US1928490A

US1928490A - Elevating truck

Info

Publication number: US1928490A
Application number: US611476A
Authority: US
Inventors: Daniel E Hennessy
Original assignee: SHEPARD CO LEWIS
Current assignee: LEWIS-SHEPARD Co; SHEPARD CO LEWIS
Priority date: 1932-05-16
Filing date: 1932-05-16
Publication date: 1933-09-26
Anticipated expiration: 1950-09-26
Also published as: GB398133A

Description

Sept 26, m33 D. E. HENNEssY 1,928,490

vELEVA'I' ING TRUCK Filed May 16, 1952 5 Sheets-Sheet l inver-Nor. Daniel El-lennessy bywww AIB/S.

LQZSAQ@ Sept 26, i933. D, E, HENNEssY ELEVAT ING TRUCK Filed May 16, 1932 3 Sheets-Sheet 2 mw.. ma 001m@ oN n@ mw s. W A

Sept. 26, 1933. D. E. HENNESSY ELEVAT ING TRUCK Filedv May 16, 1932- 5 Sheets-Sheet 3 lnvenToT Donie E. Hennessy byfewmw Ays Patented Sept. i933 y, nLnvA'riNe TRUCK n Daniel E. Hennessy, Watertown, Mass., assigner to,` Lewis- Shepard Company, Watertown, Mass., `a corporation of Massachusetts Application May 16, 1932. Serial No. 611,476

i2 claims. (c1. 25e-.im

This invention relates toimprovements in ele- Y vating trucks comprising'a frame andload supporting means mounted thereupon adapted to be raised relatively to the frame in such manner that 5 the truck, with the load supporting means in lowered position, can be introduced beneath a loaded platform or skid, with means operable to raise the loadsupporting means, thereby lifting the platform or skid from the floor and permit its transportation. i f

In usual trucks of this character the `load supporting means is either raised vertically relatively to the frame, or moved forwardly relatively to the frame, the upward movement of the load supporting means being caused byparallel links,

cci-operating rever'sely inclined surfaces, or otherwise. In elevatingtrucks of thetype` in which the load supportingl means is `moved rforwardly andr upwardly, a reverse movement is required to lower the load supporting means by moving it Vdownwardly and rearwardly. This manner of lowering the load is likely to cause'a great deal of damage to loads, such as bags of flour, cement, etc., by abrasion during kthe descent when contactingwith adjacent loads, and is subject to a great deal of complaint by users.

One of the objects of the present invention is to provide an elevating truck ,which comprises a wheel-supported frame, load supporting means mounted thereon, and means for raising said load supporting means upon movement thereof rearwardly relatively to said frame, including a lifting lever and a thrust member connected thereto operable upon actuation thereof detachably to engage and to shove the load supporting means rearwardly. f f f Y By reason of this construction the load is raised by moving backwardly and upwardly, and lowered 'by moving forwardly and downwardly,A so that during the descent `of the load itmoves away from adjacent piles or loads and eliminates such abrasion. When a load thus deposited is relifted, there is always sufficient space between 5 the load to be lifted and an adjacent pile or load to prevent abrasion.A 'n

If loads are of such a nature that they `are not subject to abrasive damage, and it wouldbe unn desirable to'lose floor space by spacing the loads as above described, the spacing can beeliminated and the loads deposited closeto each other by a light rearward pressure on the tongue when the loads are abutted and lowered. During such an operation the wheel support assumes all of the 5 longitudinal motion and the load itself descends vertically. Upon re-lifting of the load the reverse or forward movement of the wheel frame permits the load to be raised vertically, as will be obvious.

Another object of the invention is to provide a lifting truck in which the load supporting means is raised upon longitudinal rearward movement thereof relatively to the frame, with actuating mechanism which will require a minimum amount of head room. This is accomplished in the present invention by providing the steering post of the truck with ears extending upwardly there,- from a short distance, fulcruming the steering tongue in such ears, and pivoting a thrust member upon the tongue, below the steering post,l with means for automatically positioning the thrust member to engage a'complementary abute ment upon the front end of the load supporting means, and operable upon depression `of the tongue from upraised position first to engage the abutment, and upon further downward movement of the tongue to shove the upper end of the load supporting means rearwardly relatively to the steering mechanism and frame. When the steering tongue is swung `downwardly to normal steering position and the load supporting means lifted in its uppermost position, the ears upon the steering post Vare only slightly above the level of a low dash board upon the load supporting means. By reason of this construction the truck re quires very much less head room thanY trucks heretofore constructed. Furthermore, since the load supporting means is moved rearwardly to raised position, sumcient leewayis provided to permit the tongue, when at a convenient height for steering, to be swung through a complete circle, S-degrees, without engaging the. usual load upon the truck. A l A further object of the invention is to, provide a truck in which injury to the operator, by the exertion of a full liftingeffort upon handle, is prevented.

