US2424417A

US2424417A - Lift truck

Info

Publication number: US2424417A
Application number: US520185A
Authority: US
Inventors: Quayle George
Original assignee: Yale and Towne Manufacturing Co
Current assignee: Yale and Towne Manufacturing Co
Priority date: 1944-01-29
Filing date: 1944-01-29
Publication date: 1947-07-22
Anticipated expiration: 1964-07-22

Description

G. QUAYLE LIFT TRUCK 4 Sheets-Sheet l INVENTOR Grao).- 4, Qua-y BY wia/lt K TTORNEY July 2z, 1947.

A Filed Jan. 29, 1944 July G. QUAYLE LIFT TRUCK Filed Jan. 29, 1944 4 sneets-sheet 2 INVENisiR y .BY Geog@ w ATTORNEY G. QUAYLE LIFT TRUCK July v22, 1947.

Filed Jan. 29 1944 v 4 Sheets-Sheet 5 GV 6 a. BY 607 e ATTORNEY July 24, 1947.- G. QUA-YL.; 2,424,417

LIFT TRUCK Filed Jan. 29, 1944 i 4 Shee'tS-Sheet 4 k Q Y l 0 I n n t- 'o I f EW@ I 4" i1 6, l 'n w Tmnl g; F l k53": @i d: 7

sn s i: LI] "DIO "L2 u CO dl] S c@ bl r lNvr-:N'roR It 'y G'zorlge. Quay/Q,

ATTORNEY Patente-d July 22, 194'?Y LIFT TRUCK George Quayle, Philadelphia, Pa., assignor to The Yale & Towne Manufacturing Company, Stamford, Conn., a corporation of Connecticut Application January 29, 1944, Serial No. 520,185

21 Claims.

This invention relates to an industrial truck of the type in which an elevating platform is lifted relatively to a lifting head or main frame by lifting means actuated relatively to the lifting head. More particularly, my invention relates to a truck of the class described in which the lifting mechanism comprises mechanically actuated means carried in the lifting head and adapted to apply lifting effort to the elevating platform whereby to raise that platform relatively to the lifting head. In setting forth my invention I shall describe it as appliedto an elevating truck of the single frame type; that is, a truck in which the elevating platformis mounted at its forward end relatively to the lifting head Iby means on the lifting head, while the rear end of the elevating platform is raised through load wheels pivotally supported at that rear end and actuated through suitable mechanism extending toward the lifting head. In my Patent No. 2,274,164 I illustrate a single frame truck of the class described.

The invention of this application resides particularly in a new type of lifting mechanism and means for controlling that lifting mechanism. One important feature of my invention resides in the utilization of a novel form of lifting member secured to the elevating platform and eX- tending into position for operation by a lifting lever that is preferably the steering handle of the truck. As a further feature of this part of my invention, the lifting member is in the form of a strut that hangs downwardly from the elevating platform in substantially the steering axis of the truck for actuation by the steering and lifting handle. As still a further feature of this part of my invention, the strut is rotatable relatively to the elevating platform in the steering axis of the truck and is thereby adapted for cooperation with lifting means actuated by the steering and lifting handle in all steering positions.

A further feature of my invention resides in the use of compound lifting mechanism actuated by the steering and lifting handle, and cooperable with the lifting member or lifting strut. The arrangement of the parts is such that the strut and compound lifting mechanism cooperate in exactly the same way in all steering positions of the steering and lifting handle to elevate the platform at different speeds and under different mechanical advantages.

A still further feature of my invention resides in a very novel form of mechanism for urging the lifting member or strut secured to the elevating platform, into engagement with lifting means operated by the steering and lifting handle, when the elevating platform is in its lowered position. Through this arrangement of the parts, immediately upon lowering of the elevating platform, the operator may begin the lifting operation without performing additional acts. This is a great convenience and advantage as'will be appreciated by those skilled in the art.

