Untitled record

Application filed May 8,1903. Serial No. 156,217. (No model.)

To all whom it .may concern:

Be it known that I, Ernest Nickerson, a citizen of the United States, and a resident of Newton, in the county of Middlesex and State 5 of Massachusetts, have invented a new and useful Improvement in Cranes, of which the following is a full, clear, and exact description, reference being had to the accompanying drawings, forming a part of this specification, io in explaining its nature.

The invention relates to an improvement in cranes and to that kind of crane where an automatically-moved counterbalancing-weight is provided to offset the weight of the load or 15 object lifted.

The invention consists in an improved means whereby the movement of the counterbalancing-weight may be automatically obtained by utilizing the power of the thrust caused by 20 the load acting through the boom by which it is supported and developed at its seat or point of jointure to the fixed part of the crane.

The invention further consists in means whereby the crane provided with such coun2 5 terbalance may be protected against the strain arising from, its extreme weight in case the object to be lifted should suddenly become detached from the crane by the breaking of a chain or line or other intermediary support, 30 especially when the strain of- the load is first put upon the crane, and which strain of the counterbalance unless provided against would be equally as disastrous upon the crane as the weight of the load would have been without 35 the counteracting influence of the counterbalance, and even more so, owing to the sudden shock.

Figure 1 shows, my improved crane structure in elevation.: . Fig: 2 shows in plan a de4° tail thereof, to which reference will hereinafter be made. Fig. 3 shows in horizontal section a detail of my construction, to which reference will hereinafter be made. Fig. 4 shows the improved crane in' plan looking down upon 45 the same. Fig. 5 shows in elevation the structure and correlation of the braces, to which reference will hereinafter be made.' Fig. 6 is a longitudinal vertical section upon the line 6 6 of Fig. 7. Fig. 7 shows in plan a modi50 fied portion of the structure, to which refer ence will hereinafter be made. Fig. 8 is a view of one of the concave steps shown at d in Fig. 1. Fig. 9 is a cross - sectional detail view taken at the top of the adjustable braces.

Referring to the drawings, A represents the 55 main body of the crane supported so as to be rotatable upon a suitable turn-table A'. By reason of the adaptability of the improved crane being used as a locomotive-crane, the turn-table A' is shown fixed to a movable 60 truck A⁸. Rising from the main body of the crane is the mast a. a! represents the jib or boom extension. For sustaining the boom, raising or lowering it, or for changing its inclination there is shown the chain or line /, 65 having suitable sheave or pulley attachments, and which chain or line is controlled in any suitable manner. / represents the hoisting rope or chain. This rope or chain has the usual sheave a pulley attachments, by which 70 its. lifting stress can best be utilized. The hoisting rope or chain connects with a drum or windlass turned by hand or power. These elements just referred to are common to all cranes and require no further reference or explana- 75 tion.

Extending from the main body of the crane is the overhang A³, which carries the coun- . terbalancing-weight A⁴. The overhang comprises girders suitably braced and at the back 80 end of which stays / are secured, which connect with the top of the mast a. Along the bottom of the overhang the flanges / are extended, upon which is laid the track /, extending on an upward incline from the main 85 body of the crane. Running on this track and supported by suitable wheels or trucks is the counterbalance A⁴, which must be of suflicient weight to counterbalance the load to be lifted when run out to some relative position upon 90 the track /. The normal position of the counterbalancing-weight A⁴, by reason of the inclination of the track upon which it runs, would be. close in against the main body of the crane or in a position approximately over 95 the base of its support, where it would cause the least strain when there was no load upon the crane. For moving the counterbalance along the track to a position where it will as nearly as possible balance that of the load to 100

752,248 be lifted there is utilized the force of the thrust caused by the load acting through the boom by which it is supported. In other words, the relation of the boom to the load is 5 such that the weight of the load causes a thrust of variable intensity, dependent upon the weight of the load and the inclination of the boom, to be developed in the boom at its seat or point of jointure with the fixed body of the i o crane, and which thrust is utilized and used as a source of power by making the end of the boom movable, then through suitable means of transmission applying it to the counterbalance to move it to its correct position or where it will as 15 nearly as possible offset the weight of the load.

Various expedients may be resorted to for transmitting the power so obtained to the counterbalance either by application through hydraulic or pneumatic pressures or by appli2o cation through mechanical means, as gears, levers, and the like, or the application of the thrust to the setting of valves or other methods of control acting upon forces generated for the purpose of moving the counterbalance 25 to its correct position, all of which means would be within the essence of my invention looked at in its broader significance. As illustrative further of such transmittory means and as tending to the reduction of the inven30 tion to a working basis there is provided, a means whereby hydraulic pressure is the instrument for transmitting the power of the thrust. The means may be effected as follows: There is formed in the fixed body of the crane a chamber B, the back end and floor or base of which are made solid with a stability sufficient to withstand any strain subjected by the lower inner end of the boom, which rests within this chamber, as its seat or base of support.