In usual trucks in which the load supporting means is moved forwardly to raise it from the frame, means, such as a hooked pawLdetachably connects the tongue to the load supporting means. If suchA means are not properly engaged or re leased by momentaryrelief of the pressure upon the tongue, the handle'and load supporting means become disconnected,A so that when the operator' again exerts his full lifting power upon the tongue he is likely to Vfall backward and be injured. Many operators have been seriously injured in this manner. In the present construction this isprevented by automatically positioning the thrust member so' that it will invariably engage the a loadless abutment upon the load supporting means upon depression of the tongue and providing such detachable connection therebetween that the thrust; member will be maintained constantly in engagement with the load supporting means by the weight of the load during the lifting operation.

A further object of the invention is to provide an elevating truck of this character with a gravity-actuated locking pawl having a flat shoulder engaging a rotatable member when in locked position and which can be easily unlocked by the rotation of such member.

Another object of the invention is to provide an elevating truck in which the thrust member is normally supported in position to engage thel load supporting means upon depression of the tongue, but which will permit free steering movement of the tongue.

Another important object of the invention is to provide an elevating truck having a load supporting means movable longitudinally relatively to the frame, with inclined fluid-operated means for checking the descent of the load in which all possible leakage of fluid will not impair the efficiency of the check.

These and other objects and features of the invention will more fully appear from the following description and the accompanying drawings, and will be particularly pointed out in the claims.

In the drawings:

Fig. 1 is a plan view of an elevating truck embodying the preferred formv of the invention;

Fig. 2 is a side elevation of the same showing the load supporting means in lowered position;

Fig.-3 is a front end View of the same;

Fig. 4 is a side elevation of the truck showing the load supporting means in elevated position with the tongue upraised and illustrating in dotted lines the position of the tongue and thrust member during the elevating movement of the load supporting means; and,

Fig. 5 is an enlarged detail longitudinal sectional view of the piston of the release check illustrating in dotted lines the cylinder of the check in which the piston operates.

The elevating truck illustrated in the accompanying drawings comprises a main frame having parallel side bars 1 and 2, having their rear ends bent toward each other at right angles and connected together by a plate overlapping and welded to the abutting ends thereof, and connected at their front ends by an arch-shaped head 3 having an integral central Vboss 4 in which the steering post 5 of the steering mechanism is rotatably mounted. The steering mechanism comprises a cylindrical head 6 in which the steering post is secured and has an upper enlargedilange '7 which engages the lower end of theboss 4. An axle 8 extends horizontally through and is fixed to the cylindrical portion of the steering head, and steering wheels-9 and 10 are mounted upon the respective ends of the axle.

The steering post extends upwardly into and is welded to the base 11 of a bracket having ears 12 and 13 extending upwardly therefrom a short distance. The steering tongue 14 has a bifurcated head 15 the

arms

16 and 17 of which are fulcrumed upon a shaft 18 mounted in the ears 12 and 13. A thrust membeilQ, preferably in the form of a rectangular bar, is fulcrumed upon a pivotal shaft 20 which is mounted in the lower ends of the bifurcated

members

16 and 17 of the head of the tongue, and when the tongue is in upraised position normally rests upon the base 11 of the bracket in such position that upon forward swinging movement of the tongue the thrust member will engage a complementary abutment upon the load supporting means.

A spring 21, which is secured at one end to the thrust member near its free end and at its opposite end to a collar 22 upon the fulcrumed shaft of the tongue, serves to maintain the thrust member in position properly to engage the complementary member upon the load supporting means during the lifting of the load caused by the depression of the tongue. The spring is, however, operable when the load supporting means has been raised to and locked at a predetermined height and the tongue thereafter raised automatically to disengage the thrust member from said abutment and retain the thrust member in such position that it will permit free rotation of the steering tongue without interference with any other part of the truck.

