US1852544A - Jack - Google Patents

Description

April 5, 1932.

l. A. wEAvil-:R

JACK

l. A. WEAVER pril 5, 1932.

JACK

Fi1ed .May 11, 1929 3 sheets-Sheet' 2 um mmmm mp3, mm

"Irl

my mm (mu il. A. WEAVER April 5, 1932..

Filed May 11, 1929 l5 Sheets-Sheet 3 Patented Apr. 5, 1932 UNITED STATES PATENT OFFICE IEA A. WEAVER, OF SPRINGFIELD, ILLINOIS, ASSIGNOR T WEAVER MANUFACTUR- ING OMPANY, OF SPRINGFIELD, ILLINOIS, A CORPORATION OF ILLINOIS JACK Application 1aed may 11, una. semi No. 362,169. v

My invention pertains to improvements in lift-mg jacks, and concerns more particularly those of the truck type, one of the leading" aims and prime purposes of the new con struction being the employment of the cylinder, in which the power piston or plunger slides for operatin Athe jack, as the main frame of the app iance, thereby effecting simplicity in structure, operating strength and economy in manufacture.

This and other features of novelty and advantage, both structural and functional, are incorporated in many of the mechanical elements of the jack and in their cooperation la with one another.

A salient characteristicof the new applii ance is the provision of a jack of this ind plain in structure, with adequate strength to perform its work and which may be easily operated andcontrolled. g

To enable those acquainted with this art to understand the invention fully, in the accompanying drawings, forming a part of this specification, and to which reference should 1J be had, a present desirable and preferred embodiment of the invention has been illustrat ed in detail, like reference characters designating the Vsame parts being used throughout the several View Y ln these drawings: Figure 1 is a side elevation of the improved truck jack showing the lifting saddle in its lowermost position;

kFigure 2 1s a plan view of the ack;

Figure 3 is a substantiallycentral, ver ical. longitudinal section through the jackde" ieting the lifting saddle or seat in dotted lines in its uppermost position;

Figure 4 is a fra mentary, horizontal section on line 4-4 o Figure 3 on an enlarged scale; l

Figure 5 is an enlarged vertical section of a portion onlyof the structure, as is shown in Figure 3;

Figure 6 is a partial elevation and partial section of the release valve and'its operating mechanism on an enlarged scale on llne 6-6 of Figure 4; and

. Figure 'E' is a cross-section on line 7-7 of Figure 5..

By reference to these drawings,`it will be perceived that the jack comprises a main, longitudinal, horizontal, tubular member or cglinder 11 which, near one end, has welded t ereto a pair of oppositely7 extended beari 5 ings or supports l12, 12 accommodating a shaft 13 on which a pair of carrying-wheels 14, 14 are revolubly mounted.

Adjacent to the other end of this main sup porting member 11, a pair ofl outstanding brackets 15, 15 are welded to its outer. face, and each accommodates a suitably-supported caster-wheel 16,V whereby the frame of the truck jack is supported bythe four wheels and may be readily shifted to any desired position by reason of the readily controlled action of the caster-Wheels, v

Along its top, near one end, the tubular member or cylinder is len hwise slotted at 17, and adjacent to one en of such opening, an upstanding, bearing bracket or support i 18 is welded for the accommodation of a fulcrum-pin 19 of a bell-crank lever 21, which, in its lowermost position, as shown in full lines in Figure 3, is largely accommodated inside of the cylinder 11.

At its free end, lever 21 has a bracket or support 22 fulcrumed thereon at 23, such part 22 having a circular, top, plate portion 24 on which the load saddle or seat 25, with its upstanding projections 26, 26, is revoluble, a depending, marginal flange 27 of such element being s un around the underside ofthe periphery o the bearing 24, whereby the member 25 may be readily turned on its support, and, since it is not perforated, and, due to its specified connection with the member 24, this bearin is fully protected from dirt and water an it also assists preventing foreign matter from reaching the bearings of the rockingly connected elements beneath it.

In order to maintain the horizontality of the seat or saddle 25 in all of its various positions, the part 22 is connected to the stationary support 18 by a pair of links 28, 28 positioned on opposite sides of the bell-crank lever 2 1'. l

To assist in the descent of such lever and its loadsaddle, when there is no weight ixn- 1w posed on the latter, a coiled, contractile spring 29 is connected at one end to the member 22 and at its other end to a suitable lug roller 32 which bears on and cooperates with one end of .the plane face of a plunger 33 fitting and slidable in the cylinder 11 and supplied with an a propriate leather or other packing 34 to e ect a snug sliding lit with the inner surface of the cylinder.

