US2598151A - Lift truck - Google Patents

Description

L mi?? WJ si N. WARSHAW LIFT TRUCK May 27, 1952 Filed Sept. 29, 1949 Patented May 27, 1952 This' invention? pertains to lift trucks #such asf are -'commnly vv'employed in WarehousesAx andi-fac# toriesjfrfmoving material from 'one'- locatin tol another: To facilitate V`the `transfer 'of certaintypes' 'of material, for example boxes or caitons';v it is fusual to stack such articles upon/1a portable platform oripallet, andpreparatory to movY` lng ithe 'stacked articles, the lforkfor li-ft 'armfof the. trucklwhen in 'normal load-'receivinglposition' isfinsrted beneath the platform having'tlie` articles-"stacked vthereon and is then-raised;v and holds the platform elevated above theil'oorwhile the trucks vis-"rnoved tothe Ydelivery point. Pallets 'of the socalled'single face type comprise `a hori zontal platform'provided with short legs 'orequivalent elements ffor holding it spaced labove the floor i-sufli'cientlyvto admit the fork or lift arm of the truck beneath it. Pallets ofthe `so-called double sface type have two horizontalplatforms vertically:spacedv apart to -admit the fork or lift arm of the truck between the platforms: Usually eachV platfcfarm'v comprises av plurality of trans'- verselyextendingplanks,` some ofthe planks of the lower platform being spaced'ifarenough apart torpermit thelfoldable lifting wheel of theffork orY lift 'arm to project down betweenthemso as tonen-tact the floor.'

While" pallets of either the single face or doubleface type are supposed to come in stand-- arddimensions, these 'dimensions often'vary, particularly inathe vertical height of thelupper plat-` formfromvthe floor or-the vertical height of the upperfand lower platforms with relation to-each other. Because of this situation the problem; often encountered that with prior art lift trucks in fwhichthelevel of the normal loadlreceiving position-of the' lift arm is fixed' at the rtime'- ofmanufacture; it isextremely'difcult if not'in'i-` possible to introduce the Y lift. arm Y beneath' the upper platform of the single face pallet'orbetween the upper and lower platforms o'f"doubl`e`^' face.,pa1lets )Without `avlaborioii'sv change-Sin?- the relationshipbetween-'the level of the normal load;Y rscevingfposition ofthe-lift armena tne'frespea tivegferticalfheights-ofnthepplatfornis.L

`".fl'iefp11i/ncipal object of -th'efpres'ent invention-ist obviate fthe aforesaid fdiiiicultyi of`-'p'rior`ary li'fti trucks by providing a lift truck of the character described wherein `the height'of'theffork or lift arm; v*when rin its]l normal load-receiving position,` may; bev conveniently and expeditiouslyvaried. Afzfurther objectY is Ito provide an' improved lift' truckfwhichv4 isfeasy-fto. operaie-,fv lig-htm weight"andz of'rugged; vdurableconstruetinl Other and fur?- horizontal'-section.v l

Referring to the drawngsfthe numerall ides-i ign'ates the maincarriageof 5 the A*truck *and the numeral-22 'indicates ftheflift `arnif, pickup a'r-nilol forli. The carriage I comprises la hollow; rigid' boxllk'ebody or chassis-i3 made Vfrom fabricated steel plates Welded together, and'is 'providedv/ith bearii'igs' A for a`v verticalisteering post fhavingf aiforked lower Tend having bearings for- "a horizontal shaft whichcarries 'apair of"supp`o rting and steering lWheels "4; The -uppergend'of the steer= ingr Lpest-'is provided with a horizontal lpin which receives Vthe 'forked,"lowervv end i of the steering tongue 15T provided Withfa handle' H'at its upper" end The specic'detailsof'the steeringjpost'and tongue form* ndpar-t'of the present inventiorffand need not bey further described, thesepartsbeingiv more/'or less conventional in devices offthistypei Thev body or chassis A3' of the tr rcarri'a'ge" supprts the vertically` movable motorhousin'gjlwhich V-is Aconnected tor the vchassis `3fbyfmeans--of parallel links fand 9' arranged Vat""eau :h side; of the-chassis. Within the housing I'r there lsarl-f ranged Vai motor vdevice I 0, preferably a convenetional hydraulicf motor comprisinginner and4l` outer-telescoping partsintercom'necti'ng4 the house ingl 6' and chassis 3.V The upper"oftherelatively movable motorpartsis provided with-ja transverse," pin I2 (Figzl) bymeanslof'fwhich it ispivotallyfv connected to the upper part'of lthe motorhou's ing-'6 A suitablepump; withirf-'the upper pa'rttofjI the: motorf-housing', actua-ble` by the handle I 3) provides-for'ficin'g lpressure fi'uidlinto 'the motri sofas to'eipand *the latter 'vertically andi thus' to? raise the housing 16 relatively to the-fcliassi's'3fr 'Ihe'li'ft` arm orv fork'- 2 com-prises parallel "rigid load-'supporting members I 4l and; I5-f (Figj 2)" unitedj--at their-forward' ends by' the "transverse memb'e' I6: The parts'l 4; I5 :and 'I6"are forije'd' of fal` ricated [metal plates having h'oriz'ontaljupj'- perisurfaces' lying in' th'e same plane.' Eacl'f o'fthe parts `I4' :and I5' has' vertical vstifl'enirlg"'flarfgesl ati its 'opposite sides, thus forming 'a shallow)invertedj bo'xllik'ej structure. The parts `I 4 landl 5 have in.'-V

