Railcar bogie bearing adapter construction

0001The present invention relates to a bearing adapter assembly for a railcar bogie. More specifically, tightly secured bearing adapters firmly hold the axle bearing in position to avoid angling and lateral axle variation, and the resultant bogie "warping". Past research has illustrated railcar bogie warping induces bogie hunting during railcar travel, which warping causes undue wear on rails and wheels as well as increasing fuel usage.

0002In a three-piece railcar bogie assembly, the side frames and bolster are generally square, that is the axles and bolster are approximately parallel to each other, and the side frames are parallel to each other but normal to the axles and bolster. After bogie assembly and at certain railcar speeds, the bogie may become dynamically unstable, which may be loosely defined as bogie hunting. Bogie hunting is defined in the Car and Locomotive Cyclopedia (1974) as "an instability at high speed of a wheel set (bogie) , causing it to weave down the track, usually with the (wheel) flanges striking the rail." Bogie hunting has been the subject of many past and ongoing research efforts within the rail industry by bogie suppliers, car builders and railroad lines, as this condition is undesirable from both operational and safety considerations. Past research efforts have noted a significant relationship between bogie warping and resultant bogie hunting. These research efforts and some of their conclusions are discussed in the ASME paper, "Bogie Hunting in the Three-Piece Freight Car Bogie" by V. T. Hawthorne, which paper included historical reference to still earlier research in this field. One of the earlier researchers noted "...that in the empty car the higher column force of the constant column damping provides a greater warp stiffness and, consequently, yields a higher critical (bogie) hunting speed." The ASME paper described a project that was designed to measure the following parameters: warp stiffness; lateral damping force; and, lateral spring rate.

0003The warp stiffness results in this Hawthorne project duplicated earlier test results and it was noted that as the warp angle increased to 1°(60 minutes) of angular displacement, the warp stiffness dropped off appreciably. Further, it was noted that earlier warp stiffness data showed that 1° of displacement represented the maximum warp travel of a relatively new bogie during hunting. Therefore, at warp angles prevalent in bogie hunting, the warp stiffness fell considerably below the values necessary to raise the critical speed of hunting above the normal operating range of the freight railcar.

0004A field test noted that a new railcar bogie running at a speed above 60 miles per hour with track inputs causing warp angles below 0.3° would not be expected to hunt. However, if the warp angle suddenly became 1.0° due to a track irregularity, it is expected that the critical bogie hunting speed of the railcar would drop to about 52 miles per hour and intermittent bogie hunting would occur.

0005A three-piece railcar bogie generally allows a considerable amount of relative movement between the wheel and axle assembly, or the wheelset which includes the axle, wheels and the bearings, and the supporting side frame at the side-frame pedestal jaw. This may be due to manufacturing tolerances permitted in the various components, that is the side-frame pedestal jaw and bearing adapter, and to the form of the connection for the bearing adapter, the journal end of the wheelset and the integral jaws of the side frame structure. U.S. Patent No. 3,211,112 to Baker discloses an assembly to damp the relative lateral movement between the wheel and axle assembly, and the associated side frame. More specifically, a resilient means or member is provided between the top of the journal end of the wheel and axle assembly, and the associated side frame member to produce varying frictional forces for damping the relative movement between the assembly and the side frame. The Baker-'112 patent recognized the undesirability of transmitting track perturbations through the wheelset, side frames and bolsters, but inhibition of this force transmission is intended to be accomplished by damping the disturbances caused by the lateral axle movements, not by suppressing their initiation.

0006In U.S. Patent No. 3,274,955 to Thomas and also in U.S. Patent No. 3,276,395 to Heintzel, a roller bearing adapter is illustrated with an elastomer on the upper part of the cap plate, which adapter is positioned in the side frame pedestal jaw with the elastomer between the pedestal roof and the adapter for relieving exposure to high stresses. A similar concept is shown in U.S. Patent No. 3,381,629 to Jones, which provided an elastomeric material between each bearing assembly and the pedestal roof to accommodate axial movements of the bearing assemblies of each axle and to alleviate lateral impact to the side frame.