' i' From theforegoing, it will be clear that,

when this plunger-or piston is forced to the right, as the parts are viewed in Fig. 3,the

p bell-crank lever will be rocked upwardly to carry its saddle and the load in the same direction, and, when suchplunger is permitted to travel to the left, the load-saddle and lever can descend.

An end` casting 35 of irregular shape, as shown in Fi re 5, is screwed into the opposite end o the cylinder 11 and its hub 36 supports an internal, smaller pump-cylinder 37 which at its inner end carries a stationary va ve casting 38 supplied with a leather or other appropriate packing 39 tightly fitting against the inner surface of the cylinder 11 and constituting a stationary wall dividing the cylinder intopower and reservoir portions 52 and 51, respectively.

As is clearly shown insueh Figure 5, the `element 38 has a spring-pressed vball-valve controlled conduit 41 connecting the space or reservoir between the cylinders 37 and l1 and the insideof 1the cylinder 37, another spring-pressed ball-,valve controlled passage 42 connecting the interior of the cylinder 37 with the inside of the cylinder 11 to the right of the member 38. A

A pump plunger 43, fitted with a suitable packing 44, is slidable inside of the cylinder 37 and extends out oneend thereof through a stuiiing box 44', the exposed or protruding end of the plunger being connected by a link 45 to a short extension 46 forming a part of a hollow, operating handle 47 fulcrumed on the exposed portion of the casting' 35 on a suitable pin 48, such handle desirably being fitted with a top cross-piece 49 by which it may be readily grasped for actuation. 1

Assuming that the oil-reservoir 51 between the cylinders 37 and 11 is supplied with an appropriate quantity of oil, it will be clear that every time the handle 47-49 is rocked upwardly, causing the travel of the piston or plunger 4 3 to the left, oil will be sucked into the cylinder 37 through the valve-'controlled passage 41, and that, whenthe handle is subsequently rocked downwardly, forcing the piston -or plunger 43 to the right, the oil in the cylinder 37 will be expelled through the valve-governed passage 42 into the power portion 52 of the cylinder, causing the travel of the piston or plunger 33 tothe ri ht and effecting a corresponding rocking of t e bellcrank lever and the lifting of the s addle and its load. Repetition of these movements will produc progressive or-step-by-step elevation of the load. A Obviously, in order to permit descent of the saddle and the Weight imposed thereon, it is necessary to provide means to allow the oil in the power-cylinder 52 to escape back into the reservoir'51, and the size of such conduit will, of course, control the speed of downward movement.

To this end,the passage'42, to the right of,

. its ball check-valve, is connected to an anguf lar conduit 53, extending to the other side of the member 38, at which place it has a suitable valve-seat controlled by a conical valve 54, the stem of which projects through appropriate stuing-boxes 56'in the reservoir piston, described hereinafter, and 57 in the end casting 35.

A spring 58 surrounds the external part of such Valve-stem and bears at `one end against the element 35 and at its other end against an adjustable, enlarged head 59 on the stem, the end of such head cooperating with a cam 61 appropriately mounted in a bearing 62 forming part of the casting 35 and supplied with an operating handle 63 by which it may be readily turned.

When thecircular portion of the cam 61 bears on the head 59, as shown in Figures v4 and 6, lvalve 54 closes the passage 53, but, when the handle 63 is turned `to allow the fiat side of the cam to come into register with the head 59, the spring 58 expands somewhat and opens the valve 54, thus establishing direct communication between the power-cyl-` inder 52 and the oil-,reservoir 5l, permitting the oil in the former to flow at a denite, slo'w .speed into thev latter, thus allowing the bellcrank lever and its saddle and load to descend at a predetermined rate.

It is desirable to provide means to permlt a relatively quick, but not necessarily owerful, initial lift of the saddle to the loa, after which, they may be elevated together more slowly by the intermittent pump action already presented, and, for the purpose of accomplishing this rapid preliminary lifting,

the following specified cooperating instrumentalities have been provided.

. An annular or centrally-apertured iston 64 in the reservoir 51 has a hub 65 slida le on the exterior surface of the pump-cylinder 37 and it also is fitted with a double leather or other suitable packing 66 which maintains a fluid-tight relation 'with the inner surface of the cylinder 11 and the outer surface ofthe pump-cylinder 37.