A further feature of my invention resides in means for yieldingly moving the lifting member or strut away from the lifting means actuated by the steering and lifting handle, after the elevating platform is elevated to` a predetermined position. Because of this arrangement of the parts, when the elevating platform is raised to a predetermined position and held thereby holding mechanism, upward swinging movement of the steering and lifting handle will relieve the stress between the lifting means operated by the handle and the lifting member or strut of the elevating platform. The means urging the lifting member or strut away from engagement with the lifting means will then be effective to move the said lifting member away from engagement with the lifting means, This will of course contribute a free steering and lifting handle, all as is very desirable in the art.

A further important contribution of my invention resides in embodying in a single means the two features which I have just outlined. Thus, through utilization of a novel operating mechanism, preferably in the form of a spring pressed lever, the lifting member or strut of the elevating frame is urged towards the lifting means of the steering and lifting handle when the elevating platform is in its lowered position, and is urged away from the said lifting means when the elevating platform reaches a predetermined elevated position.

I have thus described generally the main features of my invention in order that a better understanding of the relation of my invention to the prior art may be had. There are of course additional valuable features inherent in my invention that I have not, up to this point, outlined, because those features will best be understood from the specific disclosure that follows. Naturally, I consider my contribution to the art to be of considerable breadth, and I shall solicit the grant of patent claims that will prevent the appropriation of my invention by those skilled in the art in forms varying mechanically from the particular form of my invention hereinafter set forth.

For a detailed description of my invention I shall refer to the drawings whereinV Fig. 1 is an elevation of a truck to which my invention is shown applied. Fig. 2 is a vertical partial section through the front end of the truck showing the elevating platform lowered. Fig. 3 is a View similar to Fig. 2 but illustrating the elevating platform in its fully elevated position. Fig. 4 is a View showing the parts of Fig. 2 in positions illustrating the manner in which a free lifting handle is obtained. Figs. 5 6 and 7 are respectively iigures taken along lines 5 5, Elfand 'i-'l of Fig. 2.

I shall nowrefer more particularly to the drawings to describe the specific structure of the truck therein shown as embodying my invention. In describing the structure of the truck I shall refer to the parts by the specific means. I have chosen for them, rather than by generic terms, but those skilled in the art will readily appreciate that the parts of my invention may be varied widely while operating to yield the action that is the contribution of my invention.

Referring rst to Fig. 1, I show there a single frame truck comprising an elevating platform la and a lifting head designated generally by reference numeralY Il, there being several reference numerals Il applied, to the lifting head in order to indicate better its outline. The forward end of the elevating platform lil is formed with a vertical standard I2 as is best shown in Figs. 1, 2 and 3, the standard being welded to the elevating platform. or otherwise secured as manufacturing technique may make desirable. The upper end of the standard l2, as best seen in Figs. 2 and. 5, has bearings at L3 and lllV at each side thereof for mounting a, pair of shafts l5. Pivotally supported on these shafts l5 are parallel linksv liithat` are welded or otherwise secured to a sleeve I l. Ijhe sleeveY I'il is in turn mounted through suitable bushings about a shaft I8 supported in bearings I9Y formed at the upper end of the lifting head I.I.

The forward end of the elevating platform lil, immediately below the standard l2, supports a shaft 2liv on bearings 2|. On the shaft 2U are mountedopposed links 22 connected by a sleeve a, rlfheselinksaresupported for pivotal movement, through sleeve 23a about shaft 23 mounted on the lower extensionY 24 of. the lifting head. A pair of rods 2.5 arepivoted at 25a to the opposed links 22j,- therods extending to the rear of the elevating platformwhere they are pivoted at 25 to links 2 1. The links 2l are in turn supported on shaftllV carried by the elevating platform I, and have mounted thereon rear lifting wheels 29. It is now obvious that as the forward end of the elevating platform l moves upwardly relatively to the lifting head about lower links 22 and upper links I6., the rear wheels 29 will be moved downwardly by rods 25 and links 21 to raise simultaneously the rear end of the elevating platform. Theparticular construction of the elevating platformA andliftinghead thusfar described is not per se the invention to be claimed in this application, but is set forth here merely to illustrate one type of truck with which my invention may cooperate.

