US2785818A

US2785818A - Stripper mechanism for lift trucks

Info

Publication number: US2785818A
Authority: US
Inventors: Amos J Mercier; George G Morin
Original assignee: MORIN
Current assignee: MORIN
Priority date: 1955-02-09
Filing date: 1955-02-09
Publication date: 1957-03-19
Anticipated expiration: 1974-03-19

Description

March 19, 1957 A. J. MERCIER ETAL 2,785,818

STRIPPER MECHANISM FOR LIFT TRUCKS Filed Feb. 9, 1955 s Sheets-Sheet 1 INVENTORS Amos J. MERCIER 8: GEORGE G. MORIN a ATTO RN EYs March 19, 1957 A. J. MERCIER ETAL STRIPPER MECHANISM FOR LIFT TRUCKS 6 Sheets-Sheet 2 INVENTORS Amos J. MERCIER &

BY GE RGE 6. Memo:

54 J 7464/ ATTORNEYS Filed Feb. 9, 1955 March 19, 1957 A. J. MERCIER ETAL STRIPPER MECHANISM FOR LIFT TRUCKS Filed Feb. 9, 1955 6 Sheets-Sheet 3 ENTORS AMOS J-MERCIER 3, Y GEORGE G-MORIN ATTORNEKS March 19, 1957 A. J. MERCIER ETAL STRIPPER MECHANISM FOR LIFT TRUCKS 6 Sheets-Sheet 4 Filed Feb. 9, 195

5 m w. mum mm wm flm N 12 .6 A E 6 m M 5 A6 Y B March 19, 1957 A. J. MEiQclER EIAL 2,785,818

STRIPPER MECHANISM FOR LIFT TRUCKS Filed Feb. 9, 1955 6 Sheets-Sheet 5 INVENTORS Amos J.MERCIER 8r GEORGE G.Mom-

ATTORNEYS March 19, 1957 A. J. MERCIER ETAL 2,785,813

STRIPPER MECHANISM FOR LIFT TRUCKS Filed Feb. 9, 1955 6 Sheets-Sheet 6 INVENTORS Amos J.MERCIER & BY GEORGE G.Mom-

ATTORNEYS United States Patent STRIPPER MECHANISM FOR LIFT TRUCKS Amos J. Mercier, Holyoke, and George G. Morin, West Springfield, Mass; said Mercier assignor to said Morin Application February 9, 1955, Serial No. 487,120

10 Claims. (Cl. 214-514) This invention relates to lift trucks and more particularly to lift trucks provided with power driven stripper mechanism. The present invention is in the nature of an improvement on the invention disclosed in our co-pending application filed June 24, 1950, Serial No. 170,124 and now Patent No. 2,709,531.

An object of the present invention is to provide a lift truck with improved stripper control mechanism which provides an increased flexibility in the use of the truck.

A further object of the present invention is to provide an improved positive and releasable means for locking a pallet to the forks which may be controlled by actuation of the pusher.

Another object of the present invention is to provide means to load heavy fiat bottom articles on article carrying forks without the aid of workers other than that of the lift truck operation, and which may also be controlled by actuation of the stripper.

Another object of my invention is to provide means whereby the stripper of a lift truck which has an automatic stripper advance mechanism, synchronized with the reverse drive of the truck, may be locked at any desired position on the forks or platform of the elevator for automatic operation to and from the selected position.

These and other objects and advantages of the present invention are more clearly developed in the following description and accompanying drawings, in which:

Fig. 1 is a side elevational view of a lift truck embodying my invention;

Fig. 2 is a front perspective view of the mechanism shown in Fig. 1, with special emphasis on the automatic drive mechanism for the article engaging stripper;

Fig. 3 is a rear perspective view of the mechanism shown in Fig. 1 except for part of the drive mechanism;

Fig. 4 is a side elevational view of the manually operable stripper drive shown in Fig. 3;

Fig. 5 is a view similar to that of Fig. 4, without the block 25 and with a dotted line view of said mechanism in an elevated position with the stripper in a proportionate forward position;

Fig. 6 is a detailed sectional view of part of the drive mechanism, especially of the clutch mechanism, the automatic clutch release and the mechanism attendant to shaft 27 for driving the drum 16;

Fig. 7 is a detailed sectional view taken substantially on line 77 of Fig. 6;