0007Other means have been utilized for maintaining a bogie in a square or parallel relationship. In U.S. Patent No. 4,103,623-Radwill, friction shoes are provided to frictionally engage both the side frame column and bolster. This friction shoe arrangement is intended to increase the restraining moment, which is expected to result in an increased bogie hunting speed. The friction shoes had contact surfaces with some appropriate manufacturing tolerance to control initial contact areas to develop a maximum restraining moment.

0008U.S. Patent No. 4,192,240 to Korpics provided a wear liner against the roof of a side-frame pedestal jaw. The disclosure recognized the detrimental effects of having a loose wear liner in the pedestal jaw. Wear liners are provided against the roof of the pedestal jaw to reduce wear in the roof caused by oscillating motions of the side frame relative to the wheel-axle assembly and the bearing. The disclosed wear liner included upwardly projecting tabs to grip the roof and side frame to inhibit longitudinal movement of the wear liner, and downwardly projecting legs to cooperate with the pedestal-jaw stop lugs to inhibit lateral movement of the wear liner relative to the roof. The stop lugs of the pedestal jaw are positioned on opposite sides of the depending legs of the jaw, which lugs are engageable with the downwardly depending wear liner legs.

0009U.S. Patent No. 3,621,792 to Lisch provides a pedestal jaw opening with outwardly sloped sidewalls and a bearing adapter with sloped sidewalls positioned in the jaw opening. An elastomeric is positioned between the adapter and the pedestal sidewall and roof, which elastomer provides resistance in compression and yieldability in shear, and sufficient softness for cushioning. It is noted that by positioning the elastomeric pad between all the interfaces of the adapter and the pedestal jaw, metal-to-metal contact is prevented along with wear and transmission of noise and vibration from the track to thebogie framing. Similarly in U.S. Patent Nos. 3,699,897 and 4,416,203 to Sherrick, a resilient pad is provided between the bearing adapter and the side frame.

0010In U.S. Patent No. 4,072,112 to Wiebe, an elastomeric positioning means is placed intermediate the bearing carrier and one of the pedestal jaws to bias the bearing carrier into direct communication or engagement with the opposite pedestal jaw to limit relative angular movement and linear displacement of the wheel set to the side frame.

0011U.S. Patent No. 4,108,080 and 4,030,424 to Garner et al. teach a rigid H-frame bogie assembly having resilient journal pads in the pedestal jaws. The bogie provided by this development demonstrated improved riding characteristics. Similarly U.S. Patent Nos. 4,082,043 and 4,103,624 to Hammonds et al. disclose an integral H-frame bogie with resilient elements in the journal bearings.

0012In U.S. Patent No. 4,242,966 to Holt et al., a railcar bogie has a transom with a pair of tubes rigidly connected between the longitudinally extending side frames. The transom allows vertical movement of the side frames but resists longitudinal displacement of the side frames with respect to each other.

0013U.S. Patent No. 4,841,875 to Corsten et al. provides a suspension arrangement with at least two annular elastomeric shock absorbers having an optimum adjustability in the longitudinal and transverse directions of the vehicle.

0014Alternative means for the insertion and securing of a wear liner against a pedestal jaw roof are taught in U.S. Patent Nos. 4,034,681 and 4,078,501 to Neumann et al. and 4,192,240 to Korpics, which patents have a common assignee. The objective of these patent disclosures was to provide improved means for securing a wear liner in the jaw to minimize its movement and to improve the assembly means. The wear liners are provided with downwardly depending legs and stop lugs positioned to inhibit movement of the wear liner, such as in the lateral direction relative to the roof.

0015U.S. Patent No. 4,428,303 to Tack illustrates a clip-on pedestal wear plate especially adapted for worn pedestal surfaces. A pair of wear plates, or a single member with a central portion of the plate removed, may be used to provide the structure of the invention.

