US2097133A - Drop table - Google Patents

Description

Oct. 226, 1937. 1 RICHARDSON DROP TABLE Filed Jan. 4, 1935 4 Sheets-Sheet l NVENTOR.

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ATTORNEYS Oct. 26, 1937. I R|CHARDSQN 2,097,133

DROP TABLE Filed Jan. 4, 1955 4 sheets-Sheena a o o ia yf Oei. 26, 1937. L, RlCHARDSON 2,097,133

DROP TABLE Filed Jan. 4, 1935 4 Sheets-Sheet 4 Patented Get. 26, 1937 STATES PATENT orig 11 Claims.

This invention relates to equipment for lowering and raising relatively heavy loads` such, for example, as are encountered in the removal of the wheels of a locomotive and, inasmuch as the in- Vention has been developed with locomotive requirements in view, the embodiment disclosed herein is particularly useful in unwheeling locomotives.

The particular objects and advantages of the invention will probably be better understood if brief reference is first made to the practices of the art as it exists today. For example, the most familiar form of equipment for removing the wheels of a locomotive is probably the one which is known as the hydraulic drop pit. With this apparatus the vehicle is first jacked up in order to remove its weight from the wheels, after which a hydraulic plunger is brought up under the center of the axle of the pair of wheels which is to be removed. The axle is then raised slightly so as to permit lateral removal of the sections of the rail upon which the whe-els had been resting. After the rails are withdrawn, the plunger is dropped in order to lower the axle and its wheels.

The disadvantages of the foregoing equipment are rather numerous. In the first place, the hydraulic mechanism is not susceptible to accurate control nor is the device satisfactory from a safety standpoint for the reason that the axle with its wheels is merely balanced on the top of the plunger and frequently slides off. This is especially likely to occur during the operation of returning the wheels to their position under the locomotive because, if they do not happen to be accurately centered on the plunger, one end orthe other may catch upon some portion of thev mechanism and cause the axle to tip and slide off. Besides the danger involved in injuring the equipment, many serious accidents to workmen have resulted from just such an occurrence.

Another objection to the hydraulic pit is the fact that the pit must be twice as deep as the drop for the plunger, which, of course, increases the cost and difculty of installation. Furthermore, in hydraulic mechanisms more or less leakage is always present which makes the pits sloppy and wet and greatly adds to the hazard.

Another type of device which is very well known to the art at the present time is one which involves the use of a table mounted on four screws, one at each corner and, while tables of this kind have been arranged to carry that portion of the entire weight of the vehicle which is borne by the wheels to be removed so as toavoid the necessity of jacking up the locomotive, yet thisr feature has introduced a serious disadvantage in that the power demanded of the prime mover varies extensively, namely, from that degree of power which is necessary to support the full load of the axle down to that which is necessary to i support merely the axle with its wheels. Furthermore, tables of this kind when in their full lowered position have an appreciable height or thickness, that is, the distance from the rail to the bottom of the pit is` relatively great.

With the foregoing in mind, the objects of m invention will be better understood, the principal ones being as follows:

1. The provision of a greatly simplified drop table equipment and one which is more economical to manufacture, install and maintain;

2. The provision of a drop table which in collapsed or lowered position will have a much reduced vertical dimension;

3. The provision of equipment of the character L described in which the power demandsy upon the prime mover are maintained as nearly constant as possible so as to avoid the necessity for using an extremely powerful motor;

4. The provision of a drop table the operation of which is less hazardous than tables heretofore in use, as well as one which is immediately locked in position should the power fail for any reason;

5. The provision of equipment of the screw type in which the screw is well protected so as to avoid all damage thereto during operation of the device;

6. The provision of a table having pivoted legs, together with means for swinging the legs on their pivots in order to raise or lower the table; and

7. The provision of equipment of the character described in which is employed a combinatio-n of lever or toggle-actuating mechanisms in combination with cam surfaces which cooperate to greatly reduce the variation in power demanded from the prime mover.

How the foregoing objects, together with such other objects as may appear hereinafter or are incident to my invention, are obtained is illustrated in the accompanying drawings which disclose a preferred embodiment of the invention particularly suitable for use in unwheeling locomotives as above mentioned.