The load supporting means comprises a frame having

side bars

23 and 24 corresponding to and preferably located directly above the side bars 1 and 2 of the main frame. The

rear ends

25 and 26 of the

side bars

23 and 24 are bent toward each other at right angles and their ends abutted. The abutting ends are connected together by a plate 2'7 overlapping the adjacent ends and secured to the

respective portions

25 and 26 by welding, as heretofore described in respect to the frame construction of the truck. A transverse girder 28, having a downwardly extending web 29 and an integral upwardly extending reenforced member or dash board 30. connects the

side members

23 and 24 in proximity to their front ends.

The load supporting means is connected to the frame by front and rear pairs of parallel links. The front pair of parallel links 3l are pivoted at their upper ends to ears 32 integral with and projecting forwardly from the transverse girder 28 by stud shafts 33 which also extend through the front portions of the side bars 24 of the load supporting means. The lower ends of the front links 31 are pivotally mounted upon a transverse shaft 34 which is mounted in rearward extensions 35 of the head 3 of the frame and which also extends through the side members 1 and 2 of the frame. The rear parallel links are pivotally mounted at their upper ends upon a shaft 36 which is mounted in the

side bars

23 and 24 of the load supporting means. The rear link mechanism comprises a two-part frame consisting of pairs of

parallel links

37 and 38 rotatably mounted upon the shaft 36 and welded to a sleeve 39 intermediate of said links, and also to a sleeve 40 extending inwardly toward the center of the load supporting means.

The lower ends of the

parallel links

37 and 38 are pivotally mounted upon a shaft 41 extending transversely across the main frame near its lower end, and mounted in the side bars 1 and 2 of the frame. The rear wheels 42 of the truck are mounted upon the shaft 41 between the

links

37 and 38. A spacing sleeve 43 is interposed between the inner links 38.

The'upwardly extending member or low dash board 30 of the front transverse girder 28 of the load supporting means is provided centrally with a relatively narrow forward extension 44 which is re-enforced by webs 45 integral with the transverse girder, and has a rounded forward edge 46 providing an abutment to engage the re-entrant end 47 of the thrust member 19 which normally swung upwardly slightlybeyond verti- Vio cal position and is held in this position by engagement of the `bifurcated extension of the `tongue with the base of ithe bracket upon the upper end of the steering post. When in this positionthe free end of the thrust member` is separated a short distance from the co-operating abutment upon the load supporting means, so that the steering mechanism can be freely rotated to a complete circlefof S60-degrees. When itis desired'to raise the load 'supporting means, the*` tongue is `swung downwardly in substantially the central plane of the truck. This downward depression of the tongue rst causes the reentrant abutment at the end of the thrust memy movement ofthe load supporting means relatively to the steering mechanism andfframe.

Suitable means arev provided for locking` the load supporting meansY in raised position.

, the construction illustrated a novel locking means is provided which comprises a. gravity-actuated pawl 48 whichl is pivotally mounted at its rear end upon one of the shafts 33 intermediate of the 'forwardly extending ear 32 of the front girder of the load supporting means and the side bar 'cci ' 24. When the load supporting means is inlowered position the pawl 48 rests midway of its length (in upwardly inclined position as shown in Fig. 2) against a shaft-49fwhich is rotatably mounted in suitable ears 50 integral with and extending rearwardly fromthe head 3 of the frame. The free end of the pawl 48 is cut away to provide a notch presenting a shoulder 51 with an end portion 52 projecting therebeyond.` The lower portion of the shoulder is beveled to the under face of the pawl. The length of the pawl is such that when the load supporting means is moved rearwardly and is raised by the action of the parallel links to a predetermined height, slightly before `the parallel links have reached a vertical` position, the shouldered portion of the pawl will drop down into ysubstantially horizontalposition, as illustrated in Fig. 4, and will abut against the rotatable shaft 49, thereby preventing forward movement of the load supporting means and holdingfthe same in elevated position. The rotatable member 49 hassecured to its opposite end an actuating member, such as a forwardly extending `pedal 53, adapted when depressed to rotate the shaft, and thereby cause disengagement of the pawl by the rotating frictienal movement of the shaft upon the abutting shoulder of the pawl. By reason of this construction the pawl can be ydisengaged by very light pressure upon the pedal. y