A coiled spring 67 encircles thev pump-cylinder 37, bearing at one end against the division-wall or valve member 38 and-pressing at its other end against the piston 64, tending to shift the latter to the left as the parts are viewed inthe drawings.

lPiston 64 has an operating rod 68 fixed thereto at 69 (see Fig. 4), the rod extending through a stuffing-box 71 in the closure member 35, its end cooperating with an arm 72 fixed on a rock-shaft 73 mounted in the casting and supplied with a foot-piece or pedal 7i., the depression of which rocks the shaft and arm 72, causing the rod 68 and its associated reservoir-piston 64 to travel to the right.

Such movement of the piston expels oil :trom the reservoir 51 through the passages lil and 42 into the power-cylinder 52 pushing the piston 33 to the right and lrapidly rocking the bell-crank lever and its saddle up to the load.

its soon as the seat or saddle engages or almost touches the load, there is no further depression of the pedal, and, by the rocking of the handle Lill-#19, the load may. be lifted step'by step, the oil for this purpose being ltaken trom that portion of the reservoir 51 between the member 38 and the reservoirpiston 6i.

titated somewhat differently, the quick, tiret-stage raising of the seat or saddle is brought about by reducing the size of the oilreservoir and the expulsion of a portion oi its contents into thepower-cylinder.

its soon as the foot is released from the pedal. 74, the expansion of the previouslycontracted spring 67 pushes the reservoir-v piston @t to the left to its limit of movement, and, to facilitate this action, the piston 64 is provided with a passage 75 through it which is controlled by a leatspring valve 76 secured against the right-hand face of the piston by a screw 77.

"When the piston 64 moves to the right, auch valve 76 automatically closes the passage 75, whereby the iston may 'expel oil ahead ot it, but, when t e piston moves to the lett under the action of its spring 67, the valve 76 opens ot itself to permit the oil to flow through the port 75.

ln order to malte certain that the valve 76 will be open when the piston is at the extreme et its lett hand movement, so that the oil on both sides ot the piston is available to the pum a, a stationary rod 78 is mounted on the mem er 36 and projects through the port 775 sutliciently to hold the spring valve o pen asis clearly illustrated in Figure 5.

@ome small quantity of oil, during the operation ot the Jack, may escape or leak pastthe plunger 33, and, to restore such oilto the reservoir, a shallow dam 79 is provided across the bottom ot the inside of the cylinder l1 in advance ofthe plunger 33 the space to the left of such shallow wall being connected to that portion of the reservoir tothe left of the `resinrvoir-piston 64 'by a pipe 81, whereby,

From the foregoing, it will be apparent v that the saddle may be quickly elevated to the load by foot actuation of the relatively-short pedal 7l', and that, thereafter, by the upward and downward hand rocking of the compaia tively-long handle 47-49,'the load may be raised intermittently or 4step-by-step, its descent when desired, being permitted by hand or foot turning of the handle 63 to open i the discnhargewalve 54, thus allowing the oil to return from the power-cylinder into the reservoir at a predetermined, slow, regulated speed.

Those trained in this art will readily understand that this invention is not limited or restricted to the precise and exact details of structure presented and that many minor mechanical changes may be incorporated in the appliance without departure from the heart or essence of the invention, as delined by the appended claims, and without the loss of any of its material benefits or advantages.

i rom what precedes, it will be clearthat since the power-cylinder,' its valves, its plunger and the operating means therefor, and the reservoir piston are all mounted on a single casting screwed into the end of the main frame cylinder, these several elements may be demounted from the structure as a unit for repairs or replacement of worn parts by merely unscrewing the part 35 fromthe cylinder, which 'demounting operationmay be facilitated by turning or rotating the handie 47 and its cross-bar 49 as a means for bringing Aabout the separation of the members.

l claim:

l. ln a lifting-jack, the combination of load-engaging means, a power-cylinder, a piston slidable in said cylinder', means operatively connecting said piston and load-engaging means, a liquid-reservoir, a pump including a cylinderand piston to force li uid from said reservoir into said cylinder to s ide said piston to raise said load-engaging means, means to permit return of the said liquid in said power-cylinder into said reservoir to allow movement of said piston to permit the descent of said load-engaging means, and means to reduce the size of said reservoir-and vthereby `force liquid therefrom into said power-cylinder to obtain a quick initial ascent o'E said load-engaging means.