For. maintaining the elevating platform in any elevatedposition to which it is moved, I utilize a hydraulic holding mechanism designated generally by reference numeral 30 in Figs. 2, 3 and 5. The-cylinder of this hydraulic holding mechanisin. is pivoted on shaft 3l relatively to the lifting head, while its ram or piston is formed.

with a, ballportion 32tting against a rounded surface 33a of a bracket 33 that is integral With the fprwardA standard l2 of the elevating plat- 4 form. The piston of the hydraulic lifting mechanism is designated by reference numeral 36, and extends upwardly through the ball portion 32 and above the plate 35 of the standard I2, whereby to support for rotation relatively thereto a handle S5.

The handle 36 has secured thereto one end 3'! of a spring 38, (Fig. 2) the other end being held xed to the plate 35 by a stud 39. The handle 36 has also secured thereto the square end 40 of a valve stem 1H that is in threaded engagement at l2 with a block fixed to the piston 3d. Those skilled in the art will appreciate that the spring 38 holds the handle S in that position in which the head l2 of the valve stem 4i prevents the ilow of fluid as is required for a lowering of the platform. When it is desired to lower the platform from any elevated position, the handle 3S is rotated against the pressure of spring 38 and rotates therewith the valve stem All. rlhevvalve stem 4l, because of its screw `Jthreaded engagement at 45a with the block 43 (the elevating platform may be lowered. The

construction and operation of the hydraulic holding mechanism is herein illustrated because it is required in a truck of the class described. It does not however form part of my invention herein claimed.

The bracket 33 secured to the elevating platform standard I2 extends forwardly and terminates at 5E] in a vertical bearing 5l for a strut support 52. Pivoted to the strut support 52 at 53 is a lifting member that I choose to call a lifting strut, here designated by reference numeral Sli. A rod 55 extends through ear 56 formed on the strut, the said rod being utilized for moving the strut as is hereinafter set forth. Formed also as part of the strut 54 are a pair of ears 5'! best shown in Fig. 7, between which extends the shaft 58. The function of the shaft 58 will be explained shortly.

The forward end of the lifting head Il is adapted to support what is termed a steering head. As shown in the drawings, this steering head comprises a main casting `6i) having a sleeve extension Si which through a bushing 62 is mounted for rotation in the cylindrical extension 63 of the lifting head il. Those skilled in the art will of course appreciate that the sleeve El through a bearing block 64 supports the forward steering wheels S in a manner well known in the art. Formed as an integral part of block Ell, andV therefore rotatable with 4the steering head. is a foot support F. This foot support is useful to present a surface relatively to which the operator may brace himself when lifting the load in all steering positions of the steering head.

The steering head casting Si) is formed with bearings for supporting the shaft G5 on which is mounted. for pivotal rotation the casting- 65 forming part of the steering and lifting handle assembly, designated by reference numeral 6l. The casting 66' carries a pair of lift pins 6B and 69 adapted to be applied sequentially to the surfaces 'l0 and 'H of the lifting strut 54. It will of course be appreciated that through the pin 53 cooperating with surface 'l0 of the lifting strut 54 the steering and lifting handle assembly will elevate the platform lll at a comparatively high speed. When the pin B9 contacts the surface 'H of the strut 5A during the latter part of the elevating operation, as illustrated in Fig.

3, the lifting will be at a lower rate of speed but the mechanical advantage will of course be greater so that the lifting operation will be easier.

What I term a connecting or control lever, is designated by reference numeral 15, and is pivoted at 16 on the lifting head. A spring 11 is secured at 18 to the lifting head and at 19 to the lever 15, and tends to rotate the said lever in a counterclockwise direction about the shaft 16. The lever 15 extends upwardly at one side of its bearing on shaft 16 so as to lie between the ears 51 of the lifting strut 54 for cooperation with shaft 58. Surface 80 of the said lever 15 is adapted for cooperation with a surface 8| of the lifting strut, as will be made apparent presently.