Fig. 8 is a side elevational view of the stripper and a forwardly projecting article carrying support member with a pallet mounted thereon, said stripper being in a withdrawn position, holding a pivot latch in its disengaged position;

Fig. 9 is a view similar to Fig. 8, but with the stripper being in an extended position, and said pivot latch being in an engaged position; a

Fig. 10 is a view of a sheath-like inclined locking device;

Fig. 11 is a front perspective view of the stripper, with ice its front lower wall broken away, and attendant mechanisms;

Fig. 12 is a side elevational view of a wedge block;

Fig. 13 is a side elevational view of a tilted article carrying support member (fork) engaging the underside of a crate;

Fig. 14 is a follow-up view of Fig. 13 showing the stripper in dotted lines moved up adjacent the crate and a wedge block being inserted under the crate as the crate is tilted upwardly by the aforesaid fork;

Fig. 15 shows the said fork outwardly freely advancing under the crate, while the wedge block alone is supporting the inner edge of said crate in an elevated position;

Fig. 16 is a perspective of one specie of pallet which can be used with our invention; and

Fig. 17 is a perspective of another specie of pallet which can be used with our invention.

Fig. 1 shows a power driven lift truck which has a forward and a reverse drive (not shown) and carries at the fore end of the body 1 an elevating means of any suitable form on which is mounted, for vertical reciprocation a forwardly projecting article carrying support member 2 shown in the form of forks. In the form shown in Figs. 1 and 2, the elevating means includes two sets of vertically disposed channels 3 and 4. The inner channels 3 are movable vertically under the influence of a hydraulic ram 5, and the outer channels 4 are pivoted to the truck body 1 by brackets 6, for tilting in the usual manner by hydraulic cylinder 7. A chain 8, secured at one end to a crosspiece 9 mounted on the fixed channels 4, is trained upwardly and over a sheave 10 carried on a beam 11 on the movable channels 3, and is finally trained downwardly and secured as shown in Fig. 2 to a generally U-shaped elevating bracket 12. As the channels 3 are moved up and down by the ram 5, the bracket 12 is likewise shifted up and down by the action of sheave 1t and chain 8. The carrying member 2 is mounted upon the elevating bracket 12 to be moved therewith.

An article-engaging stripper 13 including

parallel frame members

14 and 15, side members 16 and upper cross members 17 is disposed forwardly of the elevating bracket 12 and over the carrying member 2.

Fig. 1 shows one example of an automatically synchronized drive mechanism, for the stripper 13, embodying the improvement of the present invention, and the general relation of said mechanism to the rest of the truck; Figs. 2-4 show details of construction of said mechanism, as well as an independently actuated drive mechanism for the stripper 13 later described.

As best shown in Figs. 2 and 3 the elevating bracket 12 has a pair of rearwardly extending leg plates 18, and a horizontal cross-shaft 19, journaled in said plate 18, across the back of the bracket 12 and rearwardly of channels 3 and 4. Keyed to the shaft 19 adjacent the extremities thereof and inside the plates 18 are a pair of drive drums 21 and 22.

A pair of triangular frame members comprising the outer vertical sides 16 of the stripper, horizontally disposed members 24 provided with upwardly facing racks 25 (in engagement with pinion 26 keyed to shaft 19), and obliquely disposed members 27 extend rearwardly from stripper 13. Members 27 are connected, as at 28 to the lower portion of said vertical members 16, and at their rear ends to depending bracket members 29. Said triangular frame members with the stripper 13 form the horizontally forward and rearward moving stripper assembly which is mounted on sets of rollers 31 extending outwardly from the vertical side portion of the bracket 18 of the elevator 12, so that the entire stripper assembly is reciprocable on said rollers. Pinions 26 keyed to the ends of shaft 15 engage racks 25 to recipr0- cate the stripper upon rotation of the shaft.'

A driving cable 32 is attached to and wound around driver drum 2?. and the other end of said cable is attached to a drum 33, for winding thereon, which is journaled on a shaft 34 hereinafter described. A torsion spring 35 is coiled about the shaft 19 and has one end fixed to driver drum 21, the other end being anchored to a block 36 which is rotatably mounted on shaft in inward adjacent relation to driver drum 22, said spring acting as a motor spring as is hereinafter explained. Radial seats, as shown at 37, in block 36 permit said block to receive bar 38, which bar, when it is seated in the block 36 (as shown in Fig. 4) has its rotatable (unwinding) path obstructed at 39 by angled plate 41. By turning block and inserting bar 38 in selected seat 37 .for engagement by plate 41 to restrain the rotation of block 36, the tors'ion'force of spring can'be adjusted.