2. In a liting-jack, the combination of load-engaging mea-ns, a power-cylinder, a piston slidable in said cylinder, means operatively connecting said piston and load-engaging means, a liquid reservoir, a pump including a cylinder and piston to force liquid intermittently from said reservoir into said power-cylinder to slide said piston to raise said load-engaging means, means to permit return of the liquid in said power-cylinder4 into said reservoir to allow movement of said piston to permit the descent of said load-engaging means, and means to steadily reduce the size of said reservoir and thereby force liquid therefrom into said power-cylinder to obtaina quick initial ascent of said load-engagin means.

3. n a lifting-jack, the combination of load-engaging means, a power-cylinder, a piston slidable in said cylinder, means operatively connecting said piston and load-engaging means, a liquid reservoir, a hand-operated pump to force liquid intermittently from said reservoir into said cylinder to slide said piston step-by-step to raise said load-engaging means correspondingly, means to permit the return of the liquid in said power-cylinder into said reservoir to allow movement of said piston to permit the descent of said loadengaging means, and foot-operated means to steadily yreduce the size of said reservoir andA thereby force liquid therefrom into said power-cylinder to obtain a quick initial ascent ofsaid load-engaging means.'

4. In a lifting-jack, the combination of load-engaging means, a power-cylinder, a power-piston slidable in said cylinder, means operatively connecting said piston and loadengaging means, a pump-cylinder connected to said power-cylinder, a liquid reservoircylinder connected to said pump-cylinder, a hand-operated plunger slidable in said pump-cylinder to draw liquid from said reservoir into said pump-cylinder and to force it therefrom into said power-cylinder to operate said power-piston step-by-step to raise said load-engaging means correspondingly, means to permit return of the liquid from said power-cylinder into said reservoir to allow movement of said power-piston to permit the descent of said load-engaging means, a foot-operated piston slidable in sald reservoir-cylinder to force liquid therefrom steadily into said power-cylinder to obtain a quick initial ascent of said load-engaging means.

5. In a lifting-jack, the combination ofload-engaging means, a power-cylinder, a power-piston reciprocatory 1n said cylinder,

means operatively connecting said powerpiston and load-engaging means, a liquid reservoir-cylinder, apump connected to said reservoir and to said power-cylinder and adapted to force liquid from the former into the latter to operate said power-piston to raise said load-engaging means, means to permit return of liquid from-said power-cylinder linto said reservoir-cylinder to allow descent of said load-engaging means, a ported piston slidable in said reservoir-cylinder to force liquid therefrom into said power-cylinder'to obtain a quick initial lift of said load-engag ing means, means to operate said reservoirpiston, and a valve controlling said reservoirpiston port to close it automatically when the piston is'moved in the direction to feed liquid into said power-cylinder and to open it automatically when it travels in the opposite direction.

6. In a lifting-jack, the combination of load-engaging means, a power-cylinder, a power-piston reciprocatory in said cylinder, means operatively connecting said power-piston and load-engaging means, a liquid-reservoir cylinder, a pump connected to said reservoir and to said power-cylinder and adapted to force liquid .from the former into the latter to operate said power-piston to raise said load-engaging means, means to permit return of liquid from said power-cylinder into said reservoircylinder to allow descent,

tubular-member, carrying-wheels for said member, a load-engaging member, a longitudinal portion of said tubular member con stituting a power-cylinder, a power-piston of substantially the same diameter as the interior of and slidable in said power-cylinder, means operatively connecting said powerpiston and said load-engaging means, another longitudinal yportion of said tubularmember constituting a liquid-reservoir, a smaller pump-cylinder in said reservoir-cylinder connected to the latter and to said power-cylinder, a pump-plunger reciprocatory in said pump-cylinder and adapted to force liquid from said reservoir into said power-cylinder to operate said power-piston and load-engaging means, means to permit return of liquid from the power-cylinder into said reservoir-cylinder to allow descent of said load-engaging means, a reservoir-piston surrounding and slidable on said pump-cylinder'and adapted to force liquid from said reservoir into said power-cylinder to obtain a quick initial lift of said load-engaging means, and meansto operate said reservoirpiston.