For the purpose of utility, as will hereinafter appear, the lower end of the boom contained within the chamber B is made cleft with feet b' b', which take the form of flanged castings, to which the cleft ends of the boom are piv45 otally or otherwise secured. These castings or feet are supported against a lateral displacement or working by side guides V V'. They carry rollers b³ b³ upon their bottom sides, the axes of which rollers are at right 50 angles with the central line of the boom. The rollers rest to move with a limited degree of movement upon the floor or base of the chamber B or any other table of support formed thereon wherefore the sliding horizontal 55 movement or thrust to the end of the boom is obtained.

Within the chamber B, and preferably formed between the cleft ends of the boom, are the cylinder-chambers δ⁴ δ⁴ δ⁴, the headed ends 60 of which butt against the inner wall of the said chamber. There are three of the cylinder-chambers shown; but this number is arbitrarily taken. Each cylinder-chamber has its piston δ⁶, which pistons are simultaneously 65 driven by the movable thrust end of the boom.

This result is obtained through the medium of what may be termed the “equalizer-bar” δ°. The rods of the several pistons are secured to this bar,, so that with the movement of the bar their simultaneous movement is obtained 70 and the equalizer-bar is actuated by the thrust end of the boom, to which it is secured at either end by eyebolts or links b\ connecting with the cleft ends of the boom, and preferably by the same fastenings by which the same is secured 75 to their respective feet b' b'. Of course with this order of arrangement it is necessary that the equalizer-bar be actuated by the boom to move with a true even movement, in order that there may be no torsional strain or cramping 80 of the piston within their respective bearings. For obtaining such movement the simple mechanical expedient is resorted to of fixing the beam δ⁸ or other stiffener-bar in the front of the body of the crane in the same plane as the 85 equalizer-bar and in a position to define its true parallel line of motion. Interposed between the stiffener-bar and the equalizer-bar is the guide-bar δ⁹, connected to both bars by links or toggles δ¹⁰, and which guide-bar through the re- 90 straining action of the toggles equalizes the strain and causes the equalizer-bar to always move parallel with the stiffener-bar in the front of the crane or in a true line of movement, and so to simultaneously and uniformly actuate 95 the pistons within their cylinder-chambers. The cylinder-chambers are filled with any incompressible fluid. Connecting with the chambers are the passages δ¹¹, whereby the liquid pressure within the chambers may be- 100 come equalized. Within the wall of the middle chamber is a vent δ¹², connecting with which is the pipe δ¹³, leading to a secondary cylinderchamber C. The chamber C is formed in the front of the main body of the crane. It is 105 made cylindrical in shape and is left open at its rear end leading toward the counterbalancing-weight and from which end when projected extends what may be termed a “telescopic” hydraulic ram c, which is contained no within this chamber. The hydraulic ram c consists of a number of telescoping tubes, the forward end of which when the ram is in outward extension, is left closed. The forward end of each tube is flanged, and the placement 115 of the flanges or the length of the tubes is so graduated that when the tubes are retracted into the chamber C the back edges of the tubes will all lie in the same plane. The telescopic ram of course is used for pressing 120 the counterbalancing-weight A⁴ back along its inclined trackway and for holding it in a position where it will serve to counterbalance the weight to be lifted, as before explained.

The ram accordingly is placed so as to con- 125 tact with the rear end of the counterbalancingweight and to extend in the same line of direction that the weight is moving, so that the contact of the ram against the rear end of the