A bearing post 42 supports the shaft 34 on the truck body 1 (Figs. 1, 6 and 7), with the outer end of the shaft extending slightly beyond the bearing post. A sprocket wheel 43 is keyed at 44 to this outer extension of-shaft 34 and is connected by a chain 45 to a sprocket wheel 46 fixed on the axle 47 of a front truck wheel 48. A collar 49 is fixed by set screw 51 on shaft 34 to prevent lateral movement of sprocket 43 on said shaft. A one-way overrunning clutch indicated by 52 of any suitable form is provided between shaft 34 and sprocket 43. This clutch acts to couple said shaft and sprocket 43 only when the chain 45 drives the sprocket 43 in a clockwise direction as viewed in Fig. 2; i. e. when the truck is driven in reverse.

A clutch assembly generally designated by 53 (Fig. 6) is provided to releasably couple drum 33 to shaft 34, said clutch comprising a pair of tooth

clutch members

54 and 55, clutch member 54 being slidably keyed to shaft 34 and clutch member 55 being integral with drum 33. Clutch member 54 is adapted to he slid or traversed along shaft 34 to and from operative engagement with member 55 by a collar 56 having opposed rolls riding in grooves 57 formed in the clutch member 54. Collar 56 is pivotally attached to a toggle arm 58 which is slidably pinned to a toggle arm 59 which is integral with a clutch handle 61 and pivotally connected to the truck frame at 62. Spring 63, which is extended between the-outer extremities of the toggle, serves to releasably retain the toggle in clutch engaging or disengaging position. A hydraulic jack 64 is'mounted on the body of the truck, vertically beneath the knee of the toggle, so as to permit'said toggleknee to pivot below spring 63 so as to move down below dead center, the result of which is -to traverse clutch member 54 along shaft 34'into engagement with clutch member 55. The stroke of the plunger 65 of jack 64 is suflicient when elevated to engage said toggle knee and force it above the spring 63 to the position of Fig. 6 to thereby disengage the clutch.

A pipe line 66 and fiexible'hose 67 connects jack cylinder 64 with a cylinder 68 mounted on :the U-shaped elevating bracket outwardly adjacent to drum 21, having a piston rod 69' extending rearwardly .in the .path of bracket'29.

The stripper assembly may be moved forward from its relative position to the truck in Fig. 1 by engaging clutch 53 and by backing the truck. The rearward rotating sprocket 43 causes the one-way ovenrunning clutch 28 to turn clockwise in Fig. 1, which in turn causes the shaft 34, clutch member 54, clutch member 55 and drum .33 to rotate clockwise as seen in Fig. 2 so as to wind cable 32 thereon. As cable 22 pays off driver drurn21, it rotates shaft 19 and pinions 26 clockwise, thus advancing rack member 24, the sprocket gearratios and drum diameters being such that stripper '10 is thereby advanced at the same rate at which the truck is driven rearwardly. .As the stripper reaches the extreme of its advance movement (i. c. When the fore edge of the stripper .is in er slightly beyond the same vertical plane as the fore edge of article carrying member 2) bracket'29 engages the piston rod 69, and drives the latter inwardly of cylinder 68 thereby causing pressure to be exerted through the hydraulic line comprising pipe 66 and hose 67 on the piston of jack cylinder 64, thereby causing piston rod to rise so as to break the toggle and disengage clutch 53. While the shaft 19 was being revolved during the stripper 13 advance, torsion spring 35 was being wound and upon disengagement of clutch 53 and the removal of clockwise pull on cable 32, the torsion spring 35 immediately turns the shaft 1-9, its pinions 26 and the driver drums 21 and22 in a counterclockwise direction returning the stripper to its original'position and rewinding cable 32 on drum 21. As cable 32 is thus rewound on drum 21'relativelylight spring 71 (see Figs. 6 and 7) having one end fixed at 72 to the hub of drum 33 and the other end fixed to a stationary flange 73 fixed to hearing 42 by a bracket 74. This spring 71 also serves to maintain cable 32 taut as additional cable is payed ofi and taken up by .the' drum 33 inraising-and lowering of theelevator.

