</entry><entry>45</entry></row><row><entry>F_D (down)</entry><entry>1549</entry><entry>3291</entry><entry>3291</entry><entry>1711</entry><entry>1711</entry><entry>2392</entry><entry>2455</entry><entry>2522</entry></row><row><entry>F_D (up)</entry><entry>1515</entry><entry>1742</entry><entry>1742</entry><entry>1202</entry><entry>1202</entry><entry>2080</entry><entry>2741</entry><entry>2079</entry></row><row><entry>Total F_D</entry><entry>3064</entry><entry>5033</entry><entry>5033</entry><entry>2913</entry><entry>2913</entry><entry>4472</entry><entry>5196</entry><entry>4601</entry></row></tbody></tgroup></table></tables>

In Table 3, the Main Spring entry has the format of the quantity of springs, followed by the type of spring. For example, the ASF Super Service Ride Master, in one embodiment, has 7 springs of the D5 Outer type, 7 springs of the D5 Inner type, nested inside the D5 Outers, and 2 springs of the D6A Inner-Inner type, nested within the D5 Inners of the middle row (i.e, the row along the bolster centerline). It also has 2 side springs of the 5052 Outer type, and 2 springs of the 5063 Inner type nested inside the 5062 Outers. The side springs would be the middle elements of the side rows underneath centrally mounted damper wedges.

<b>k</b>_empty refers to the overall spring rate of the group in lbs/in for a light (i.e., empty) car.

<b>k</b>_loaded refers to the spring rate of the group in lbs/in., in the fully laded condition.

"Solid" refers to the limit, in lbs, when the springs are compressed to the solid condition

<b>H</b>_Empty refers to the height of the springs in the light car condition

<b>H</b>_Loaded refers to the height of the springs in the at rest fully loaded condition

<b>k</b>_w refers to the overall spring rate of the springs under the dampers.

<b>k</b>_w/<b>k</b>_loaded gives the ratio of the spring rate of the springs under the dampers to the total spring rate of the group, in the loaded condition, as a percentage.

The wedge angle is the primary angle of the wedge, expressed in degrees.

F_D is the friction force on the sideframe column. It is given in the upward and downward directions, with the last row giving the total when the upward and downward amounts are added together.

In various embodiments of trucks, such as truck 22, the resilient interface between each sideframe and the end of the truck bolster associated therewith may include a four cornered damper arrangement and a 3 x 3 spring group having one of the spring groupings set forth in Table 1. Those groupings may have wedges having primary angles lying in the range of 30 to 60 degrees, or more narrowly in the range of 35 to 55 degrees, more narrowly still in the range 40 to 50 degrees, or may be chosen from the set of angles of 32, 36, 40 or 45 degrees. The wedges may have steel surfaces, or may have friction modified surfaces, such as non-metallic surfaces.

The combination of wedges and side springs may be such as to give a spring rate under the side springs that is 20 % or more of the total spring rate of the spring groups. It may be in the range of 20 to 30 % of the total spring rate. In some embodiments the combination of wedges and side springs may be such as to give a total friction force for the dampers in the group, for a fully laden car, when the bolster is moving downward, that is less than 3000 lbs. In other embodiments the arithmetic sum of the upward and downward friction forces of the dampers in the group is less than 5500 lbs.

In some embodiments in which steel faced dampers are used, the sum of the magnitudes of the upward and downward friction forces may be in the range of 4000 to 5000 lbs. In some embodiments, the magnitude of the friction force when the bolster is moving upward may be in the range of 2/3 to 3/2 of the magnitude of the friction force when the bolster is moving downward. In some embodiments, the ratio of Fd(Up)/Fd (Down) may lie in the range of 3/4 to 5/4. In some embodiments the ratio of Fd(Up)/Fd(Down) may lie in the range of 4/5 to 6/5, and in some embodiments the magnitudes may be substantially equal.

In some embodiments in which non-metallic friction surfaces are used, the sum of the magnitudes of the upward and downward friction force may be in the range of 4000 to 5500 lbs. In some embodiments, the magnitude of the friction force when the bolster is moving up, Fd(Up), to the magnitude of the friction force when the bolster is moving down, Fd(Down) may be in the range of 3/4 to 5/4, may be in the range of 0.85 to 1.15. Further, those wedges may employ a secondary angle, and the secondary angle may be in the range of about 5 to 15 degrees.

Nos. 1 and 2

The inventors consider the combinations of parameters listed in Table 3 under the columns No. 1 and No. 2, to be advantageous. No. 1 may employ with steel on steel damper wedges and sideframe columns. No. 2 may employ non-metallic friction surfaces, that may tend not to exhibit stick-slip behaviour, for which the resultant static and dynamic friction coefficients are substantially equal. The friction coefficients of the friction face on the sideframe column may be about 0.3. The slope surfaces of the wedges may also work on a non-metallic bearing surface and may also tend not to exhibit stick slip behaviour. The coefficients of static and dynamic friction on the slope face may also be substantially equal, and may be about 0.2. Those wedges may have a secondary angle, and that secondary angle may be about 10 degrees.

No. 3

In some embodiments there may be a 2:3:2 spring group layout. In this layout the damper springs may be located in a four cornered arrangement in which each pair of damper springs is not separated by an intermediate main spring coil, and may sit side-by-side, whether the dampers are cheek-to-cheek or separated by a partition or intervening block. There may be three main spring coils, arranged on the longitudinal centreline of the bolster. The springs may be non-standard springs, and may include outer, inner, and inner-inner springs identified respectively as D51-O, D61-I, and D61-A in Tables 1,2 and 3 above. The No. 3 layout may include wedges that have a steel-on-steel friction interface in which the kinematic friction co-efficient on the vertical face may be in the range of 0.30 to 0.40, and may be about 0.38, and the kinematic friction co-efficient on the slope face may be in the range of 0.12 to 0.20, and may be about 0.15. The wedge angle may be in the range of 45 to 60 degrees, and may be about 50 to 55 degrees. In the event that 50 (+/-) degree wedges are chosen, the upward and downward friction forces may be about equal (i.e., within about 10 % of the mean), and may have a sum in the range of about 4600 to about 4800 lbs, which sum may be about 4700 lbs (+/- 50). In the event that 55 degree (+/-) wedges are chosen, the upward and downward friction forces may again be substantially equal (within 10 % of the mean), and may have a sum on the range of 3700 to 4100 Lbs, which sum may be about 3850 - 3900 lbs.