I counterbalancing-weight is maintained at all 13°

752,248 points of its extension. The ram is guided in its telescopic extension by means of a series of concave steps c', which are built along the bottom of the overhang and which are so 5 made that each step will guide and serve as a stop for a corresponding sectional tube of the ram, which, together with the fact that the cylinders or tubes comprising the ram are so proportioned that it will be extended io to press forward the counterbalance to a point where it will as nearly as possible balance the load to be lifted, can better be understood by explaining the mode of operation governing the parts previously referred to. In the 15 first instance the weight of the object raised causes the lower end of the boom to move or rather be thrust backward. The rolling feet, the horizontal basal support, and guides all facilitate this movement and confine it to a 20 straight line parallel with the center line of the crane. The toggles and connecting-bars also guide the movement and tend to equalize •it. The equalizer-bar transfers the movement to the pistons, whereby they are pressed 25 forward uniformly in their respective cylinder-chambers. Thus the horizontal component of the boom thrust is conveyed to the liquid behind the pistons in their respective cylinders. This liquid, which may be water, 3° oil, or any suitable fluid, will then be forced from all the chambers by reason of their connecting-passages through the pipe connection to. the secondary cylinder-chamber, where it will act upon the piston formed by the rear 35 encl of all the sections to the telescopic ram, which is contained within this secondary cylinder - chamber, as before explained, and will push them backward, carrying with them the counterweight until the largest section 40 or part reaches the end of its corresponding concave step or guide and stops. If then • the pressure on the rear ends of the remaining sections is sufficient to overcome the resistance of the weight of the counterbalance 45 acting along the incline on which it runs, the remaining sections will move forward until the next size cylinder is stopped by the end of its concave step or guide, and so on. When, the total pressure on the remaining free sec5° tions equalizes the force necessary to move the weight of the counterbalance on its incline, the movement finally stops. The cylinders must be so proportioned that, this stoppage will occur when the weight, of the counter55 balance as nearly as possible balances the weight of the load to be lifted. When the load is lifted, it will be noted that the movement of the boom-foot allows the boom to lower slightly. Thus the load will not be 60 raised from the ground until the counterbalance is extended to a position where it will balance the weight of the load. In lowering the weight a reverse operation to that justde^ tailed for the primary action of the cylinders 65 will take place. The weight of the counter3 balance acting along its inclined track will shut back the telescoping sections of the ram into the secondary cylinder-chamber in which they are contained. Simultaneously with the closing back of the telescoping sections the 70 fluid which, each section contains will be forced back into the secondary chamber and thence.into the primary cylinder-chambers, where it will drive back the pistons, which through the intermediary of the equalizer-bar 75 connecting-links will carry back the end of the boom where it will be in a position to be actuated by the weight of the next load.

It will be understood, of course, as before referred to, that the normal position of the 80 counterbalance is at the bottom of its inclined trackway, so that it will consequently press back the telescoping sections of the ram until they are all contained within the secondary cylinder-chamber and in a position to be acted 8 5 upon by the influence of the next fluid charge.

As tending to the further perfection of the crane, which has a counterbalancing-weight, there is shown in Figs. 1 and 5 a means tending to guard the crane against the strain of 90 the weight of the counterbalance in case the chain or other means adapted to attach the object to be lifted, or even the hoisting-line itself, should break when the load is first to be upon it. Of course when the counterbal- 95 ance is moved out on the overhang, away from the. base thereof, should the line break and the weight of the counterbalance be so suddenly deprived of the balancing effect of the load that it is unable to move in toward the base 100 rapidly enough to avoid an overturning action then its strain upon the crane would be equally as disastrous as the weight of the ' load would be without the counteracting influence of the counterbalance, and even more 105 so,, owing to the sudden shock. Accordingly there are .fixed at the end of the overhang, and preferably at either corner thereof, what may be termed “adjustable braces” connecting with the ground or any other fixed base of no support. The adjustable braces are made alike. Each comprises a case d, fixed to the overhang and braced to hang in a vertical position.'..Each, case d is tapped on its inside bore with a female thread. Fitting into the 115 threaded bore of the case is the hollow screw d, which is also threaded on its inside to receive the screw iZ², which threads on the interior of said screw for receiving the screw d? run in a direction so reverse to the threads on 120 the outside of said screw, which fit into the case tf, that the two screws d! d? are moved up or down by turning them in reverse directions, this for purposes as will hereinafter appear.

The.screws d! are braced against else than a 125 vertical movement by sets of braces extending . m opposite directions—by the fixed braces d, which extend back and at their upper ends are secured to the under side of the overhang and at their lower ends to the attaching members 130

752,248 those of the screw / and which are prevented from turning by the bar dP, will advance with reference to the screw /, thus having the combined advance of the threads of both screws / / and lowering the lower ends of the braces 7° rapidly. When fully extended, the space, if any exists, between, the lower end of each brace and the ground or blocking will be taken up by the screws /, which are to be turned by hand. With such means of support for the 75 back end of the overhang the danger of the crane becoming strained by the overbalancing-weight in case the load becomes accidentally detached by the breaking of a line or otherwise is entirely eliminated. When the 80 load is lifted and it is seen the fastenings will bear the weight of the load, if it is then wished to move the crane, with its load, or.swing it on its center, the reverse motion is imparted to the screws and they will be run up. This 85 feature of my invention has been treated from the standpoint that two braces are used to furnish the back support for the overhang. Tw0 braces are better, because they furnish a more stable support; but of course one might be 90 used without departing in any way from the spirit of my invention.