Figs. 3, 4.and 5 show a'second means for advancing the stripper 13 while the track is not in motion. A bydraulic cylinder 75 is mounted on the elevator, forwardly of the shaft 19. A chain 76-is attached :at one 611C110 drum 22 and wound thereon, counterclockwise as viewed in Figs. 4 and 5, said chain being trained up 'over .a sprocket 77 and attached at its other end to an .anchor pin 78 fixed to the elevator. A piston rod 79 operating in cylinder 75 has a stroke of sufiicient length so that with the sprocket 77 at its lowermost position and stripper 13 in retracted position full elevation of the piston'rod 79 will cause suificient chain .to :be payed-off drum 22 to cause drum 22, shaft 19 and pinions 26 to rotate (clock wise in Figs. 3, 4 and 5) suificiently to advance the a stripper to its 'outermost'posi-tion. -Piston rod '79 is raised by hydraulic pressure supplied through line 81, in which a valve generally shown'at 82 is installed. Said valve has a rotatable valve plug 83, provided with a'handle84-a-nd formed with a passage 85'which in position a (Fig. -4) connects line 81 with a suitable-source of hydraulic pressure not shown) and in position b connects line 8'1'to exhaust. In intermediate position 0 valve 182 looks the hydraulic fluidin cylinder 75.

The =cylinder75 with its valve controlled power line 81 and piston rod 79, sprocket 77, chain 76 and drum 22 in effect form a'second source of power for actuatingthe same driving mechanism for advancing and returning thestripper, namely, shaft 19, pinions 26, racks 25 and motor spring 35, as that through which power is applied via clutch 53 from the reverse drive of the truck. Ihis arrangement, in addition to providing means for -.unlo.adring the truck when the latter is stationary, provides in combination with the synchronized drive from ,the reverse drive of the truck a more flexible and advantageous use of the stripper when theflatter is being poweredl'from the reverse drive. When the stripper is moved forward by power supplied through cylinder 75, cable 32rnerely pays off from drum 21 and is simultaneously wound on drum 33 as a result of the action of spring 71 tending to turn said drum 33 in a clockwise direction as in Fig. 2. When the stripper is advanced by ,power supplied through clutch 53, chain 7.6 is merely payed 'oif'from drum 22 forming a fest-oon as indicated in dotted lines at 86 i in Fig. 4. In other words the power connections to the effectholds the load stationary iover thewpoint -efcdeposit While the support is withdrawn from heneath :the .load. It is obviously essential for neatzand proper tpiling at Ihestart of the discharging'operation thatzthestripper be in engagement with the rear face of the load. By'the combination of the present invention :the stripper Lean be advanced by power supplied through cylinder 75 to any position along the support 2 so as to engage the rear of a load of any horizontal dimension longitudinally of the support and the hydraulic fluid locked in the cylin- -der 75 by moving valve handle 84 to position c. From that position the stripper can be advanced to discharge position by the synchronized drive through clutch 53, chain 76 festooning below drum 22 as previously described. However, on the automatic return of the stripper from discharge position, under the power of spring 35, the retreat of the pusher is stopped at the point of initial departure since the reverse rotation of shaft 19 has taken up the festooned portion of chain 76 and the fluid locked in cylinder 75 prevents further rotation of shaft 19. Thus, once set for a load of particular size, the truck can be operated to pile loads of that size without further manipulation of, or recourse to, the valve 82.

Since power from either source is applied through shaft 19, pinions 26 and rack 25, power may be applied through cylinder 75 to aid the power supplied through the synchronized drive without interfering with the synchronism of the latter.

A further advantage of the described combination and arrangement of the two power sources for the stripper driving mechanism is in their use for controlling means for locking pallets to the lifting forks :of a truck.