In the drawings:

Figure 1 is a side elevation of my improved drop table equipment.

Figure 2 is a plan view.

Figure 3 is an end elevation from the righthand end of. Figures 1 and 2, showing the device g in position in a pit, with the pit, the guides at the sides, and the tracks in the bottom shown in section. f

Figure 4 is a plan View of one of the tracks in the bottom of the pit, showing the arrangement of cams which I employ.

Figure 5 is a diagrammatic View on a reduced scale showing the parts in raised, partly lowered, and fully lowered position in the pit, the pit being shown in vertical-longitudinal section; and

Figure 6 is a graph illustrating the character of the operation secured with my improved device.

Inspection of the drawings will show that the top of the table is constructed as a supporting framework comprising essentially the parallel sections of rail 1, which run transversely of the table, and the longitudinally extending H-beams 8, the rails being suitably recessed topass-the H-beams 8, and the parts being welded together when assembled. The ends of the rails 1 are cut back, as shown at 9 in Figure 3, -in order to leave the lower projecting portions I0 which extend into channel-shaped guides lII which are suitably secured to the upper portions of the side walls of the pit I2. The guides are slightly flared at the bottom, as at I3, and they slope upwardly and inwardly, as best shown in Figure 3, in order to accurately guide the ends of the rails to their proper position when the table is raised from its lowered position to its extreme up-ward position. In this upward'position, the extensions I0 on the rails 1 t under complementary extensions I4 on the adjacent rail sections 1a, which latter, of course, are part of the permanent track associated with the drop table mechanism.

The upper framework of the table just described is supported upon four legs I5 which are pivoted under the ends of the rail section 1 by means of the rail chairs I6. There is one chair YI6 for each leg I5, and the top of each leg is bifurcated in order to straddle the downwardly projecting tongue I1 of the chair, Vthe parts being held together by means of pivot pins I8.

The two legs I5 at the left-hand end of theV table, as viewed in Figures 1 and 2, are bracedtogether near the bottom by means of any suitable interconnecting member I9, and those at the right by means of the interconnecting member 29, the parts being secured together in any desired or suitable manner. Longitudinally of the table, the legs at each side are connected together and, therefore, constrained to move in unison by means of the channels 2l pivoted to the legs at the points 22 and 23.

The two legs at the right in Figures l and 2 are equipped at the bottom on the inside with rollers 24 mounted upon the cross-shaft 25, while the two legs at the left are equipped on the outside with rollers 26Y mounted upon the cross-shaft 21.

The rollers are held in place by Cotter pins 28. The rollers travel over angle-shaped trackways 29 which are provided with the camY surfaces 39, the function of which will appear more fully hereinafter. It should be noted, however, that there is one cam 30 for each leg I5 and that the cams for the right-hand legs are located to the inside of the trackways and those for the left-hand legs to the outside of the trackways', so that the cams for th-e left-hand legs, which are at the outside of the rollers, will not interfere with the rollers 24 on the right-hand legs, which rollers 24 are located on the inside of the trackways 29. In other words, each leg with its'roller is intended Vto roll over one cam only and not over two successive cams. I

It will be clear from the description thus far given that the table top or frame for supporting the load, composed primarily of the rail sections 1 and the H-bearns 8,`may be raised or lowered by swinging the legs I5 on their pivots I3. I will now describe that portion of the mechanism which is provided for so swinging the legs.

As will be seen upon inspection of Figures 1 and 2, the H-beams` 8 project laterally beyond the left-hand rail 1, and upon suitable brackets 3l which span the distance between the beams 3, I mount a power means such as the reversible electric motor 32 which is adapted to drive the operating screw 33. The motor shaft 34 is connected to the screw 33 by means of the sleeve '35 whichis splined to the shaft 34 by the key 35 and non-rotatably connected to the screw 33 by the pin 31. The sleeve 35 is provided with the annular shoulder 38 which lies between two bronze bearing' rings 39. The shoulder 38 and the rings 39 are embraced in a cup-shaped housing 49 which is carried in any suitable manner by the bottom of the rail 1. After assembly, the open end of the housing 40 is closed by means of the thrust bearing plate 4I which is held in place by the bolts 42.