8. In -a lifting-jack, the combination of a tubular-member, carrying-wheels for said member, a load-engaging member, a longitudinal portion of said tubular-member constituting a power-cylinder, a power-piston of till ` der into said reservoir, a reservoir-piston.

substantially the same diameter as the interior of and slidable in said power-cylinder, means operatively connecting said powerpiston and said load-engaging means, another longitudinal portion of said tubularmemloer constituting a liquid-reservoir, a smaller pump-cylinder in said reservoir-cylinder connected to the latter and to said power-cylinder, a hand-operated pump-plunger reciprocatory in said pump-cylinder and adapted to force liquid from said reservoir into said power-cylinder to operate said power-piston and load-engaging means, means to permit return of liquid from the power-cylinder into said reservoir-cylinder to allow descent of said load-engaging means, a reservoir-piston surrounding and slidahle on said pump-cylinder and adapted to force liquid from said reservoir into said powercylinder to obtain a quick initial lift of said load-engaging means, and foot-actuated means to operate said reservoir-piston.

9. ln a lifting-jack, the combination of a substantially-horizontal tubular-member one longitudinal portion of which forms a powercylinder and another lengthwise section of Which constitutes a liquid-reservoir cylinder, carrying-wheels Jfor said tubular-member, a load-saddle, a power-piston slidable in said power-cylinder, means 'operatively connecting said power-piston and saidtload-saddle, a closure for one end of said tubular member, a pump-cylinder mounted inside of said reservoir-cylinder on said end closure and connected to said reservoir and to the said powercylinder, a plunger reciprocatory in said pump-cylinder, means to operate said plunger to Aforce liquid from said reservoir into said power-cylinder to slide said power-piston to raise said load-saddle, means to permit return of liquid from said power-cylinslidable in said reservoir-cylinder on the. outside oi' said pump-cylinder and adapted to torce liquid from said reservoir into said power-cylinder to obtain a quick initial lift of said load-saddle, and means to operate said reservoir-piston.

l0. ln a lifting-jack, the combination of a substantially-horizontal tubular-member, carrying-Wheels for said tubular-member, a cross-wall inside of said tubular-member dividing it into a power-cylinder and a reservoir-cylinder, a load-saddle, a power-piston reciprocatory in said power-cylinder, means operatively connecting said power-piston and said load-saddle, a closure for one end of said tubular-member, a pump-cylinder inside of said reservoir-cylinder and mounted on said end closure, said division-wall being mounted on said pump-cylinder valved conduits connecting said pump-cylinder with [said reservoir and power cylinders, a plunger reciprocatory in said pump-cylinder to force liquid from said reservoir into said powericylinder to actuate said power-piston to raise said load-saddle, means to operate said pump-plunger, means to permit return of liquid from said power-cylinder into said reservoir to allow descent of said load-saddle, a reservoir-piston surrounding and slidable on said pump-cylinder in said reservoir-cylinder` and means to slide said reservoir-piston to force liquid from said reservoir into said pump-cylinder to obtain a quick initial lift of said load-saddle.

11. In a lifting-jack, the combination of a main-cylinder, a movably-mounted loadsaddle, a piston of substantially the same diameter as the interior of and slidable in said cylinder and operativel associated with said saddle, a pump-cylin er, valve means for said'pump-cylinder, a plunger sli-dable in said pump-cylinder to actuate said piston by liquid pumped by said plunger, means to operate said plunger, a liquid-reservoir, and means to force liquid from said reservoir through said pump-cylinder valve means to obtain a' quick initial lift of said saddle through movement of said piston'.` 12. In a frameless liftingjack, the combination of a substantially-horizontal cylinder, front and rear carrying-wheels for the opposite end portions of said cylinder, said cylinder constituting the sole, main, supporting member between said front andfrear carlying-wheels, a load-saddle, means mounting said load-saddle` on said cylinder with capacity for elevation aud descent of the saddle, a piston of substantially the same diameter asthe interior of and slidable in said cylinder, means operatively associating said piston with said saddle mounting, and means to pump fluid in said cylinder and to permit its release to actuate said` piston to raise and to lower said saddle.

13. In a frameless lifting jack, the combination of a substantially-horizontal tubular-member of substantially uniform diameter, one longitudinal portion of which comprises .a power-cylinder and another longitudinal portion of which forms a liquidreservoir, front and rear carrying-wheels for the opposite end portions of said tubularmember, the latter constituting the sole, main, supporting member between said front and rear carrying-Wheels, a piston of substantially the same diameter as the interior of and slidable in said power-cylinder, a load-saddle, means mounting said load-saddle on said cylinder with capacity for elevation and descent of the saddle, means operatively connecting said piston and saddle mounting2 means to pump liquid from said reservoir into said power-cylinder-to actuate said piston to raise said load-saddle, and means to permit flow of said liquid from said power-cylinder into 'said reservoir to allow return movement of said piston and the l descent of said load-saddle.