Counterbalancingfmeans, suchvas a counterweight 54 secured to the shaft 49 and extending rearwardly therefrom, serves to restore the pedal to upraised position when the foot is removed therefrom. e

` Afurther object of the invention, as above stated, is to providey a iiuideactuated dash pot or check mechanism for so restraining the descent of the load supporting means as to prevent injury to the load, in which all'possible leakage of the duidr from the cylinder of the check will not limpairV the efficiency of the check. In usual constructions in which an inclined dash pot is employed, the wearing of the' bushing, in which the piston of the dash pot is mounted, causes a leakage of the fluid from the cylinder of Sil the dash pot, and inasmuch as the extent of the n movement of the piston in the dash pot is always the same, such leakage of the liquid produces an air chamber between the piston andthe remaining fluid in the dash pot, so that when they load supporting means is released itwill descend freely such distance as is permitted by thefaccumulation of air between the liquid and the piston, and upon engagement of the piston with the incompressible fluid will produce a distinct shock or jolt upon the load. The amount of this shock will, of course, increasein proportion to the amount of fluid which -leaksfrom the dash pot during the repeated tiltings of the dash pot vas the load supporting means is successively raised and lowered. The present invention comprises a dash pot construction in which such leakage is obviated. The dash pot or check of the present invention comprises a cylinder pivotally conk nected to the frame and a piston connected to the load supporting means in suchmanner that the dash pot is always in an inclined position. The cylinder, however, is provided with-a supplemental reservoir containing suflicient tiuidY to cause the liquid level therein to be of sufficient height to maintain the portion of the cylinder below the piston completely full at all times and at all inclinations of the rdash pot. y

In the preferred construction illustrated the dash pot comprises a cylinder 55 having a closure 58 .at its lower end provided with ears 57 which are connected by a pivotal rod 58 to a boss 59 which is integral with and extends rearwardly from a transverse channel bar girder 60 which is welded, or otherwise secured, at its ends to the side bars 1 and 2 of the main frame. A cylindrical piston 6l is reciprocably mounted in the dash pot and has a piston rod 62, the upper end of which is connected, preferably by a screw threaded connection, to a boss 63 upon a collar 64 which is rotatably mounted upon the shaft 36 upon which the upper ends of the rear links are pivotally mounted, the collar 64 being interposed between the sleeves 40 of the frame forming the rear parallel link construction. In order to prevent impairment of the eiliciency of the dash pot by leakage of liquid from the portion of the cylinder belowthe piston, the cylinder 55y is provided with an extension 65, preferably of rectangular cross section, forming a reservoir for the liquid; The lower portion, and preferably the longitudinal axis of this extension, is at such an angle to the axis of the cylinder that its lower wall will be substantially horizontal when the load supporting means is in tially the same as that of the diameter of the cylinder, but the vertical depth of the reservoir is considerably greater to enable the end wall 66 of the reservoir to be equipped with a suitable boss 6'7 to contain a bushing for the piston rod 62 and to enable said bushing to be located at least above the minimum level of the liquid in the reservoir and cylinder. f

The front end wall 68 of the reservoir desirably is provided with a boss 69 having a central aperture to provide a filling port which is adapted to be closed by a plug 70. The liquid is introduced into the reservoir until the liquid level therein is noV of such height as to insure complete lling of the portion of the cylinder between the end of the piston and the closed end of the cylinder irrespective of the angle or inclinationof the dash pot and its piston tothe horizontal, and preferably is of a depth sufcient to submerge the upper end of the cylinder irrespective of its inclination, By thus maintaining the portion of the cylinder between the piston and the closed end of the cylinder completely filled at all times, no possible free or uncheckd movement of the piston of the dash pot can occur.

. A preferred piston construction is illustrated in Fig. 5 having valve mechanism operable upon movement of the piston away from the closed end of the cylinder to vpermit liquid to ow freely from the upper portion of the cylinder or reservoir into the lower portion or the cylinder as the load supporting means is raised from the frame. A special valve mechanism is provided to restrict the passage of iluid from the lower portion of the cylinder to the upper portion thereof during the descent or checking movement of the piston, and which will exert a resistance to the escape of fluid under pressure from the lower portion of the cylinder substantially proportional to the weight of the load which is imposed upon the piston, thereby enabling the load supporting means to descend at substantially the same rate of speed irrespective of the weight upon it. This is of great importance in that it prevents loss of time in the descent of the unloaded load supporting means, and also provides means for properly cushioning the descent of the load supporting means irrespective of the weight of the load.