When the elevating platform is in its lower position of Fig. 2, the spring 11 rotates the lever 15 so that the surface 80 thereof presses against the surface 8| of the strut A5f! and brings the surface 10 of the said strut against lift pin B3. It may therefore be said that when the elevating platform is in its lowered position, it is the function of the lever to maintain the strut 54 in lifting engagement with the lift pin 68. With the parts in the position of Fig. 2, the operator may place his foot against the rod 55 and move the strut clockwise about its pivot 53 and against the force of the spring 11 so as to release lift pin 53 from the strut surface 1U. This will contribute a free handle in the event the operator does not wish to lift the platform, but merely Wishes to move the truck.

With the parts in the position of Fig. 2, downward swinging movement of the handle assembly B1 acts rst through the lift pin 68 and then through the lift pin E9 to bring the parts into the position of Fig. 3. In that gure, it will be noted that the surface 15a of the lever 15 is against the shaft 53 of the strut 54. It is obvious therefore, that the lever 15 is through the shaft 58 urging the strut 54 so as to bring its surface 1l away from engagement with lift pin 69. With the parts in the position of Fig. 3, should the steering and lifting handle assembly 51 be swung upwardly, the strut 54 will immediately move clockwise due to the relieving of the stress at '69, 1|, and a free lifting handle will result. Of course, if thereafter the operator wishes to lower the elevating platform, he rwill operate the valve mechanism of the hydraulic holding mechanism through handle 35 as was already explained. The lowering of the elevating platform and the strut 54 therewith, will act to bring the strut 54 into that relation to the lever 15 that is illustrated in Fig. 2. This will effect the positioning of the strut 54 so that upward swinging movement of the steering and lifting handle assembly 61 will automatically bring lifting pin 68 into engagement with the surface 1. Thereafter, the lifting operation may readily be repeated.

In Fig. 4, there is illustrated in dash and dot lines the critical point at which the lever 15 ceases to function as a means for bringing the lifting strut 54 into engagement with the lift pin 68 and functions as a means tending to withdraw the strut from that engagement. Thus, it lwill be seen in dash and dot lines in Fig. 4, that the lifting strut -54 has moved so as to bring its surface 8| above the surface 80 of the lever 15. On the other hand, stub shaft -58 has been moved opposite the hump 15b of the lever 15 so that the said lever tends to rotate the strut '54 from its dash and dot line position to its full line position.

. 6 This the strut will do as soon as pressure is relieved between it and the liftlpin 68.

With the elevating platform in the position of Fig. 4, and with the strut in its full line position in that figure, it is sometimes desirable to raise the elevating platform further. The operator then merely can actuate the rod 55 to move the strut into its dash and dot line position for engagement with lift pin 68. The downward swinging movement of the steering and lifting handle assembly 51 will then eifect the completion of the lifting operation of the platform.

I believe that the construction and mode of operation of my invention will now be fully understood.

' I now claim:

l. In a truck of the class described, a lifting head, a steering head rotatable on said lifting head, an elevtaing platform, means mounting said elevating Vplatform for elevating movement relatively to said lifting head, a part of said elevating platform overhanging a part of said lifting head and extending into the axis of rotation of said steering head, a lifting strut pivoted on said overhanging part and extending downwardly toward said lifting head in said axis of rotation, a lifting lever pivoted on said lifting head for vertical swinging movement, thrust means on said lifting lever whereby said lifting lever applies lifting thrust to said lifting strut, and means yieldingly moving said thrust means and lifting strut into engagement when said lifting lever is in a substantially vertical position, said strut'being movable against the pressure of said yielding means to allow free downward swinging of said steering lever without lifting movement of said elevating platform.

2. In a truck of the class described, a lifting head, an elevating platform, means mounting said elevating platform for elevating movement relatively to said lifting head, a part of said elevating platform overhanging a part of said lifting head, a lifting strut pivoted on said overhanging part and hanging downwardly o-n its pivot mounting toward said lifting head, a lifting lever pivoted on said lifting head for vertical swinging movement, thrust means movable with said lifting lever and separate from said strut for engaging a surface on said strut and for applying lifting thrust thereto to elevate said elevating platform, and means yieldingly urging said strut for rotation on its pivot toward engagement with said thrust means when said elevating platform is in its lowered position.