Alternatively, in other embodiments employing a 2:3:2 spring layout, non-metallic wedges may be employed. Those wedges may have a vertical face to sideframe column co-efficient of kinematic friction in the range of 0.25 to 0.35, and which may be about 0.30. The slope face co-efficient of kinematic friction may be in the range of 0.08 to 0.15, and may be about 0.10. A wedge angle of between about 35 and about 50 degrees may be employed. It may be that the wedge angles lie in the range of about 40 to about 45 degrees. In one embodiment in which the wedge angle is about 40 degrees, the upward and downward kinematic friction forces may have magnitudes that are each within about 20 % of their average value, and whose sum may lie in the range of about 5400 to about 5800 lbs, and which may be about 5600 lbs (+/-100). In another embodiment in which the wedge angle is about 45 degrees, the magnitudes of each of the upward and downward forces of kinematic friction may be within 20 % of their averaged value, and whose sum may lie in the range of about 440 to about 4800 lbs, and may be about 4600 lbs (+/- 100).

Combinations and Permutations

The present description recites many examples of dampers and bearing adapter arrangements. Not all of the features need be present at one time, and various optional combinations can be made. As such, the features of the embodiments of several of the various figures may be mixed and matched, without departing from the spirit or scope of the invention. For the purpose of avoiding redundant description, it will be understood that the various damper configurations can be used with spring groups of a 2 X 4, 3 X 3, 3:2:3, 2:3:2, 3 X 5 or other arrangement. Similarly, several variations of bearing to pedestal seat adapter interface arrangements have been described and illustrated. There are a large number of possible combinations and permutations of damper arrangements and bearing adapter arrangements. In that light, it may be understood that the various features can be combined, without further multiplication of drawings and description.

The various embodiments described herein may employ self-steering apparatus in combination with dampers that may tend to exhibit little or no stick-slip. They may employ a "Pennsy" pad, or other elastomeric pad arrangement, for providing self-steering. Alternatively, they may employ a bi-directional rocking apparatus, which may include a rocker having a bearing surface formed on a compound curve of which several examples have been illustrated and described herein. Further still, the various embodiments described herein may employ a four cornered damper wedge arrangement, which may include bearing surfaces of a non-stick-slip nature, in combination with a self steering apparatus, and in particular a bi-directional rocking self-steering apparatus, such as a compound curved rocker.

In the various embodiments of trucks herein, the gibs may be shown mounted to the bolster inboard and outboard of the wear plates on the side frame columns. In the embodiments shown herein, the clearance between the gibs and the side plates is desirably sufficient to permit a motion allowance of at least ¾" of lateral travel of the truck bolster relative to the wheels to either side of neutral, advantageously permits greater than 1 inch of travel to either side of neutral, and may permit travel in the range of about 1 or 1-1/8" to about 1 - 5/8 or 1 - 9/16" inches to either side of neutral.

The inventors presently favour embodiments having a combination of a bi-directional compound curvature rocker surface, a four cornered damper arrangement in which the dampers are provided with friction linings that may tend to exhibit little or no stick-slip behaviour, and may have a slope face with a relatively low friction bearing surface. However, there are many possible combinations and permutations of the features of the examples shown herein. In general it is thought that a self draining geometry may be preferable over one in which a hollow is formed and for which a drain hole may be required.

In each of the trucks shown and described herein, the overall ride quality may depend on the interrelation of the spring group layout and physical properties, or the damper layout and properties, or both, in combination with the dynamic properties of the bearing adapter to pedestal seat interface assembly. It may be advantageous for the lateral stiffness of the sideframe acting as a pendulum to be less than the lateral stiffness of the spring group in shear. In rail road cars having 110 ton trucks, one embodiment may employ trucks having vertical spring group stiffnesses in the range of 16,000 lbs/inch to 36,000 lbs/inch in combination with an embodiment of bi-directional bearing adapter to pedestal seat interface assemblies as shown and described herein. In another embodiment, the vertical stiffness of the spring group may be less than 12,000 Ibs./in per spring group, with a horizontal shear stiffness of less than 6000 Ibs./in.

The double damper arrangements shown above can also be varied to include any of the four types of damper installation indicated at page 715 in the <i>1997 Car and Locomotive Cyclopedia,</i> whose information is incorporated herein by reference, with appropriate structural changes for doubled dampers, with each damper being sprung on an individual spring. That is, while inclined surface bolster pockets and inclined wedges seated on the main springs have been shown and described, the friction blocks could be in a horizontal, spring biased installation in a pocket in the bolster itself, and seated on independent springs rather than the main springs. Alternatively, it is possible to mount friction wedges in the sideframes, in either an upward orientation or a downward orientation.

The embodiments of trucks shown and described herein may vary in their suitability for different types of service. Truck performance can vary significantly based on the loading expected, the wheelbase, spring stiffnesses, spring layout, pendulum geometry, damper layout and damper geometry.

Various embodiments of the invention have been described in detail. Since changes in and or additions to the above-described best mode may be made without departing from the nature, spirit or scope of the invention, the invention is not to be limited to those details but only by the appended claims.