As illustrated in Fig. 5, the piston is of tubular construction and of a size slidably to t within the cylinder 55. A head 71, which is screwed into the upper end of the piston body, is provided with a screw threaded aperture to receive a complementary screw threaded end of the piston rod 62. A series of ports 72 in the head 7l permits the liquid to flow freely into the chamber of the piston. The opposite end of the tubular body is closed by a head 78 having one or more ports 74 provided with a check valve, such as a ball 75, seated in a countersink in the head 73 and adapted to permit liquid to flow from the chamber of the piston freely into the lower portion of the cylinder as the piston is moved away from the lower head of the cylinder. The head 73 is provided with a central screw threaded aperture in which is seated a plug 76 having an enlarged head portion 77 which abuts against the head 73. The ports 78 in the head of the plug communicate with an annular groove 79 in said plug adjacent its head and a radial port or ports 80 establish communication between the groove 79 and an axial bore 81. A valve stem 82 has a reduced extension which is also screwed into the aperture in the lower head 78 and is provided with an axial port 83 which extends upwardly a considerable distance and communicates with radial ports 84. A common collar 85 is mounted upon the stem 82 adjacent to and abutting against the head. A sleeve valve 86 is slidably mounted upon the stem 82 and provided with a skirt 87 fitting and slidably mounted Aupon the collar 85 and is of suicient length to provide a space 88 between said collar and sleeve. Small ports 89 extend longitudinally through the sleeve Valve 86. Another sleeve 90 is reciprocably mounted upon the valve stem 82 and provided with a skirt 91 which ts upon the sleeve valve 86 and is of sufficient length to provide a chamber 92 therebetween. A port or ports 93 extend through the sleeve 9D and communicate with a chamber 94 with a cap 95 having radial ports 96 communicating with the chamber of the piston. A coil spring 97, which is interposed between the cap and the head 98 upon the stern 82, serves normally to force the cap and sleeves downwardly into the position illustrated in Fig. 5.

In the operation of the device the upward movement of the piston, to the right, Fig. 5, permits uid from the upper portion of the cylin der or reservoir to now freely through the port 72 in the upper piston head and the port 74` in the lower piston head into the lower portion' of the cylinder, the ball of the check valve being unseated by the fluid during such movement. This permits the piston to move upwardlywith 'freedom as the load supporting means is raised.

When the load supporting means is released from its raised position and begins to descend. the piston 6l is forced downwardly in the cylinder 55, thereby causing the valve 75 to close the port 74. Fluid from the lower portion of the cylinder is then forced through the ports 78 in the plug 76 into the annular recess 79 therein, thence through the radial port into the axial bore 81 from which it escapes into the axial bere 83, of the stem 82. If no Very heavy pressiue is imposed upon the liquid in the lower portion of the cylinder, the liquid then iiows from the axial bore 83 of the stem through the radial ports 84 into the chamber 92, thence through the port 93 of the sleeve 90 into the chamber 94 of the cap 95 and from the chamber 95 'through the ports 96 into the chamber of the piston, from which it may escape through the port 72 into the upper portion of the cylinder or reservoir. The restriction to the iiow of the liquid as it passes through the small ports and chambers above described will impose suiiicient resistance to the movement of the piston under light loads properly to cushion the descent of the load supporting means. When, howeveig'a sufliciently heavy load is imposed upon the load supporting means, the force with which the liquid is projected through the axial bore 83 in the stem 82 will cause it to iiow through the port 89 in the sleeve 86, and thereby build up a pressure in the chamber' 88 which will force the sleeve 86 longitudinally upon the stem against the resistance of the spring 97 and closes the port 84 more or less, thereby further restricting the ow of liquid from the lower portion of the cylinder to the chamber of the piston and consequently to the upper portion of the cylinder.