0016All of the above disclosed apparatus disclose a journal assembly or an assembly for a railcar bogie axle end, which assembly is operable in the pedestal jaw, and the disclosures recognized the desirability of keeping the bogie side frames aligned with each other to avoid bogie hunting. However, the several disclosures provided a plurality of resilient means or structures in the pedestal jaw and around the axle journal bearings, but none of the structures addressed the problem of maintaining the bearing adapter and consequently the axle and side frames in their aligned positions. Several of the above-noted references specifically utilized elastomeric or resilient components in the pedestal jaw or in association with the journal bearing to accommodate the disturbances and flexing motions experienced by the axles and side frames.

0017Side frames for a railcar bogie have pedestals at both of its longitudinal ends with jaws to receive the journal ends of the axle shafts. These journal ends are generally provided with wheel bearings, which are mounted and secured in bearing adapters positioned in the pedestal jaws with the intent that the axles, usually two, of the bogie remain aligned and parallel during railcar travel. The above-noted bearing adapters are generally secured in the pedestal jaw by means such as interlocking surfaces and frequently are provided with wear plates positioned between the adapter and the pedestal jaw roof to minimize wear from the repeated flexing of the adapter in the jaw during railcar travel.

0018The present invention provides an integrally cast bearing adapter in the roof of the pedestal jaw, which adapter is cast with the side frame and pedestal jaw and thereafter may be precision machined or otherwise finished. This secondary finishing accommodates the journal bearing on the axle end, avoids the build up of manufacturing tolerances from the assembly of a multiplicity of parts, and minimizes the flexural displacement in the jaw and bearing to more narrowly limit the lateral displacement of the axle and side frame assemblies to reduce railcar bogie warping and consequent bogie hunting. This integral jaw and bearing assembly reduces the lateral angular displacement below 1°, and in a preferred embodiment the displacement is less than 0.35°. It is recognized that bogie hunting is not eliminated per se, but at the reduced angling and angles of lateral displacement, and thus reduced frequency of vibration, the critical speed, where bogie hunting becomes a negative operating factor, is increased beyond the normal operating speed of the railcar.

0019In another embodiment, the cast-in-place adapter includes vertically extending arms, which have been machined to accept the journal bearing outer race. At assembly of the axle and bearing end into the adapter and pedestal jaw the inner walls of the downwardly depending legs of the bearing adapter accept the outer race and contact the outer surface of the race at, or below, the horizontal cross-sectional diameter of the axle. Contact of the inner walls of the cast-in-place bearing adapter provide a secure retention of the axle and bearing assembly to further inhibit and constrain lateral and rotational movement of the journal bearing outer race within the pedestal jaw, especially in the horizontal plane, thus avoiding warping and bogie hunting.

BRIEF DESCRIPTION OF THE DRAWINGS

0020An embodiment of the invention will now be described by way of example only and with reference to the accompanying drawings.

0021In the drawings, like reference numerals identify like components and in the drawings: <ul id="ul0001" list-style="none" compact="compact"><li>Figure 1 is a side elevation view of a side frame and pedestal jaw with the as-cast and machined bearing adapter highlighted with sectional lines;</li><li>Figure 2 is a side elevation view of an exemplary prior art side-frame pedestal jaw with the wear plate, bearing adapter and axle end positioned therein;</li><li>Figure 3 is a cross-sectional viewof the pedestal jaw, wear plate and bearing adapter of Figure 2 with an axle and journal bearing positioned therein;</li><li>Figure 4 is a cross-sectional view of the pedestal jaw and machined bearing adapter of the present invention with the axle and journal bearing positioned therein;</li><li>Figure 5 is an exploded view of an exemplary prior art pedestal jaw, wear liner, bearing adapter and journal bearing assembly;</li><li>Figure 6 is a oblique view of a railcar bogie;</li><li>Figure 7 is a side elevation of a side frame and pedestal jaw with the as-cast and machined bearing adapter of the separate embodiment having the extended depending legs highlighted with sectional lines; and,</li><li>Figure 8 is a side elevational view of the as-cast bearing adapter and pedestal jaw of Figure 7 with an axle and bearing assembly nested and secured therein.</li></ul>