'3. In a truck of fthe class described, la lifting head, an elevating platform, means mounting said elevating platform for elevating movement relatively to said lifting head, a part of said elevating platform overhanging a part of said lifting head, a lifting strut pivoted on said overhanging part and extending downwardly toward said lifrting head, a lifting lever pivoted on said lifting head for vertical swinging movement, thrust means movable with said lifting lever for engaging said strut and for applying lifting thrust thereto to elevate said elevating platform, and means yieldingly urging said strut toward engagement with said thrust means when said elevating platform is in its lowered position and urging said strut away from said thrust means when said elevating platform is elevated above a predetermined position.

4. In a truck of the class described, a lifting head, an elevating platform, means mounting said elevating platform for elevating movement relatively to said lifting head, a partv of said elevating platform overhanging a part of said lifting head, a lifting strut pivoted on said overhanging part andl extending downwardly toward said lifting head, a lifting lever pivoted on said lifting head for vertical swinging movement, thrust means movable with said lifting lever for engaging said strut and for applying lifting thrust thereto to elevate said elevating platform, and means yieldingly urging said strut toward engagement with said thrust means when said elevating platform is in its lowered position and urging said strut away from said thrust means when said elevating platform is elevated above a predetermined position, the thrust developed between said thrust means and said strut holding them in engagement untilV said thrust is relieved as at the end of the lifting stroke of the lifting lever. y

5. In a truck of the class described, a lifting head, an elevating platform, means mounting said elevating platform for elevating movement relatively to said lifting head, a part of said elevating platform overhanging a part of said lifting head, a lifting strut pivoted on said overhanging part and extending downwardly toward said lifting head, Ia lifting lever pivoted on said lifting head for vertical swinging movement, thrust means movable with said lifting lever for engaging said strut and for applying lifting thrust thereto to elevate said elevating platform, a pivoted lever spring pressed yieldingly for rotation about its pivot and' relativenT to said strut, a portion of said lever at one side of its pivot contacting said strut when said elevating platform is in its lowered position, and a portion of said lever at the other side of said pivot contacting the strut when said elevating platform is elevated.

6. In a, truck of the class described, a lifting head, an elevating platform, means mounting said elevating platform for elevating movement relatively Ito said lifting head, a part of said elevating platform overhanging a part of said lifting head, a lifting strut pivoted on said overhanging part and extending downwardly toward said lifting head, a lifting lever pivoted on said' lifting head for vertical swinging movement, thrust means movable with said lifting lever for engaging said strut and for applying lifting thrust thereto'to elevate said elevating platform, a lever pivoted on said lifting head and spring rotated relatively to said strut, a portion of said le'ver'at one side of its pivot contacting said strut when said elevating platform is in its lowered position whereby to press said strut toward said thrust means, and a portion of said lever at the other -side of said pivot contacting said strut when said elevating platform is raised whereby to press said strut away from said Lthrust means.

7. InA a truck of the class described, a -lifting head, an elevating platform, means mounting said elevating platform for elevating movement relatively to said lifting` head, a pant of said elevating platform overhanging a part of said lifting head, a lifting strut, a support for said lifting strut rotatable in a vertical axis on said overnanging part of the elevating platform, means pivotally mounting said strut on said support with said strut extending vertically downwardly toward said lifting head, a lifting lever pivoted on said lifting head for vertical swinging movement, and thrust means whereby said'lifting lever applies lifting thrust to said lifting strut..

8. In a truck of the class described, a lifting head, an elevating platform, means mounting' saidelevating platform for elevating movement relatively to said lifting head, a steering head rotatable on said lifting head, a part of said elevating platform overlranging a part of said lifting head, a lifting strut, a support for said strut rotatably mounted on said overhanging part of said elevating platform in the steering axis of said steering head, means pivotally mounting said strut on said support with said strut hanging downwardly substantially in the steering axis, a lifting and steering handle pivoted on said steering head for vertical swinging movement, and thrust means whereby said handle applies lifting thrust toy said lifting strut.