By employing a spring 97 of suitable compressive strength, the extent of movement of the sleeve 86 in response to the pressure built up in the chamber 88 may be so controlled as to correlate the restriction of the port 84 and consequently the resistance to the escape of fluid under pressure to the weight of the maximum load as to cause a resistance to be offered to the descent of the load substantially proportional to the weight of the load, so that the load supporting means will descend at substantially the same rate of speed irrespective of the load which is carried by the load supporting means.

f Desirably a spring 99 is interposed between the end 66 of the reservoir and the collar 100 which is xedly secured to the piston rod to force the piston rod downwardly when the load supporting means carries no load.

It will be noted that in the construction above described the piston rod is pivotally connected to the shaft 36 upon which the upper end of the rear link ymechanism is also pivoted, and that the closed lower end of the dash pot is pivotally connected to the cross girderGO'of the main frame.

By reason of this construction resistance to the descent of the platform is applied directlyto the rear end portion-of the platform which ordinarily sustains the greater portion of the load and unduestrain upon the side bars of the load supporting means `is thereby avoided. i

`It will Abe apparent that the elevating truck above described has numerous advantages over other trucks of the same type in that the front end of the truck requires less head room, inithat the rearward movement of the load supporting meansv during the raising movement thereof is produced by force imparted through a thrust member pivotally mounted upon the tongue and positioned to engage a complementary abutment in upraised position it can be readily swung out of engaging relation' to said: abutment to permit free steering of the truck. A l

By reason of the fact that the load SuppOrting means is moved rearwardly relatively to the steering mechanism during the raising of the load rsup-- porting means, the load is moved asuiiioient distance away from the steering mechanism soV that when the load supporting means Vis'locked in raised position a much wider range" of steering movement ofthe tongue is permittedwithout engagement with the load than in trucksheretofore constructed. The mechanism for looking the load supporting means in raised'position is oi a simple rigid character and maintained in locked position by the tendency of the load SuplDOr'ting mean'sto move forwardunder the load upon it. inasmuch as the compression resistance of metal exceeds the tensile strength thereof, this locking means can be relatively light. The rotation of the rotatable member or rodwhich is engaged by the shouldered end of the locking means can be easily accomplished and the locking mechanism released with a minimum eiort.

The construction of the dash pot mechanism above described is such as to avoid any possible leakage of huid which will impair the eiiiciency of the dash pot. The mechanism is of a simple construction and can be more economically manufactured than usual trucks of this type.

It will be understood .that the particular ernbodiment of the invention disclosed herein is of an illustrative character 'and is not restrictive, and that various changes in form, construction and arrangement of parts maybe made within the spirit and scope of the following claims.

Having thus described the invention, what is claimed as new, and desired to be secured by Letters Patent, is:y

l. An elevating truck comprising a main frame, load supporting means,means rfor raising said load supporting means upon movement thereof rearwardly relatively to said main frame includ- 'which is imposed f ing a tongue mounted to swing vertically and a thrust memberpivotally mounted on said tongue and operable upon vertical swinging movement of said tonguedetachablyito engage and shove said load supporting means rearwardly. Y

2. An elevating truck comprising a main frame having steering mechanism including a tongue mounted to swing vertically,` load supporting means, means for raising said load supporting means upon movement thereof rearwardly relatively tosaid steering means, ,and a thrust membei' intermediate of said steering` mechanism and said loady supporting means operable upon de# pression of said tongue from upraised position detachably to engage and then to shove said load supporting meansV rearwardly.

,3. An elevating truck comprising a main frame having steering mechanism including a tongue mounted to swing vertically, load supporting means, means ior raising Vsaid load supporting Vmeans upon movement thereof rearwardly relaf tivelyvto said steering means, and a thrust member pivotally connected to said tongue operable upon depression of said tongue from upraised position detachablyto engage and then to shove saidload supporting means rearwardly.

4. An elevating truck comprising a main frame having steering mechanism including a tongue mounted lto swing vertically, load supporting means, means for raising. said load supporting means upon movement thereof rearwardly relaf' tively to said steering means, a thrust member pivotally connected tosaid tongue operable upon depression of said tongue from upraised position detachably to engage and then to shove said load supporting means rearwardly, and means for normally positioning said thrust member toengage a complementary abutment on said load supportingY means upon depressionof said tongue from 115 upraisedposition.