As shown in Figs. 2, 8, 9 and 10 the forks 2 are fitted with channeled blocks 87 held on the forks in any suitable manner as by set screws 88. The blocks are positioned adjacent the heel of the forks, the rear edges of the blocks forming locking abutments 89. The pallet, generally indicated at 91 in Figs. 2 and 8, is there shown as having a relatively thick sheet metal top surface member 92 carried by spaced stringers 93, between which the forks 2 extend, and a sheet metal bottom member 94. The rear edge of top member 92 is bent downwardly to form a flange 95 adapted to engage over the abutments 89, as best shown in Figs. 8 and 9, when the pallet is in carrying position on the forks, thus preventing forward movement of the pallet on the forks. When a load is discharged from the pallet, and the center of gravity of the load approaches or reaches the forward edge of the pallet, the rear edge of the pallet tends to tilt upwardly disengaging the flange 95 from the abutments 89. To prevent such movement latches 96, shown in the form of channel members embracing the shanks of the forks are pivoted to the latter at 97. The latches are urged forwardly of the forks, by leaf springs 98, secured at their upper ends to either the upper ends of the latches or to the fork shanks, to position the forward lower edge of the latches over the top of the pallet adjacent the flange 95 as shown in Fig. 9, thus preventing tilting of the pallet to a degree that would disengage the flange from the abutments 89. When the stripper is in its rearmost position, as in Fig. 8, it engages the latches 96 and forces them, against the action of springs rearwardly of the rear edge of the pallet, permitting the forks to be lowered to disconnect the flange 95 and abutments 89 for withdrawal from the pallet when the latter is resting on the floor or insertion of the forks in the pallet for engagement of the flange and abutment when the forks are raised and the pallet picked up. As will be apparent the initial forward movement of the stripper in the unloading operation permits the latches to swing forward into the pallet locking position of Fig. 9. When the pallet is merely used for forming a platform for the elevator in transporting hand loaded and unloaded articles or material, the stripper may be inched forward, by power supplied through cylinder 75, sufliciently to permit the latches to swing to locking position and the stripper locked in-position by setting the valve 82 in fluid trapping position. The abutments 89 are positioned under stripper 13, when the latter is in retracted position so the blocks 76 do not materially interfere with the use of the forks in non-pallet operation, but the blocks may be removed,

by loosening set screws 88, for non-pallet operation if desired.

In the pallet shown in Fi s. 8 and 9 the overall metal sheet on plates 92 adds materially to the dead load weight of the pallet. In Fig. 17 a construction is shown which provides a lighter weight pallet having all the locking advantages of the pallet of Figs. 8 and 9. As shown in Fig. 17, the stringers 99 are notched adjacent their rear ends, as at 161 to receive a relatively narrow metal strip 192 which is provided along its rear edge with a downwardly extending flange 103 which is equivalent in form and function to the flange 70 of the pallet previously described. Strip 102 lies flush with the surface of the stringers 99 and a sheet of plywood 104 or other suitable material overlies the stringers in overlapping relation to strip 102 to form the loading surface of the pallet.

In some cases it is advantageous to pick up the pallet from either side. A pallet adapted to this manner of use is shown in Fig. 16. As there shown both ends of the stringers 105 and 106 are recessed as at 107 and 108 to receive

respective metal strips

109, 119 similar to strip 102 previously described and having respective downwardly extending

locking flanges

112 and 113. A sheet 114 similar to sheet 104 forms the load carrying surface of the pallet.

In the several forms of pallets shown the forward end portions of the stringers are relieved along their lower surface as at 115, both the forward and rear ends being so relieved in Fig. 16, and the plate 116 which forms the undersurface of the pallet of the latter figure being of a transverse width equal to the unrelieved portion of the undersurface of the stringers. The relieving of the stringers at the forward edge of the pallet permits the forks of the supporting member to be tilted prior to the removal of the load from the pallet by the pusher, thus reducing the drop of load as it is removed from the pallet to the relatively small height at the relieved end of the stringer. This is made possible by the fact that the pallet is locked to the forks at its rear edge by

flanges

76 or 103 and latches 96.

The inclusion of unsynchronized power source 75 makes possible the use and operation of the fork loading aid shown in Figs. 11 to 15 inclusive. This loading aid comprise wedge blocks 117 each having a forwardly inclined surface 118 and extending forwardly from the bottom of a vertical stem 119. Adjacent its upper end stem 119 is provided with horizontal headed pin 121. The stem 119 of the wedge blocks are inserted between

frame members

14 and 15 of the pusher with its pin engaging in vertical slots 122 formed in member 14 and having a limited vertical movement limited by the engagement of pin 121 with the bottom of slot 122, and the engagement of shoulder 123 of the wedges with the underside of the stripper 13.