Reference has already been made to the fact that in so far as the essence of my invention is concerned various means may be employed 95 to be acted upon by the movable end of the boom, whereby its power and motion may be ^;transmitted to move the counterbalancingweight to its correct position or where it will as nearlv as possible offset the weight of the load. 10c In modification, therefore, of the hydraulic means of transmission before referred to I have shown in Figs. 6 and 7 a system of gearing . adapted to be acted upon by the movable boom end and act as the means of transmission. The 10; mechanical combination of its elements and mode of operation is as follows: e represents · one or more racks secured to the equalizer-bar / and extending backward therefrom in line with the motion of the boom-foot, and which n· racks through the medium of the equalizer-bar are adapted to have the same relative degree of motion as the foot of the boom, the equalizerbar being secured thereto, as before explained. The racks have any suitable roller-support e' 11 and are made to engage with pinions e, the motion of which, through suitable gears <? e , is conveyed to the driving-drum / upon the same shaft with the gear /, around which a rope or chain P is wound. One end of the 12 line P is attached to. the forward end of the counterbalancing-weight, while the other end is passed down around the pulley e , fixed below the drum, thence is extended back and around the pulley e\ and is then extended and 12 secured to the rear end of the counterbalancing-weight. It is obvious that by properly graduating the relative size of the gears the counterbalancing-weight will be moved out upon its trackway a distance corresponding 13

-A d\ which are suitably bored and threaded to fit each its. screw, and by the sets of braces /, which connect with the adjacent screws d' across the back end of the overhang. The braces./ connect with each one of the screws d' at two points in order to secure an added stability of structure and also so that the braces may'move simultaneously with the screws and_:securely hold the same whatever their posii o tion may be. Such connection is made by the members / /. The upper of said members / is bored so as to fit over the thread of the screws above the threaded members /, while the members / of the braces are secured to the lower end of the respective screws d' by fitting each in a circular groove /, formed therein, in which the members or, rather, screws turn freely. The members / d¹ therefore ad- . vance and retract with the screws, carrying

2o with them the whole system of braces /, wherefore the screws are braced whatever • their position may be. The screws /, which fit into the screws /, as before explained, are held against turning by a connecting-rod /, rigidly secured to their lower ends. The screws d: are hollow, and they are threaded on their insides to receive the screw d\ the ends of which are fitted to rest against the ground or other fixed base of support. The system of screws comprising the separate braces, with the exception of the screws /, are turned by smooth square shafts /°, rigidly attached to the tops of the screws / and inside their respective casings d, and each of which shafts pass through a bushing dP in the bevel-gear /², by which the shaft is turned with a sliding fit. The bushing aforesaid is formed to project from the respective gears /², and the outside of the part projecting from the gear is turned around and bears on the sides of a circular hole dP in the top of its corresponding case / which thus forms a journal for it. Each bevel-gear dP intermeshes with a complemental gear /⁴, which gears /⁴ are turned by shafts dP, rotated by the engine of the crane or any suitable way. The simultaneous action of the adjustable set of screws comprising each of the separate braces will be as follows: Assuming the hoisting-line of the crane 50 is about to be attached to the object to be lifted, the screws will then be substantially in the position shown in Fig. 1. The screws / will be turned up to within their respective cases, and the shafts by which they are turned will 55 be extended up through the square hole in the bushing, through which they slide, as before explained. The screws / will be wholly or partially contained within the screws /. The screws P will accordingly be removed from the ground or other base of support. The operator then, through the intermediary of the shafts dP, the bevel-gears /² /⁴, and the shafts /°, will turn the screws / to advance forward. At the same time the screws /, whose exterior 65 threads are laid in the opposite direction to

752,248 with the distance the boom-foot is moved, or rather a distance relatively commensurate with the weight of the load, so having the efiX°^^C01iⁿi^er^^a^a^ilciⁿg it- Upon the release 5 of the load the counterbalancing-weight would gravitate back along its inclined track and by reason of the method of line connection would draw the parts back into place or to their normal posture in readiness to be influenced ¹⁰ by the next load, whatever its size or weight ^may be. It is to be noted that the track upon which the counterbalancing-weight is borne is gradually more sharply inclined as it extends from the base. This is for the purpose 15 ot compensating, through the increase of pressure that would be necessary to move the counter balancing-weight, for the increase of pressure developed by the weight of the load as the boom-foot is thrust back, the boom 20 then extending gradually ata lesser degree of angle and exerting gradually a more direct pressure than when in its normal position before being moved. It is obvious that the mechanical expedient could be resorted to of se25 curing the rack or racks to the boom end and directly actuating the pinions and other means of transmission; but I would prefer to actuate the members through the medium of the equalizer-bar, that can be guided in its mbve3° ment, as before explained. This latter means just referred to for receiving the power and motion of the boom-foot is but illustrative of various changes that may be made in my invention without departing from its essential 35 character, and while I have described mechanism which I consider at this time to be best adapted for the purposes of the invention I do not wish to be understood as limiting myself to the specific constructions that I have shown 4° and described.