5. An elevating truck comprising 'a main frame having steering mechanism including a tongue mounted to swingvertically, load' supporting means, means` for raising saidloadsupporting means upon movement thereof rearwardly relatively to said steering means, athrust member i pivotally connected to said tongue operable upon depression of said tongue from upraised position detachably toengage and then `toshove said load supportingmeans rearwardly, and resilient means normally positioning said thrust` memberto engage a complementary abutment on said load supporting means upon depression of said tonguel from upraised position and to disengage said thrust member from said abutment when the tongue is raised from depressed position.

6. An elevating truck comprising a main frame having steering mechanism including a vertical steering post having ears extending a short distance above said frame, a tongue pivotally mounted on said ears, load supporting means connected to said frame by parallel links operable upon longitudinal movement of said loadisupporting means rearwardly 'to raise the same, a thrust member pivotally mounted on said tongue below the fulcrurn thereof, and means operable when the tongue is depressed from upraised position to cause said thrust member detachably to engage a complementary abutment upon said load supporting means, whereby further depression of said tongue will shove the load supporting means rearwardly.

7. An elevating truck comprising a main frame having steering mechanism including a vertical steering post having ears extending a short distance above said frame, a tongue pivotally mounted on said ears, load supporting means connected to said frame by parallel links operable upon longitudinal movement of said load supporting means rearwardly to raise the same, a thrust member pivotally mounted on said tongue below the fulcrum thereof, and means for so supporting said thrust member when the tongue is in upraised position as to permit unimpeded rotation of said steering mechanism, and selectively operable when the tongue is swung downwardly from upraised position in a plane approximating the longitudinal axial plane of the truck to cause said thrust member detachably to engage a complementary abutment upon said load supporting means and upon continued downward swinging movement of the tongue to shove said load supporting means rearwardly.

' 8. An elevating truck comprising a main frame having steering mechanism including a vertical steering post having ears extending a short distance above said frame, a tongue pivotally mounted on said ears, load supporting means connected to said frame by parallel links operable upon longitudinal movement of said load supporting means rearwardly to raise the same, a thrust member pivotally mounted on said tongue below the fulcrum thereof, a narrow abutment on said load supporting means centrally of the width thereof, a thrust member pivotally mounted on said tongue below the fulcrum thereof of such length and so positioned as selectively to permit depression of the tongue from upraised position v in different vertical planes to cause load-lifting engagement with said abutment, or to prevent engagement of said thrust member therewith, thereby permitting free steering movement of said tongue. Y

9. An elevating truck comprising a main framer Y load supporting means, parallel links connecting tating said rotatable member to disengage said pawl therefrom by rolling contact therewith.

10. An elevating truck comprising a main frame, load supporting means, parallel links connecting said load supporting means to said frame, operable to raise said load supporting means upon movement thereof rearwardly relative to said main frame, means for locking said load supporting means in raised position before the parallel links have reached a vertical position comprising a cylindrical member rotatably mounted upon said frame, a co-operating thrust pawl pivotally mounted on said load supporting means normally resting upon said cylindrical member and having a shouldered free end portion adapted to engage and abut against said rotatable member upon approach of said parallel links to approximately vertical position, means for rotating said rotatable member in a direction to disengage the shoulder of said pawl therewith by such rotative movement, and means for rotating said rotatable member in the reverse direction.

11. An elevating truck comprising a main frame, load supporting means, and means for raising said load supporting means upon longitudinal movement thereof relatively to said load supporting means, a dash pot upwardly inclined from the horizontal having a piston pivotally connected to said load supporting means, a cylinder pivotally mounted on said frame and a reservoir extending from the upper end of said cylinder so constructed as to maintain a liquid level therein at such height as to insure complete filling of the portion of the cylinder below the piston with liquid at all degrees of inclination of said dash pot.

12. An elevating truck comprising a main frame, load supporting means, and means for raising said load supporting means upon longi tudinal movement thereofv relatively to said load supporting means, a dash pot upwardly inclined from the horizontal having a piston pivotally connected to said load supporting means, a cylinder having a closed lower end pivotally mounted upon said frame and an open upper end, a reservoir forming an extension of the upper end of said cylinder so inclined to the axis of said cylinder as to maintain a liquid level in said reservoir above said piston at all degrees of inclination of said dash pot cylinder.

DANIEL E. HENNESSY.