The free end of the screw 33 is threaded into the central block 43 in the operating cross beam 44 which is arranged to slide longitudinally of the tableupon the guides 45 which are attached to the under side of the beams 8. The ends of the beam 44 are bifurcated as at 4B (see Figure l)y in order to embrace the shafts of the turnbuckles 41 which are secured between the bifurcations by means of the pins 48. It will be understood, of course, that the cross arm 44 may be moved one way or the other by means of the screw 33, the arm moving along the screw as it rotates. In Figures 1 and 2, the arm 44 is shown at its extreme right-hand position, in which position the legs I5 are upright and the table is in its raised position. The legs are moved by means of the operating cross bar 44 through the mechanism now to be described.

At the left-hand end of the beams 8 are provided two crank devices in the form of sectorshaped sheaves 49 having xed thereto the crank arms 50. These sheaves are mounted upon the projecting ends of a pivot rod 5I which extends between the beams 8. The ends of the cranks are articulated upon pins 52 to the ends of connecting rods 53, the other ends of which connecting rods are pivoted upon the pins 22 to the legs I5. The sheaves 49 are free to rotate on the pivot rod 5I, and it will be seen that movement in a counter-clockwise direction will raise the cranks50 and pull on the rods 53 in order to swing the legs I5 to the left on their pivots IB and thereby lower the table.

The sheaves are rotated in unison by means ofthe operating cable 54 which serves to insure uniform movement of all of the parts including parallel operation of the bar 44 by virtue of the fact that this cable'is continuously reeved between the ends of the bar 44 and around the sheaves 49 from one side to the other of the table in a manner similar to Vthat which is employed in the operation of a parallel ruler for a drawing board.

To be more specific, the cable is connectedin the following manner. Beginning, for example, with the turn-buckle 41 at the upper side of Figure 2, the cable extends to theright around the lower sheave 55 which is held at a slight angle by means of the supporting bracket 55 so that in rounding the sheavethe cable will leadV to the up-per sheave 51 on the other side of the table, from whence it extends to the inner'groove of the double-groovecl sheave 58 and then downwardly and around the inner groove of the crank sheave 49 on the lower side of the table, as viewed in Figure 2; The cable then comes upI and around the sheave 49 and passes through an opening 59 in this sheave and through they guide ring 60 to the top of the outside groove in the sheave` 49, and from this point it extends downwardly and under the outside groove in the sheave 58, and then back to the turn-buckle 41 on the lower side of the beam 44, as viewed in Figure 2. Continuing from this point, the cable runs around the sheave 55a across to the sheave 51a, and then back to the inner groove of the sheave 58a from whence it passes downwardly and under the inner groove of the sheave 49 on the opposite or upper side of the table, as shown in Figure 2. This sheave 49 is the same in construction as the sheave 49 at the other end of the rod 5|, except that the parts are reversed. The cable comes up and around the inner groove and then through the opening in Vthis sheave and outwardly and upwardly over the outer groove in the sheave and then downwardly and under the outer groove in the seave 58a, and so on back to the point of beginning at the turn-buckle 41 on the upper side of the table, as viewed in Figure 2.

The cable, therefore, is in reality a continuous cable which is reeved between the two sides of the table and secured at two points in its length to the opposite ends of the cross beam 44.

As stated, the sheave 55 is held in place by a suitable bracket 56 as is also the sheave 55a. The sheaves 51 and 51a are held in place by brackets 6 l, and the sheaves 58 and 58a are mounted upon suitable pins 62 which project from the side of the beams 8.

The operation of the parts so far described'will now be briefly set forth. Assuming that the table is in its raised position, as shown in Figures 1, 2, and 3, and that a lowering operation is desired, the motor is started in the direction necessary to rotate the screw 33 so that the arm 44 will be drawn tothe left. This, of course, will pull on the cable 54 at the two points 48, causing movement around the various sheaves in such a way as to rotate the crank sheaves 49A in a counter-clockwise direction, so that the crank arms 50 will pull on the connecting rods 53 in order to swing the legs I5 on their pivots I8 and thereby collapse the table.