accenti 3 together with the transverse member I6, are rigidly welded to the motor housing i6.

The rear supporting wheels I9 are mounted on shafts I8 carried by lever arms 4U pivotally secured at 4I to the parts Il of the lift arm. The levers 4D have forwardly extending arms 42 which are pivotally connected to the lower ends of rods 43 which are urged downwardly by springs 44. These rods are screw threaded at 45 at their upper ends to receive hand wheels 4E having threaded axial bores. Normally, when the lift arm is in the load-receiving position it is unsupported rearwardly of the wheels I9, the lift arm, pickup arm or fork 2 thus being in the nature of a cantilever supported at one end only and being free from contact with the ground or door rearwardly of the wheels IS except when actually supporting the load. The weight of the chassis and housing 5 (located forwardly of the wheel i9) is sufficient to sustain the unsupported portion of the lift arm inload-receiving position. The unsupported portion of the lift arm, between the wheel I9 and the free end of the arm, preferably should approximate or exceed the length of the pallet with which the truck is to be used.

Preferably, the rear free ends of the members I4 and I5 taper horizontally, as shown at 29, and their extreme rear ends also taper vertically, as shown at 2I, in order to facilitate the introduction of the free ends of these members into the interior space of the pallet.

Each of these members i4 and i5 is provided near its free, rear end with a lift wheel assembly comprising a rigid frame having an arm 22 provided with a horizontally elongate tubular bearing member 23 at its forward end. The tubular bearing 23 is pivotally supported by a horizontal shaft 24 which is fixed at its opposite ends in the vertical flanges of the member I4 or I5 respectively. The rear end of each lifting wheel assembly is provided with bearings for a shaft 25 which carries a pair of wheels or rolls 22. The frame of each lift wheel assembly also comprises a' rigid forward extending arm 27 which diverges downwardly from the arm 22, the arm 21 being provided with a bearing 28 at its forward end which receives a pin 29 (Fig. 1). A fork 3G is pivoted on this pin 29. This fork 3! is fixed to the rear end of an actuating rod 3| whose forward end is pivotally connected by a pin 32 to a rigid, upwardly directed rearward extension 9a (Fig. l) of the lower link 9 by means of which the motor housing 6 is connected to the chassis. A collar 34, fixed on the rod 3I, forms an abutment for one end of a compression spring 33 whose other end bears against a fixed abutment 35 within the respectlve member I 4 or I5. The spring 33 tends to push the pin 29 rearwardly and thus to swing the foldable lift wheel assembly upwardly to the normal position shown'in Figi. To accommodate the wheels or rolls 26, when the lift wheel assembly is folded, the horizontal platform of each of the parts I4 and I5 is provided with a transverse opening 36.

The load-receiving pallet P (Fig. l) is here illustrated as of the double-face type having the upper load-receiving platform T usually made of heavy boards or planks, and the lower platform comprising horizontally spaced, transversely extending lower members B. Usually these lower members B are boards of approximately or slightly less than one inch in thickness. By rotating the hand wheels 46 to the left or right. the rods 43 may be moved upwardly or downwardly, respectively, thus swinging the arms 40 downwardly or upwardly respectively and thereby elevating or lowering the lift arm so as to adjust the height of the free end of the lift arm, when in its normal load-receiving position, so that the lowermost element of the wheel 26 is at a level to freely clear the upper face of the lower member B of the pallet and the upper surface of the lift arm 2 is at a level to freely clear the lower face of the upper load-receiving platform T of the pallet.