0022A railcar bogie 10 as illustrated in Figure 6 is generally an assembly of three main components, that is a first side frame 12, a second side frame 14 and a bolster 16 extending therebetween at about the midpoints of parallel side frames 12 and 14, which bolster 16 is about normal to each of side frames 12 and 14. Each of side frames 12 and 14 are about parallel to longitudinal axis 18 and include first end 20 and second end 22, which ends 20,22 each include a pedestal jaw 24 with a bearing opening 26. As each of the pedestal jaws 24 and bearing openings 26 are similar only one will be described, but the description will be applicable to each of openings 26 and jaws 24 of side frames 12 and 14.

0023In bogie 10, first and second axles 28 and 30, which have wheels 32, 34, 36 and 38 positioned on their respective first axle-end 29 and second axle-end 31, are mounted at the respective first and second ends 20 and 22 of side frames 12 and 14, and extend therebetween about normal to longitudinal axis 18. The various ancillary elements of the bogie, such as the spring pack and friction shoes, are not noted but typically are a part of a bogie assembly 10.

0024In Figures 2, 3 and 5 enlarged and exploded views of an end of axle shaft 28 note a relatively common type of structure. In Figure 2, axle shaft end 29 extends through pedestal jaw 24 and opening 26. Wear liner 42 is nested against roof 44 of jaw 24 and, journal bearing and bearing sleeve 46 are an annular bearing assembly, which is slidingly mounted on shaft end 29. Bearing adapter 48 is secured against wear liner 42 between thrust lugs 52 and 54 of jaw 24, which lugs 52, 54 extend into opening 26. Adapter 48 has arcuate surface 50 and is secured in opening 26 between lugs 52 and 54, and against wear liner 42. Journal bearing assembly 46 fits against arcuate surface 50 and is retained in jaw 24 and opening 26.

0025Indicative of the clearances provided in the assembly of axle end 29, pedestal jaw 24 and opening 26 is the separation 'x' in Figure 2 between outer surface 56 of journal bearing 46 and the inner wall 58 of opening 26. This clearance is required both for the initial manufacturing process tolerances for the various parts of the assembly and for the purpose of providing adequate clearance for assembly of these parts.

0026The assembly of Figure 2 is shown in a longitudinal cross-section in Figure 3 with roof 44 of pedestal jaw 24 grasped by clips 43 of wear liner 42. Similarly in Figure 5, the exploded view of axle end 29, journal bearing 46, bearing adapter 48 and wear liner 42 illustrates the plurality of parts in present axle and side frame assemblies. Accumulation of tolerances and clearances from these parts and their assembly provide gap distances in the final structure, which can lead to the amplification or increase in flexing between the axle and side frames during operation of bogie 10 and consequently to the introduction of bogie hunting.

0027In Figures 1 and 4, the present invention demonstrates the improved structure which leads to the elimination of both independent bearing adapter 48 and wear liner 42, and to a reduction in the lateral angular displacement between axles 28 and 30 and side frames 12 and 14. In Figure 1, a segment of side frame 12 has pedestal jaw 24 with inner pedestal leg 25, outer pedestal leg 27 and bearing adapter 60 outlined in a cross-hatched portion. However, bearing adapter portion 60 is an integral part of the side frame, but it is illustrated in outline form to note its position within pedestal jaw 24 and its relationship to opening 26. In this configuration, bearing adapter 60, which is the functional equivalent of adapter 48 in Figure 2, is initially cast into side frame 12 and pedestal jaw 24. After casting, adapter 60 is machined or ground to provide the proper finish and arcuate contour at pedestal roof 44, which contoured arc 62 is similar to arc surface 50 of bearing adapter 48.