As the legs swing, the rollers 24 and 26 at their bottomsV will pass over the cams 38 which cooperate with the Yvarious lever mechanisms in such away as to greatly reduce the variation in power demanded fromrthe prime mover or motor 32. This will be more apparent upon inspection of Figures 5 and 6. i

When the table is in its upright position, as shown in full lines at the right-hand side of Figure 5, it will, of course, carry the entire weight of the axle 63 with its wheels 64, shown in dotand-dash lines in position upon the rail sections l. This weight or load in certain of the large size locomotives of the present may amount to approximately 50,000 pounds per axle, so that at this moment the table is supporting 50,000 pounds of load, as shown in the graph of Figure 6. The rollers 24 and 26, however, do not reach the cams 30 until after the table is dropped approximately two inches, let us say. The power necessary at this point when the upward incline of the cam surfaces is eiective is approximately 8,000 pounds, as shown in the graph, and during: the. next ten inches of travel of the table downwardly from its raised position, or, namely,

Auntil the table has been lowered twelve inches,

the powerv required on the toggle operating mechanism" is approximately constant, namely, 8,000 pounds. The peak of the cams is reached after the table `has been collapsed twelve inches, as shown in the graph, and, of course, the power required immediately drops sharply, so that in the next two inches as the rollers ride down the far side of the cams 38, the power required from the toggle operating mechanisms drops to something under 5,000A pounds, and from here on there is a steady drop throughout the balance of the lowering movement which, in the present instance, is assumed tobe approximately thirty inches. After the thirty inch drop, the power required on the toggle is only approximately 1,500 poundsi During this time, the load, of course, drops very quickly from its total of 50,000 poundsy .down to its total of approximately 2,500 or 2,600 pounds during the first five inches of travel of the table in a downward direction. From here on tothe end of the downward movement, the load carried by the table, of course, is constant, since the only weight is the weight of the axle with its wheels and associated parts. The load does not come down to its minimum,-

Vnamely, 2,500 or 2,600 pounds, until after the springs normally used in supporting the weight of a locomotive are completely unflexed. This occurs after the table has travelled downwardly approximately iive inches and, when it occurs, the load, of course, immediately becomes constant throughout thel balance of the motion of the table.

In raising the table just the reverse action takes place, and it will be seen upon analysis of the graph in Figure 6 that I have sol-arranged the toggle and crank operating mechanisms in their relation to the cam surfaces as to reduce to a minimum the variation in powerV demanded of the prime mover.` According to the graph, which represents average conditions, this power demand vares approximately from 1,500 pounds to 8,000 pounds, while, in previous tables of the screw type, this variation has been. from ap. proximately 2,000 pounds to 50,000 pounds.

Referring specifically to Figure 5, I should like to'point out that when raising the table there is a net upward movement of the table of only two inches between the time that the rollers 24 and 26 are at the high points of the cams 30 and the time that the table is fully raised, as shown in full lines. During this time, however, I arrange to apply approximately 40% of the movement of the-primary power mechanism so that the leverage obtained is exceedingly great and requires only an application of power never exceeding approximately 8,000 pounds under the conditions of load assumed. The first 60% of the movement of the power mechanism occurs as the table moves from its lowered position approximately twenty-eight inches of its upward motion, and during this twenty-eight inch movement and just before the. complete load of the locomotive is taken by the table, the rollers 24 and 26 ride upward to the high point of the cams 38. Therefore, the amount of power necessary to move the rollers over the cams during a raising operation is never excessive, and the arrangement is such as to make available a much greater degree of power at the time when it is 'actuallyneededg namely, during'lthe last couple of inches of movementl ofthe table. when the table begins to assume the full load of the portion of the locomotive associated with vthe axle and wheels which it is carrying.

It will be understood, of course, lthat the upper ends of vthe legs I5 are guided inthe channels ii so that'they move in a straight up-anddown direction until such time as the lowering operation has gone suiiiciently far to bring the ends of the rails 1 below the channels Il. When this occurs, the table is practically in its full lowered position andcan be movedto the left, as shown in dot-and-dash lines. in Figure 5. When in the left-hand position the table can, of course, be raised in order to bring the rails 'l in line with the rails 'l' so that the wheels may be rolled off in order to receive whatever work they may require. The dot-and-dash line position at the left of Figure 5 represents the completely collapsed position of the table,A and the dot-and-dash line position at the rightV of Figure 5 represents the position of the parts at the time that the rollers 24 and 26 are atthe high points on the cams 30.