9. In a truck of the class described, a lifting head, an elevating platform, means mounting said elevating platform for elevating movement relatively to said lifting head, a steering head rotatable on said lifting head, a lifting strut mounted on said elevating platform and depending downwardly therefrom toward said steering head substantially in the steering axis of said steering head, a steering and lifting handle pivoted on said lifting head for vertical swinging motion, a part secured on said steering and lifting handle for engaging said strut to impart vertical lift thereto and to said elevating platform, spring pressed means mounted for movement on said steering head and adapted to urge said strut toward engagement with said handle part when said elevating platform is lowered, said spring pressed means urging said strut out of engagement with said handle surface when said elevating platform and strut are raised to a predetermined position.

l0. In a truck of the class described, a lifting head, an elevating platform, means mounting said elevating platform for elevating movement relatively to said lifting head, a steering head rotatable on said lifting head, a lifting strut mounted for rotation on said elevating platform in the steering axis of said steering head and depending downwardly therefrom toward said steering head substantially in the steering axis of said steering head, a steering and lifting handle pivoted on said lifting head for vertical swinging motion, thrust means on said steering and lifting handle for engaging said strut to impart vertical lift thereto and to said elevating platform, said strut being rotatable with said steering and lifting handle into all steering positions of said steering and lifting handle, spring pressed means mounted for movement on said steering head and adapted to urge said strut toward engagement with said handle thrust means when said elevating platform is lowered, said spring pressed means urging said struct out of engagement with said handle part when said elevating platform is raised to a predetermined position.

l1. In a truck of the class described, a lifting head, an elevating platform, means mounting said elevating platform for elevating movement relatively to said lifting head, a steering head rotatable on said lifting head, a lifting strut mounted for rotation on said elevating platform in the steering axis of said steering head and depending downwardly therefrom toward said steering head substantially in the steering axis of said steering head, a steering and lifting handle pivoted on said lifting head for vertical swinging motion, thrust means on said steering and lifting handle for engaging said strut to impart vertical lift thereto and to said elevating platform, means whereby said strut is rotatable with said steering and lifting handle into all steering positions of said steering and lifting handle, spring pressed means mounted for movement on said steering head and adapted to urge said strut toward engagement with said handle thrust means when said elevating platform is lowered, said spring pressed means urging said strut out of engagee ment with said handle part when said elevating platform is raised to a predetermined position.

12. In a truck of the class described, a lifting head, an elevating platform, means mounting said elevating platform for elevating movement relatively to said lifting head, a steering head rotatable on said lifting head, a lifting strut, means mounting said strut for rotation on said elevating platform in the steering axis of said steering head and for p-ivotal movement on a horizontal axis, said strut hanging downwardly from its mounting means toward said steering head substantially in the steering axis of said steering head, a steering and lifting handle pivoted on said lifting head for vertical swinging motion, thrust means integral with said steering lever and separate from said strut whereby said steering and lifting handle engages a surface of said strut to impart vertical lift thereto and to said elevating platform, and said thrust means through said surface rotating said strut on its mounting means whereby to actuate said strut in all steering positions.

` 13. In a truck of the class described, a lifting head, an elevating platform, means mounting said elevating platform for elevating movement relatively to said lifting head, a lifting lever piv oted on said lifting head and adapted for vertical swinging movement, thrust means movable by said lifting lever7 lift means secured to said elevating platform adapted to engage and to be actuated by said thrust means, and means yieldingly urging said lift means and thrust means into engagement when said elevating platform is in its lowered position, and urging said thrust means and lift means out of engagement when said elevating platform is elevated.

1.4. In a truck of the class described, a lifting head, an elevating platform, means mounting said elevating platform for elevating movement relatively to said lifting head, a lifting lever pivoted on said lifting head and adapted for vertical swinging movement, thrust means movable by said lifting lever, lift means secured to said f elevating platform adapted to engage and to be actuated by said thrust means to lift said elevating platform, and means mounted on said lifting head yieldingly urging said thrust means and said lift means into engagement when said elevating platform is in its lowered position, and urging said thrust means and lift means out of engagement when said elevating platform is elevated.