. nation of a main substanti 14. In a frameless lifting-jack, the combination of a substantiall -horizontal cylinder slotted along its top or a portion of its length, frontl and rear carrying-wheels for the opposite end portions of said cylinder, the latter constituting the sole, main, supporting member between said front and rear carrying-wheels, a bell-crank lever fulcrumed on said cylinder, a load-saddle mounted on said lever, the latter in the lowermst position of said saddle extending through said slot and being, at least in part, accommodated in said cylinder, a piston of substantially the same diameter as the interior of and slidable in said cylinder, means operatively associating said piston with said lever, means to pump fluid into said cylinder and to permit its release therefrom to actuate said piston to raise and to lower. said saddle.

15. In a frameless lifting-jack, the combination of a substantially-horizontal tubularmember slotted along its top for a portion of its length, another longitudinal section of said member comprising a power-cylinder,

and a third lengthwise portion of said member forming a liquid-reservoir, front and rear carrying-wheels for the opposite end portions of said tubular-member, the latter constituting the' sole, main, supporting member of the jack between said front and rear carrying-wheels, a piston of substantially the same diameter as the interior of and slidable in said power-cylinder, a load-saddle, operating means extended through the slot of said tubular-member and operatively connecting said piston and load-saddle, means to pump liquid from said reservoir into said powercylinder to actuate said piston to raise said load-saddle, and means to permit flow of said liquid from said power-cylinder into said reservoir to allow return movement of said piston and the descent of said load-saddle.

16. In a frameless lifting-jack, the combination of'a main substantially-horizontal cyllinder, front and rear carrying-wheels for the opposite end portions of said cylinder, the latter constituting the sole, main, supporting member of the jack between said front and rear carrying-wheels, a load-saddle, a. iston of substantiall the same diameter as t e interior of and s 'dable in said c linder, means operatively associating said piston with said saddle, a pump-cylinder` demountably sugported in said mam c linder, a plunger sli able in said pum -cy inder, valve means for said pump-cylin er, and means to operate said plunger to actuate said piston through the means of liquid pumped in said pumpcylinder.

17. In a framele lifti -Jacln'the combiy-horiz'ontal cylinder, front and rear carrying-wheels for the opposite ends of said cylinder, the latter constituting the sole, main, supporting member of the jack between said front and rear carrying-wheels, a piston of substantially the same diameter as the interior of and slidable in said cylinder, a load-saddle, means operatively associating said piston with said saddle, a pump-cylinder in said main cylinder, a plunger slidable in said pump-cylinder, valve means for said pump-cylinder, means to operate said plunger to actuate said piston through the means of liquid pumped in said pump-cylinder, and means supporting said pump-cylinder, plunger and plunger-operating means as a unit demountably in said main cylinder.

18. In a frameless lifting-jack, the combination of a substantially-horizontal cylinder with a slot through its top, front and rear carrying-wheels for the opposite end portions of said cylinder, said cylinder constituting the sole, main, supporting member between said front and rear carrying-wheels, a power-piston slidable in said cylinder, hydraulic means to slide said piston in said cylinder, a load-saddle, means rockingly mounting said saddle on the top of said cylinder and adapted to occupy said slot, means operatively connecting said piston and saddle mounting, and spring means housed in said cylinder in substantially horizontal relation in the lowermost position of said saddle and tending to hold the latter down and extending up through said slot in the uppermost position of said saddle.

19. In a frameless lifting-jack, the combi'- nation of a substantially-horizontal cylinder having a slot through its top, front and rear carrying-wheels for the opposite end portions of said cylinder, said cylinder constituting the sole, main, supporting member between said front and rear carrying-wheels, a bell-crank lever fulcrumed on said cylinder and having an arm projecting down through said slot, a load-saddle mounted on said lever, an anti-friction roller on said lever-arm, a

ower-piston slidable in said cylinder and earing against said roller, and means to slide said piston to raise or to lower said lever and load-saddle.

In witness whereof I have hereunto set my hand.

IRA A. WEAVER.

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