The operation of the described loading aid in picking up heavy articles such as a box or crate, is shown in Figs. l3, l4- and 15. With the fork assembly tipped forwardly as shown in Fig. 13, the nose of the fork is under the article, the wedges dropping below the surface of the forks. The fork assembly is then tilted rearwardly as shown in Fig. 14 so as to elevate the near edge of the article and the stripper 13 is advanced by power supplied through cylinder 75 to bring the inclined portion of the blocks 118 beneath the raised edge of the article as is shown in dotted lines in Fig. 14. The fork of the truck is now brought to horizontal position and since the article is now supported by the Wedges the fork may be freely advanced under the article as shown in Fig. 15, with the result that the heavy article is loaded on the fork by the truck operator without assistance.

it will be apparent that cylinder 75 represents a power dnve acting on the stripper reciprocating mechanism, represented by shaft 19, pinions 26 and racks 25, through a one-way power transmission represented by sprocket reverse drive shaft 34.

77, chain 76 and drum 22 to advance the stripper; and that shaft 34, powered from the reverse drive of the truck represents a second power drive connected to the stripper reciprocating mechanism through a one-way power transmission represented by drums 21 and 33 and cable '32. It will further be seen that these respective transmissions are always connected to shaft 19 of the stripper advancing I mechanism but that power from cylinder '75 is applied to its transmission only when control valve 32 is in position a and that power is applied from shaft 34 only when clutch 53 is engaged inwhich case the stripper advancing mechanism is automatically advanced thereby, when the truck is thrown into reverse gear, at the same speed at which. the truck moves backwardly; Since the transmissions are overrunning with respect to each other power may be supplied to shaft '19 of the stripper advancing mechanism through either one or through both simultaneously. For example in case the frictional weight of the load on the load support tends to stall the reverse drive of the truck, when power is supplied therefrom to the stripper driving mechanism, additional power may be supplied from cylinder 75. The stripper is driven rearwardly by spring motor 35 which is energized by any forward movement of the stripper imparted from either power drive.

The festoon of chain 76 represents a lost motion connection in the power transmission between cylinder '75 and shaft B, the extent of the lost motion being decreased proportionally to the extent to which the transmission from cylinder 75 has overrun the transmission from the By this arrangement, when the stripper is advanced to a partially advanced position by power supplied by cylinder 75 and valve 82 is set in position to trap the fluid in cylinder 75, the festoon formed in chain 76 by completion of the advance of the pusher by power supplied from the reverse drive, represents only that part of the lost motion effective between the position obtained by the stripper when the fluid was locked in cylinder 75 and the extreme forward position of the stripper. Therefore when the stripper returns under power supplied by spring motor 35 the stripper is stopped when the lost motion represented by the partial festoon in chain 76 has been taken up, thus permitting the piling of small articles as previously described. The stripper may also be locked at the ends of the forks permitting the strip er and truck to be operated as a bulldozer to true up the position of an article on the floor or shove articles a short distance.

The provision of the pallet locking latch at the heel of the forks, 1w ated beneath the stripper and released thereby when the stripper is in its rearmost position and actuated upon the forward movement of the stripper through either of the power transmissions permits, through the interrelated operations of the latter as above described, piling or stacking operations from a pallet, when the pallet is provided with a rear downwardly extending flange or similar means for cooperation with the. latching mechanisms. The recited arrangement, however, permits the pick up and release of such pallets, in the manner previously described, when the stripper is in retracted position and also permits the full range of usual operations with conventional pallets. For non-pallet use the provision of the wedge members 317 having a limited vertical lost motion connection with the stripper permits loading of the forks by the truck operator without assistance. 7

A a result of the combination of the invention an extremely versatile lift truck is provided having greatly 8 said supporting means comprising forwardly projecting forks. and a pallet removably telescoped on the forks, a stripper member mounted on the elevating means for reciprocation over the supporting means, means for advancin the stripper, latching means adjacent the heel of the forks for engaging the rear edge portion of the pallet when in load supporting position on the forks, said latching means being held out of engagement with the pallet by the stripper when the latter is in its rearmost position on the forks and means to move the latching means into engagement with the rear edge portion of the pallet upon a predetermined extent of forward movement of the stripper to releasably lock the pallet to the forks.

2. A power driven lift truck as recited in claim 1 including means to hold the stripper against rearward moveme'nt from a predeterminedposition of advance when the stripper has been advanced at least to said predetermined position of advance.

3. A power driven lift truck as recited in claim 1, the forks being provided with vertically directed abutments and the pallet being provided at its rear edge with a downwardly directed flange engageable over said abutments when the pallet is in load carrying position on the forks and held in abutment engaging position by said latching means upon advance of the stripper.