In introducing the lift arm into the pallet, the parts are rst arranged as shown in Fig. l, the lift wheel assembly being folded up. The truck is then moved rearwardly in the direction of the arrow (Fig. l) and, as it moves rearwardly, the rear end of the arm 2 enters the interior space of the pallet, thefolded up wheel 26 entering this space without contacting the forward edge of the pallet member B. The movement of the truck continues rearwardly until the wheel I9 comes into contact with the forward edge of the part B of the pallet, thus indicating to the operator that the arm has been fully entered into the pallet. The operator now actuates the pump handle I3, thus causing the fluid motor I0 to lift the housing E and the lift arm 2 relatively to the chassis. Concomitantly with this movement and by reason of the upward swing of the link 9, the rod 3I is pulled forwardly, thus swinging the lift wheel assembly downwardly so that the wheel 26 contacts the floor and then assists in raising and supporting the free rear end of the lift arm. The rising lift arm is thus brought into contact with the under surface of the platform T and as the lift arm continues to rise, the entire pallet with its superposed load is lifted. The operator now ceases to actuate the pump handle and, grasping the handle H of the steering tongue, swings the latter downwardly and by means of the tongue pulls the truck to the desired point for unloading. A valve, conventional in devices of this type,v is now actuated so as to release the pressure fluid from the motor, thus permitting the lift arm to descend until the pallet rests upon the floor or ground. During this time the foldable lift wheel assembly moves up, assisted by spring 33, to its initial position, as shown in Fig. 1. By moving the truck forwardly it is readily disengaged from the pallet, the wheels 26 passing over the part B of the pallet without substantial contact with said parts so that the disengagement of the truck from the pallet is readily accomplished without damage to the pallet and without putting undue strain on the truck or requiring undue effort on the part of the user. i

When the truck is empty and resting upon the large front wheels 4 and the auxiliary supporting wheels I9, as illustrated in Fig. l, the effective wheel base is quite short, thus permitting the truck to be turned completely around in a very small space, for example in any normal aisle where the truck would be used.

While a desirable embodiment of the invention has been illustrated by way of example, together with certain suggested modifications, it is to be understood that the invention isbroadly inclusive of any and all arrangements falling within the terms of the appended claims.

I claim: i

1. A lift truck comprising a chassis, a motor housing, parallel links connecting the housing to the chassis whereby the housing may be raised and lowered relatively to the chassis,a motor device within the housing operative to raise and lower the housing, a lift arm rigidly fixed at its forward end to the housing, and movable up. and

down with the latter. a supporting wheel for the housing located adjacent to the junction of the arm and housing, said wheel determining the normal load-receiving level of the arm, and means for vertically adjusting the axis of the wheel thereby to vary the normal load-receiving level of the arm, that portion of the length of the arm which is rearwardly of the supporting wheel being without support when the arm is in the normal load-receiving position.

2. A lift truck comprising a chassis, a motor housing, parallel links connecting the housing to the chassis whereby the housing may be raised and lowered relatively to the chassis, a motor device within the housing operative to raise and lower the housing, a lift arm rigidly iixed at its forward end to the housing, and movable up and down with the latter, a lever arm pivotally connected intermediate its ends to the forward end of the lift arm, a supporting wheel for the housing mounted at one end of the lever arm, said Wheel determining the normal load-receiving level of the lift arm, that portion of the length of the lift arm which is rearwardly of the supporting wheel being without support when the lift arm is in the normal load-receiving position, and means for vertically adjusting the opposite end of the lever arm thereby to vertically adjust the axis of the wheel to vary the normal load-receiving level of the lift arm.

3. A lift truck comprising a chassis, a motor housing, parallel links connecting the housing to the chassis whereby the housing may be raised and lowered relatively to the chassis, a motor device within the housing operative to raise and lower the housing, a lift arm rigidly fixed at its forward end to the housing, and movable up and down with the latter, a lever arm pivotally connected intermediate its ends to the forward end of the lift arm, a supporting wheel for the hous ing mounted at one end of the lever arm, said wheel determining the normal load-receiving level of the lift arm, that portion of the length of the lift arm which is rearwardly of the supporting wheel being without support when the lift arm is in the normal load-receiving position, a rod pivotally connected at one end to the opposite end of the lever arm and extending upwardly and projecting through the top of the housing and having a collar below the top of the housing, a helical spring havmg opposite ends engaging the collar and top of the housing respectively and normally urging the rod downwardly, the projecting end of the rod having screw threads, and a hand wheel threadedly mounted on said projecting end accessible from the top of the truck and operative, on rotation, to vertically adjust the rod, thereby to vertically adjust the axis of the wheel to vary the normal load-receiving level of the lift arm.

NATHAN'IEL WARSHAW.

REFERENCES Q'ITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 2,415,090 Framhein Feb. 4, 1947 2,417,394 Framhein Mar, 11, 1947 2,417,395 Framhein Mar. 11, 1947

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