I claim: Y

' l. A drop-table comprising inv combination, a frame for receiving theload, a pair of Vlegs at each side of the frame pivoted thereto, means constraining the two legs of each pair to move in unison, an operating crank for each pair of legs whereby the legs may be swung on their pivots to lower'or raise the frame, and a power means including a movableY Cross beam,'and cable means connected to the-beamand 'reeved between the two cranks. l

2.V A drop-table comprisingin combination,` a frame for receiving the load, supporting legs pivoted to the frame, crank means on the frame adapted to swing said legs on their pivots to lower or raise the frame, a power means carried by the frame, and cable means reeved between the power means and said crank means.

3. AVdrop-table comprising in combination, a frame for receiving the load, supporting `legs pivoted to the frame, a movable cross beam, a motor for moving said beam, a crank connected to the legs on one side of the frame, a second crank connected to the legs on the other side of the Ytrarne, and a continuous cable means connected to the ends of said beam and reeved between the cranks.

4. A drop-table having asupporting means ivoted to each of two opposite sides thereof whereby the table may be raised and lowered, an operating crank for each of said pivoted supporting means, a power means including a movable cross beam, and an endless cable means for actuating said cranks, said cable means being connected to the ends of saidrbeam and reeved between the two cranks.

5. Drop-table equipment comprising in combination, a frame for receiving the load, supporting legsV pivoted to the frame, crank means for swinging the legs on their pivotsso as to lower the frame, means for guiding the frame during up and down movement thereof, power means for moving the crank means, and ca'm surfaces over which the lower ends of the legs are adapted to pass, "saidca'm surfaces being arranged tocooperate with the. crank means in such Way as to reduce to a minimum the variation in power requirementsover therange of movement of said frame. Y

6. Drop-table equipment comprising in combination, `a frame for receiving the load, sup'- porting legs pivoted to the frame, means on the frame adapted to swing said legs on their pivots to lower or raise'the frame, guide means for the upperiends of the legs, and cam means over which the lower ends of the legs are adapted to pass.

1 '7. A drop-table comprising in combination, a frame for receiving the load, supporting legs pivoted to the framecrank means on the frame adapted to swing said legs ,on their pivots to lower or raisethe frame, a powermeans on the frame for operating said crank means, a cable means reeved between the power means and said crank means,.and guide means for the upper ends of the legs.

- 8. A drop-table comprising in combination, a frame for receiving the load, supporting legs pivoted-to the frame, crank means on the frame adapted to swing said, legs. on their pivots tolower or Araise the frame, a power means on the frame for operating said crank means, a cable means reeved betweenthe power means and said crank means, guide means for the upper endsof thelegs together with cam means over which the lower lends of the legs are adapted to pass.

9. Drop-tableV equipment comprising in combination, a frame for receiving the load, supportinglegsrpivoted to the frame, power means carried by the frame for swinging said legs to lower or raise. the frame, and-cam means over which thelower ends ofthe legs are adapted to pass, said; cam means being arranged to increase the travel of the power means near the upper range of movement of said frame.

10. Drop table equipment comprising in combination, a frame for receiving thev load, supporting legs pivoted to the frame at their upper ends and having their lower ends adapted to move horizontally, power means carried by the frame for -moving the lower ends of said legs horizontally so as to swing them on their frame pivots and thereby lower or raise the frame, guide means on the wall of the pit, and means on the table adapted to/cooperate with said guide means to insure vertical movement of the frame as the lower ends of the legs are moved horizontally.

ll. Drop table equipment forrrailway vehicle axles comprising-in combination, a frame, supportinglegs pivoted to the frame at their upper ends and having their lower ends adapted to move horizontally, powermeans carried by the frame forrmoving the lower ends of said legs horizontal- Ly soas to swing them on their frame pivots and thereby lower or raise the frame, rails on the frame adapted to align with adjacent railway trackage, and vertical guide means on the sides of the pit with which the ends of the rail are adapted to cooperate in order to ensure vertical movement of the frame as the lower ends of the legs are moved horizontally.

LAWRENCE RICHARDSON.

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