4. A power driven lift truck as in claim 3, said abutments being located beneath the stripper when the latter is in retracted position to clear the loading surface of the forks in the absence of the pallet.

5. A power driven lift truck as recited in claim 1, the stripper advancing means includinga rotatable shaft journaled in the elevating means, a power drive for said shaft comprising an hydraulic cylinder mounted on the elevating means, a piston operating in said cylinder, a power transmission between said power drive and shaft comprising a drum fixed to said shaft, a sprocket carried by the piston and a sprocket chain trained over said sprocket and having one end fixed to the levating means and the other end wound on said drum when the piston is in retracted position, a valve means for selectively admitting hydraulic pressure to said cylinder, exhausting said cylinder. and locking the fluid in said cylinder at any position of movement of the piston, and a spring motor energized by the forward movement of the stripper and connected to said shaft to retract the stripper and rewind the chain on said drum upon the exhausting of the cylinder.

6. A power driven lift truck as in claim 5 having a second power drive for said shaft, a one-way power transmission between said second drive and said shaft to advance the stripper, the transmissions between said first and second power drives being mutually overnmning to permit both independent and simultaneous operation, and a clutch for connecting said second power drive to the reverse drive of the truck to automatically advance the stripper in synchronism with the rearward movement of the truck and at the same speed upon actuation of the reverse drive of the truck. 7

7. A power driven lift truck as in claim 1, the means for reciprocating the stripper including a rotatable shaft; two independently actuated power drives, respective one: way power transmission means, each overrunning with respect to the other, connecting said drives to said shaft to impart forward movement to the stripper, one of said drives being powered from the reverse drive of the truck, a clutch for optionally connecting said last-mentioned drive to the reverse drive of the truck toautomaticallv advance said stripper in synchronism with the rearward movement of the truck and at the same speed upon actuation of the reverse drive of the truck, the transmission of the other of said drives including a lost-motion connection, said other of said drives having means to lock its transmission in any position of its stripper advancing movement, and a' spring motor energized by any forward movement of the stripper to drive .the latter rearwardly,

spawns 8. In a power driven lift truck having a forward and reverse drive, load elevating means, a forwardly projecting article support carried by the elevating means and a stripper member mounted on the elevating means for reciprocation over the article support; mechanism for reciprocating the stripper, two independently actuated power drives, respective one-way power transmission means, each overrunning with respect to the other, connecting said drives to said mechanism to impart forward movement to the stripper, one of said drives being powered from the reverse drive of the truck, a clutch for optionally connecting said last-mentioned drive to the reverse drive of the truck to automatically advance said stripper in synchronism with the rearward movement of the truck and at the same speed upon actuation of the reverse drive of the truck, the transmission of the other of said drives including a lost-motion connection, said other of said drives having means to lock its transmission in any position of its stripper advancing movement, and a spring motor energized by any forward movement of the stripper to drive the latter rearwardly.

9. A power driven lift truck having load elevating means, article supporting means carried by said elevating means, said article supporting means comprising forward- 1y projecting fork members, a stripper member mounted for reciprocation over the forks, power means for advancing the stripper over the forks, and forwardly directed wedge members suspended from the lower edge portion of the stripper member, said wedge members having a 10 vertical lost-motion connection with the stripper sufiicient to permit movement of the inclined upper surfaces of the wedge members to and from a position in which said wedge surfaces extend above the upper surface of the forks and a position in which said wedge surfaces lie below the upper surface of the forks.

10. A power driven lift truck having load elevating means, article supporting means carried by said elevating means, said article supporting means comprising forwardly projecting fork members, a stripper member mounted on the elevating means for reciprocation over the forks, power means for advancing the stripper over the forks and forwardly directed Wedge members connected to the lower edge portion of the stripper member for movement therewith, said wedges being connected to the stripper member by pin and slot connections providing free vertical motion of the wedges relative to the forks to and from a position in which the inclined upper surface of the wedges extend above the upper surface of the forks and a position in which said wedge surfaces lie below the upper surfaces of the forks.

References Cited in the file of this patent UNITED STATES PATENTS 2,319,456 Hazen May 18, 1943 2,482,692 Quales et a1 Sept. 20, 1949 2,656,062 Thomas Oct. 20, 1953 2,707,573 Balwics May 3, 1955