0028As illustrated in Figure 4, journal bearing assembly 46 is securely mated against contoured arc 62 thereby avoiding the build-up of tolerances for each of wear liner 42 and bearing adapter 48. Thus, integrally cast adapter 60 has removed the availability of the manufacturing and assembly specification tolerances of wear liner 42 and bearing adapter 48 for reducing the ability of pedestal jaw 24 and opening 26 to retain and secure the axle 28 relatively tightly against angular displacement, which may lead to a reduction in bogie hunting. First outwardly extending flange 45 extends outward from outboard surface 21 of side frame 12 and second outwardly extending flange 47 extends outwardly along axle 28 from inboard surface 23 of side frame 12. Each of flanges 45 and 47 are downwardly curved from roof 62 and are operable to maintain bearing assembly 46 on axle end 29 in its lateral position in side frame 12. Flanges 45 and 47 are integrally cast with bearing adapter 60.

0029In Figure 7, pedestal jaw 24 has bearing adapter 80 with arc contoured roof 62, inner depending leg 84 and outer depending leg 86. Bearing adapter 80 is an integral cast-in-place part of side frame 12 and pedestal jaw 24, but it is illustrated in outline form to clearly note its position and relationship to pedestal jaw 24 and opening 26. As shown in Figure 7, legs 84 and 86 extend from and are clearly formed with roof section 62 to form adapter 80 with inner contoured wall 88. The effect on adapter 80, and its assembly with axle 29 and bearing 46, of incorporation of extended depending legs to adpater 80 is noted in Figure 8.

0030In the illustration of Figure 8, axle end 29 of either axle 28 or 30 has horizontal cross-section diameter 90, which extends to first contact point 92 and second contact point 94 at surface 56 of bearing 46. In this configuration, depending legs 84 and 86, respectively, contact points 92 and 94 to firmly grasp axle end 29 and bearing 46 in opening 26. Further, in this illustration inner wall 88 conforms to the arcuate shape of axle end 29 and bearing 46 to securely nest these components in opening 26. As shown, the separation distance 'x' between outer surface 56 and inner wall 58 in Figure 2 is eliminated or reduced to a negligible or tolerance value only necessary to permit assembly of the components. In this manner, securely grasping the assembly of axle end 29 and bearing 46 permits retention and constraint of this assembly within opening 26. Retention of assembly 29,46 in opening 26 further reduces lateral motion of assembly 29,46 and more specifically depending legs 84 and 86 extend below horizontal diameter 90 to constrain the assembly against horizontal displacement even in the event of a vertical displacement of such assembly, which vertical displacement would separate bearing outer surface 56 from contact with roof 62. However, as known in the art and shown in Figure 8, a side frame key 95 is utilized to limit the amount of vertical displacement of axle end 29 in opening 26. Key 95 is secured to side frame 12 by locking bolt 97 in proximity to inner depending leg 84 in this figure and is only noted as an exemplary illustration of such known keys.

0031The magnitude of improvement of the angular displacement of axle 28 has been demonstrated by reduction of displacement from about 1° to less than 0.50° during testing. As noted above in earlier research work, decreasing the angular displacement results in improved bogie hunting, or more accurately has been noted to increase the critical speed where bogie hunting commences. Therefore, the improvement attributable to this greater or tighter retention of bearing assembly 46, and thus axle 28, is readily apparent, as this avoids bogie warping or parallelogramming which reduces bogie hunting. Firmer retention of bearing assembly 46 and axle 28 at the side frame cooperates with the improved degree of freedom offered with the modern snubbers or friction shoes (not shown) and bolster 16 assemblies to provide the rigidity and stability to bogie assemblies 10 to avoid bogie warping without the added structural members from supplemental apparatus, such as steering arms. If it is considered necessary to provide better wear characteristics on surface 62 of jaw 24, arcuate surface 62 may be hardened or coated by means known in the art, such as plasma spraying or plating.

0032While only a specific embodiment of the invention has been described and shown, it is apparent to those skilled in the art that various alternatives and modifications can be made thereto. It is, therefore, the intention in the appended claims to cover all such modifications and alternatives as may fall within the true scope of the invention.