15. In a truck of the class described, a lifting head, an elevating platform, means mounting said elevating platform for elevating movement relatively to said lifting head, a lifting lever pivoted on said lifting head and adapted for vertical swinging movement, thrust means movable by said lifting lever, lift means secured to said elevating platform adapted to engage and to be actuated by said thrust means to lift Said elevating platform, a lever pivoted on said lifting head, a spring rotating said lever on its pivot and rela tively to said lift means, one part of said lever contacting said lift means when said elevating `platform is lowered whereby to urge said lift means toward said thrust means, and a second portion of said lever contacting said lift means when said elevating platform is raised whereby to urge said lift means out of engagement with said thrust means.

16. In a truck of the class described, a lifting head, an elevating platform, means' mounting said elevating platform for elevating movement relatively to said lifting head, a part of said elevating platform overhanging a part of said lifting head, a lifting strut pivoted o-n said overhanging part and extending downwardly toward said lifting head, a lifting lever pivoted on said lifting head for vertical swinging movement, and a pair of pins carried by said lifting lever for engaging said strut sequentially whereby to impart thrust thereto as said lever swings vertically downwardly.

l'7. In a truck of the class described, a lifting head, an elevating platform, means mounting said elevating platform for elevating movement relatively to said lifting head, a part of said elevating platform overhanging a `part of said lifting head, a lifting strut pivoted on said overhanging part and extending downwardly toward said lifting head, a lifting lever pivoted on said lifting head for vertical swinging movement, a pair of pins carried by said lifting lever for engaging said strut sequentially whereby .to impart thrust thereto as said lever swings vertically downwardly, and spring pressed means yieldingly urging said strut against one of said pins when said elevating platform is-in its lowered position, and away from said pins when said elevating platform is raised to a predetermined position.

18. In a truck of the class described, a lifting head, an elevating platform, means mounting said elevating platform for elevating movement relatively to said lifting head, a lifting lever pivoted on said lifting head and adapted for vertical swinging movement, lift imparting means movable by said lifting lever, lift means engaged by said lift imparting means for lifting said elevating platform, yielding means positioned relatively to said lift imparting means and lift means when said elevating platform is lowered whereby to urge said lift imparting means and lift means into engagement, and said yielding means being positioned relatively to said lift imparting means and lift means when said elevating platform is raised to urge said lift imparting means and lift means out of engagement.

19. In a truck of the class described, a lifting head, an elevating platform, means mounting said elevating platform for elevating movement relatively to said lifting head, a lifting lever pivoted on said lifting head and adapted for vertical swinging movement, lift imparting means connected to and movable by said lifting lever, lift means connected to and movable with said elevating platform and adapted for actuation by said lift imparting means for lifting said elevating platform, yielding means positioned relatively to said lift imparting means and lift means when said elevating platform is lowered whereby to urge said lift imparting means and lift means into engagement, and said yielding means being positioned relatively to said lift imparting means and lift means when said elevating platform is raised to urge said lift imparting means and lift means out of engagement.

20. In a truck of the class described, a lifting head, an elevating platform, means mounting saidelevating platform for elevating movement relatively to said lifting head, a lifting lever pivoted on said lifting yhead and adapted for vertical swinging movement, lift imparting means movable by said lifting lever,lift means engaged by said lift imparting means for lifting said elevating platform, yielding means adapted to urge said lift imparting means and lift means into engagement when said elevating platform is lowered, and to urge said lift imparting means and lift means out, of engagement when said elevating platform is raised.

21. In a truck of the class described, a lifting head, an elevating platform, means mounting said elevating platform for elevating movement relatively to said lifting head, a lifting lever pivoted on said lifting head and adapted for vertical swinging movement, thrust means movable by said lifting lever, lift means secured to said elevating platform adapted to engage and to be actuated by said thrust means, yielding means positioned relatively to said lift means and thrust means when said elevating platform is lowered whereby to urge said lift means and thrust means into engagement, and said yielding means being positioned relatively to said lift means and thrust means when said elevating platform is raised to urge said lift means and thrust means out of engagement.

GEORGE QUAYLE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS