US 2804218 A
Description (OCR text may contain errors)
Aug. 27, 1957 R. L SYLVESTER ETAL LOAD TRANSFER MEANS FOR LIFT TRUCKS Filed Dec. 31, 1955 2 Sheets-.Sheet l 6 .5N/v /V @0MM/f IN VEN T ORS BM/W Aug 27, 1957 R. sYLvEs'n-:R ETAL 2,804,218
LOAD TRANSFER MEANS FOR LIFT TRUCKS Filed Deo. 3l, 1955 2 Sheets-Sheet 2 FTE.E
a z5 F155 ZZ INVENTORS.
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LOAD TRANSFER MEANS FR LIFT TRUCKS Rowland L. Sylvester, Mishawaka, Ind., and Glenn N. Romina, Watervliet Township, Berrien County, Mich.
Application December 31, 1953, Serial No. 401,478
3 Claims. (Cl. 214-16.4)
This invention relates to load transfer means for lift trucks, and more particularly to a device for mounting a load upon a lift truck and for discharging the load from the lift truck in an economical manner.
The storage of goods in factories and warehouses in a manner to be readily accessible is important in many business operations. Many devices have been developed to speed the handling of materials and to render it economical. Two of the most important material-handling items 'presently used by business and industry are the fork lift truck and platform type of work carriers, such as pallets, skids and boxes which rare supported in elevated position relative to a supporting surface by means Aof uprights or legs carried thereby, which enable the forks of a fork lift truck to engage thereunder.
The use of fork lift trucks and elevated work carriers engageable by the truck forks is economical of Lman power but requires large storage spaces in Warehouses. In particular, space must be provided within which fork lift trucks can be maneuvered and turned. Thisnecessitatcs the provision of wide aisles so .that a truck may travel through the aisle to a point at which .the desired work carrier is located and kthen may turn to head .toward a selected work carrier in order that its forwardly projecting fork arms may pass under the work carrier between the upright supports thereof to position it to lift the work carrier. The truck requires space lto permit it to back up with its load until the load is clear of adjacent stored items, and then must have additional freedom to turn lengthwise rof the aisle to move'tothe discharging station. lt will be evident that where a warehouse contains a large number ofvditferent items, all of which must be accessible for selection at will, `preferably without requiring'shifting of other items in order to reach the desired item, a very large proportion of the .floor space of such a warehouse must begiven over to aisles and passageways so as to make possible themaneuvering of the fork lift truck which has been described above.
It is the primary object of this invention `toprovide a novel load transfer means for lift trucks which will reduce the space required in a warehouse .to maneuver lift trucks and which will increase substantially vthe percentage of floor space of a warehouse which may be devoted to material storing purposes.
A further object is to provide a device loffthis characier which will permit loading and unloadingofa .lift
truck from the side thereof by power actuated means.
A further object is to provide a load transfer-means for lift truckshaving means for shifting Jaload laterally relative to a lift truck and for raising and lowering the load when in a laterally offset position relative to the lift truck.
A further object is to provide a self-powered truck having a substantially horizontal vertically lshiftable projecting load carrier, which is characterized by alaterally extensible and retractable part and selectively operable means for actuating the same, and also by a vertically nite States Patent adjustable Work-engaging and supporting part upon the extensible part and provided with selectively operable power means for actuating the same.
Other objects will be apparent from the following specication.
In the drawings:
Fig. 1 is a side view of substantially schematic nature illustrating a fork lift truck having our improved load transfer means mounted thereon;
Fig. 2 is a fragmentary front View of our improved load transfer means mounted 'upon a vfork lift truck in load-transferring position or relation to a work storage rack;
Fig. 3 is a top plan view -of our improved load transfer device positioned in loading and unloading relation to a work support;
Fig. 4 is a vertical section view taken on line 4-4 of Fig. 3;
Fig. 5 is a `vertical sectional view taken on line 5-*5 `of Fig. 3;
Fig. 6 is a fragmentary side elevation of a portion of the work carrier in elevated position; and
Fig. 7 is a detail axial view of one of the power members employed in the device.
Referring to -the drawings which illustrate the prelferred Yembodiment of the invention, the numeral -10 designates a'self-propelled vehicle of the type commonly 'known as a fork lift truck, vwhich is mounted upon wheels 1.2 and is provided `with -controls V(not shown) by which its movement Vand operation may be effected by an operator. In the .usual form such trucks include a part upon -whichthe operator rides. The truck .mounts upright .members 14`adapted to be traversed by substan- .tially horizontal fork lift .arms 16.which are .controlled by positioning means (not shown) .of .power operated character and capable of supporting, elevating .and lowering a 'load mounted upon the .fork arms. .The fork arms will preferably `project lengthwise o'f lthe truck .10 and 4preferably forwardly thereof. The fork lift trucks which are now available on 'the market vary :as .to in- --dividual construction thereof, but we contemplate that this .invention may be practiced `with any such truck .regardless of its source ,of manufacture or individual deslvgn.
`Our improved load transfer `means isdesignatedgen- -erally by thefnumeral 20 and is supported upon the fork arms .or horizontal supports 16 of the fork lift truckin any manner found suitable. Thus it may beapplied or mounted as `a fixed and permanent lpart ofthe yforklift truck in the manner illustrated in Fig. 41, vor it mayrbe mounted .upon elongated at tubes .or `sleeves or ,guides 22 Whichiit snugly but detachably upon the arm 16, as
illustrated in Fig. 4 or -5.' The lateralprojection `of the parts will not tbe-great and preferably 'will l`not be substantially/greater Vthan .the overall widthxoffthe fork lift truck 10.
A wheeled extensibleand retractible unit is .supported by and traverses the 'horizontal guides ,26. As here shown, the extensible .unit'includesa frame member '28 having rigid downwardly, projectingside rails '30 .anda rigid downwardly'projecting end -wall "32. Each -of 'the kfork arms 16 will be small.
longitudinal rails 30 mounts a plurality of closed spaced pins or axle members 34. Each axle member' or stud mounts a roller or wheel 35 of a diameter which is :comparatively small. The axle studs 34 are so located that the rollers 36 will project below the bottom edge of the longitudinal rail 30 so that `they may bear upon and traverse the guide members 26 while the bottom edges of the rails 30 are held slightly above said guide surfaces. Each roller will have a slight clearance with the frame 28 in the preferred construction, but the arrangement preferably will be such that the vertical dimension of the extensible unit and the spacing of the frame 2S from the will preferably be of substantially theV same length as the guide members 26. The wheels or rollers 36 will be close spaced so that a substantial number 'thereof are provided, as shown in Fig. 5, and theV axle members 34 will pref The extensible member 28 erably be studs of short length, each mounting or journ naling only one roller positioned adjacent to the rail 30 which carries the stud or axle. The axes of rotation of the rollers 36 will be parallel to each other and substantially parallel to the fork arms 1,6 so that the extensible member may travel in a straight path lengthwise of the guide members 24. Upright flanges 38 on the guide memhers 24 will restrain the extensible member from travel in a path angularly displaced from the lengthwise direction of said guide members.
The laterally extensible unit includes a rigid loadengaging member 40 having downwardly extending rigid members 42 at opposite sides thereof. Thus the parts 40, 42 may be of substantially inverted .lJ-shape in cross-scetion, as best seen in Fig. l, of a width substantiallyV equal to the width of the extensible frame member 28 so that the downwardly projecting parts 42 may bear upon the opposite sides of the member 28 and be substantially vertically aligned with the vertical parts 30 of the member 28 in their normal relation or position. The members 30 and 42 at each side of the structure may be connected by a plurality of similar links 44, each pivoted at one end at 46 to the rail 42 and pivoted at its opposite end 48 to the rail 30. The links 44 are rigid, are parallel to each other, and extend at an angle to the vertical in the normal relation of the parts when the bottom edges of the rails 42 bear upon the top of the member 28. This construction permits relative longitudinal movement of the parts 40 and 28 to a position as illustrated in Fig. 6 in which the depending rails 42 are clear of the member 28 and the top surface of the part 40 is elevated relative to the position illustrated in Fig. 2. Alternatively, other means may be provided to guide raising and lowering of the member 40.
The device is equipped with power actuated means for extending it laterally relative to the fork arms or support 16. Such means may be constructed to operate by any selected type of motive power, such as hydraulic, electri-V cal or pneumatic. We prefer to have hydraulic means as here illustrated. This mechanism is best illustrated in Fig. 4 and comprises a cylinder 50 having a piston (not shown). The cylinder piston unit is of the double acting type having ports 52 with which lines connected to a pump and reservoir (not shown) are connected. The system will be of the usual type having a control valve (not shown) which will permit the supply of liquid under pressure to a selected one of the two end ports 52 and which will connect the opposite end port with the intake of the pump so as to cause travel of the piston in desired direction and in a desired stroke in that direction. The power unit has aconnector 54 projecting from one end thereof, and a connector 56 projecting from its opposite end. One of the connectors 54, 56 will constitute a stem mounted on a piston and shiftable relative to the cylinder 50. The
at the opposite ends of the cylinder,
Y extensible member 28.
other connector will be carried by and `project longitut pressure.
4, nection at 5S with earsy or other rigid projecting members 60 carried by the base of the device. Thus the members 6!) project upwardly into the member 28, 30 preferably at the center thereof, as seen in Fig. 3, and may be connected xedly to fork arms 16 or to a base separate from those fork arm and associated with the sleeves 22. The projection 56 at the opposite end of the power member passes through an aperture in the downturned wall 32 of the extensible unit and is tixedly anchored thereto by nuts 62 or other fasteningmeans mounted upon the part `The power unit Sti will preferably be of a length so that only one, or at most a few, of the rollers 36 will remain in engagement with the track 25 when the unit is extended at its maximum projection. It is important that at least one roller 36 remain in contact with the guide members 26 so that retraction of the device may proceed without difficulty or interference.
The device is also provided with power operated means for elevating and lowering the platform 4t] relative to the retractible frame 23 between the lowered position shown in Figs. l and 2 and the elevated position shown in Fig. 6. `Any source of power may be employed for this purpose, but we have yelected to illustrate the same as an hydraulic power member `in Fig, 5. The hydraulic power member comprises a cylinder 70 `having a double acting piston 72, said cylinder having ports 74 at its opposite ends for the admissionand discharge of liquid under The ports 74 will be connected by fluid lines (not shown) with the hydraulic pressure system which may include a pump, a reservoir, and control valves, in the manner well understood in the art and so arranged that control of the valves will make possible the movement of the piston 72 in a selectedy direction within the cylinder 70. Since the elevation of the platform member f 42 to its maximum height occurs when the links 44 are at vertical position as illustrated in Fig. 6, it is necessary that the stroke of the piston within the cylinder shall be limited in at least one direction so that the movement of the unit cannot proceed beyond the position of maximum elevation. Any suitable means may be provided for limiting the stroke of the piston and, as illustrated in Fig. 7, we have shown stop members 76 in the nature of rings seated in grooves in the interior of the cylinder '70 and projecting into the path of the piston 72 as means for limiting the stroke of the piston. A connector 7S extends from the cylinder 70 at one end thereof and has pivotal connection at 80 with a bracket 82 which is fixed to the The piston has connection through a stem 84 with a bracket 86 carried by the platform member 40. The connection of the parts is such that the cylinder will preferably be inclined, as best seen in Fig. 5, and in cases where the platform supporting cxtensible member 28 is of solid plate construction, an aperture 88 is formed therein to accommodate extension therethrough of a part of the cylinder and of the stem 84.
Where hydraulic controls are employed, it will be understood that the reservoir and the pump and control valves will be mounted uponV the lift truck 10 with the 'pump (not shown) having a driving connection with the power units 70 are illustrated located on opposite sides` of the power unit 50. t
The goods or material to be handled and maneuvered Aby the device will be supported in racks in a warehouse "andpreferably will be supported on tables or supports adjacent to or alongside machines in a factory, so that each item will be elevated above Ythe licor level upon which the tractor runs. For this purpose the goods, as illustrated schematically at '90 in Fig. 2, are mounted upon pallets vor skids providing a horizontal supporting member'92 elevated relative to a supporting surface by downwardly extending supports, such as flanges, legs or the like, as illustrated by the numeral 94. The spacing of the supports 94 will be greater than the total overall width of this device, as best illustrated in Fig. 1. Likewise, as best illustrated in Fig. 2, the height of the support 94 and of the bottom surface of the platform member 92 of the pallet or the like -member will be greater than the collapsed elevation of the vertically shiftable pallet engaging platform 40 of this device. l
A rack is illustrated in Figs. 2 and 3 for supporting the pallets at sucient elevation so that this device may engage under the pallets. The rack as here illustrated will include uprights 96 interconnected by longitudinal horizontal members 98. The parts 96 and 98 will preferably be standard structural steel shapes, the uprights 96 being `shown in Fig. 3 ras being channel members, and the horizontal members 98 being shown in Fig. 2 as being angleirons. Fore and aft sets of structural members V96, 98 are interconnected by transverse horizontal structural members 100,`such as angleirons, which are bolted, welded t or otherwise secured to the structural members 96 or 93 vto serve to form a rack structure. The structural members r100 will preferably include horizontal plate portions adapted to support the upright portions 94 of the pallets. The 'spacingb'etween adjacent uprights 96 will be greater than the width of the pallet. Track means are also provided `on the rack Vat each pallet-receiving portion thereof and extending fore and aft horizontally thereon to be traversed by the rollers 36. As illustrated in Fig. 3, such track members '102 may be formed of angleirons. Alternatively, of course, the structural members 100 may have widened horizontal flanges of a width suicient to support 'the pallet edge and also to permit the rollers to 'run thereover. As best seen in Fig. 2, the front ends of the members 102 will preferably be downwardly curved at 104 projecting outwardly from the rack, for purposes 'tobe mentioned.
v In the use of the device, assuming that Ythe operator of 'a fork lift truck desires to removea pallet loaded with work pieces from a rack, he drives the fork truck in a path parallel and close to the front of Vthe rack until the fork 'arms are positioned opposite the compartment or location on the rack atwhich 'the desired work loaded pallet is located. He next operates the lift arms 16 carrying the new device to such an elevation that the track members 24 ofthe device are substantially at the sameflevel as the track members 102 on the rack. Thereupon the power operated extension member 50 is actuated bythe operator to shift the extensible member 28 laterally. The member 28 travels on its rollers 36 which successively leave'engagement with the horizontal portion 26 of the track members 24'of the device and move it to vengagement with the track members 102 of the rack. In the event the Ylevel of thetrack members 24 is slightly lower than the levelrof the member 102, the rollers will engage the cam surface 104 as they leave the track 26 and will then be guided onto the track portion 102. At this time the vertically adjustable member 40 will be retracted in the Fig. 2 position and the laterally extensible unit will be compact vertically so that Ait will be free to travel under the platform 92 of the pallet to assume a position substantially in register `therewith and therebelow.V When this position is reached operation of the extension member `50 vis stopped.
VPower member 70 is then yoperated from the position Villustrated'in Fig. V5 in a `direction toward the right as viewed in Fig. v5, thus laterally shifting the platform member,401relativeto the laterally extensible member 28.
Y as determined from This movement is guided by the pivoted links 44 which swing in -an arc to the .position Aillustrated in Fig. 6, and in so doing raise the 'level of the member '40 and bring it into engagement with the bottom of the platform 92 lof the pallet and subsequently lift that pallet and its contents out of engagement with the part of the rack, such as `the Vmembers 100, upon which the pallet has previously rested. Thereupon, operation of the power member 70 is stopped, andthe power member 50 is then again actuated but this time -in a retracting position to return the parts to Athe position illustrated in Fig. 4.
The forklift truck is then moved to the desired delivery position or station alongside of a platform or table, and, after having been properly spotted or located, it is stopped and the power member 50 is again operated to laterally extend the member 28 and its associated parts, including the load, after the fork arms have been located at a position or elevation which will insure that the Vrollers 36 of vthe, work carrier will engage the table top when the extension member 50 is operated. During the time that the fork lift truck is moved from one location to another, the power operated positioning member 70 may be extended to hold the pallet clear of the fork lift arms, or, alternatively, it may have been moved to the Fig. 5 position to permit the bottom edges of the support 94 of the pallet to rest upon the fork arms. In any event, when discharge of the load is to occur, the operator makes sure that the power member '70 has been operated to elevate the pallet platform 40 so that the pallet support 94 is clear of the fork lift arms 16. The lateral discharg ing movement of the extensible member 28 proceeds to such an extent as to deliver the work above the table, whereupon the power member 50 is deenergized to stop the lateral extending movement of the part 28. Thereupon the power member 70 is operated to move the platform 40 in a lowering direction, thus permittting the pallet supports 94 to engage the table or delivery point and to effect disengagement of the new device with the pallet. When the laterally extensible device has been lcontracted vertically to a position clear of the work, the
power member '70 may be deenergized, and the power member S0 maybe energized to return the work carrier to a centered relation 'to the fork lift arms'l and to thereupon permit movement of the fork truck to the location of its next assigned load.
It will be evident from the foregoing description of the operation ot' this device that the aisles between racks in a warehouse need only be wide enough to `permit a truck to travel therealong with reasonable clearance while carrying a loaded pallet. Thus the spacing between adjacent racks may be substantially less than a dimension represented by the overall length of the fork lift truck its rearmost position to the tip of its fork lift arms. Such spacing is to be compared to a required spacing at present which is greater than the overall length of a truck in order to permit a fork lift truck to head into the rack in order to take on a load. Maneuvering of the truck is also greatly reduced since it is not necessary that any turn shall be made within an aisle and, instead, the operator of the truck may merely head his truck into the aisle, take on the load, and then back up in the aisle until he reaches a passageway wide enough to permit further maneuvering. This permits an arrangement of a warehouse having one wide aisle or passageway sufficient to .permit turns into perpendicular extending parallel aisles which are of comparatively narrow width. Consequently, a much higher proportion of the floor space of a warehouse may be used for the storage of goods than is possible under present conditions using conventional fork lift trucks which must head into the racks in order to pick up a load.
One interesting and important consideration of this invention is the use of a large number of close spaced rollers 36 extending substantially full length of the member l2S `and providing a plurality of points of support for the member 28 and the parts carried thereby. "This arrangement is important because it limits to ,a substantial extent the occurrence .of unbalance laterally `of the truck incident to the loading'and unloading operation. Viewing Fig.` 2 it will be apparent that only a slight amount of lateral movement of the load-carrying unit can occur with relation to the uprights 14 of the fork lift truck before the leading rollers 36 engage the guide member 102 of the rack. Consequently, no danger exists of overbalancing the truck laterally, and the weight of the load is progressively taken by the rack or the work support after the iirst roller engages that work support. Furthermore, the amount of lateral unbalance which can occur before the first roller engages the rack is limited. By reason of this situation, the factor of safety of this device is high and danger of unbalance is negligible The most successful and efficient operation of the debeen illustrated and described, it will be understood that vice requires accuracy of positioning of the truck, the
extensible unit and the truck lift arms relative to the rack. and to the storage space of the skid or other work Carrier to be removed from the rack or delivered thereto. r[he first requirement of accuracy as to position relates to the position of the truck so that it is substantiallyr parallel to the rack and spaced a predetermined distance therefrom. Various means may be provided to insure such a position. One such means is to provide a painted guide stripe upon the floor which may be observed by the truck operator as he approaches the selected space in the rack and which he may follow to insure parallelism of the truck to the front of the rack and to insure accurate spacing of the truck from the rack.
The next requirement of accuracy of position is that the truck be so positioned that the extensible device is free to move'properly into the rack to engage a work skid therein or to deliver a work skid thereto. This resolves itself into several factors, one of which is the position of the truck relative to the rack upon the door, and another is a control of the elevation of the lift forks upon the mast 14. Still another control position may be assurance that theextensible unit is horizontal, in other words that the forks do not dip out of horizontal posilion under load. A simple means for insuring such positioning is illustrated in Figs, l and 3 and constitutes the mounting upon the device of a source of `light 110 for yprojecting a beam of light 112 toward the rack.l As
shown, the means 316 is mounted upon one of the sleeves 22 which maintains a tixed orientation relative to the guides 24 and to the elevation of the fork arms 16 of the truck. The rack and preferably the uprights 96 thereof will have juxtaposed to each storage space `or compartment therein a mark (not shown) which will be` so related to that storage space that when the operator observes that the beam of light is centered on that mark,
which may be a cross to enable to operator to observe both vertical and horizontal deviation from true register, the worker can be assured that his device is positioned properly with respect both to alignment of the device with the storage space vertically and alignment thereof with the storage space horizontally or lengthwise of the rack. in the event it is desired to provide means to insure the worltcr that the horizontal position of the device is accurate, two such lights may be provided at vertically spaced points adapted to shine upon similar marks upon the rack. If the light beam strikes both of these marks upon the rack simultaneously, the operator is insured of registry on the vertical and horizontal, and also is insured of a true horizontal position of the platform member 40. Any tilting observed by they device will require tilting of the mast, as is commonly possible through controls provided upon the lift truck.
changes in construction may be made within the scope of the appended claims without departing from the spiritof the invention. A
l. Load transfer means for shifting a load mounted on a carrier having spaced substantially upright supports, comprising a self-propelled dirigible wheeled vehicle, cantilevered fork arms carried by and projecting forwardly beyond the front wheels of the vehicle, means for raising and lowering said fork arms on said vehicle relative to a low level position adjacent the surface on which the vehicle travels, a power unit on said vehicle, a base detachinto the rack, a stop (not shown) may be provided in the ably carried by said fork arms `and having a guide extending transversely of said fork arms, an extensible unit traversing said guide and including anti-friction supporting means, selectively operable means on said base actuated by said power unit for shifting said extensible unit along said guide, a rigid load-carrier-engaging member narrower than the spacing of the carrier supports carried by said extensible unit, and selectively operable means actuated by said power unitin all operative positions of said extensible unit for raising and lowering said last named member relative to said extensible unit between low level and high level positions, said last named member elevating said carrier clear of said base in high level position and being shiftable freely under said carrier and between the supports thereof in low level position.
2. Loall transfer means for shifting a load mounted on an elevated work carrier having a horizontal part and spaced downwardly projecting supports to and from a rack having a plurality of storage compartments each including track means and load supporting means, comprising a selfpropelled dirigible wheeled vehicle, a power unit on said vehicle, verticallyrshftable cantilevered load-supporting means carried by and projecting forwardly beyond the wheels of the vehicle and substantially horizontally from said vehicle, positioning means for raising and lowering said load-supporting means relative to a low level position adjacent the surface on which the vehicle travels, a base detachably carried by said supporting means and having a guide, an extensible unit having a plurality of spaced anti-friction supporting means and shiftable in a predetermined path on said base laterally of said vehicle to and from the track means of said rack, selectively operable means `on, said base actuated by said power unit for shifting said extensible yunit in said path on said base into and from a selected compartment of said rack, arigid load-engaging member carried by said extensible unit, and selectively operableV means on said extensible .unit and actuated by said power unit for shifting said load-engaging member between elevated and lowered positions on said extensible unit in all operating positions of the, latter, said load-engaging member being narrower than thetspacing between the supports of saidelevated work carrier, said load-engaging member in its ,lowered position being shiftable freely below the horizontal part of said work carrier and in its elevated position liftingthe carrier to a position with its downwardly projecting supports clear `of the surface traversed by said wheeled extensible unit. p 3. Load transfer means for shifting a load mounted on a work carrier having a horizontal part and spaced downwardly projecting supports, comprising a dirigible selfpropelled wheeled vehicle, vertically adjustable cantileveredforwardly projecting load supports on said vehicle extending beyond the front wheels thereof, positioning means for elevating and lowering said load supports rela tive to a low level position adjacent the surface on which the vehicle travels, a base adapted to be carried detachably by the said load supports of said vehicle, horizontal guide means on said base adapted to extend laterally relative to said vehicle, an extensible unit having anti-friction supporting means shiftable on said guide, a vertically adjustable load-engaging member carried by said extensible unit, said load-engaging member having a lowered position fitting with clearance between the supports and below the platform of a work carrier supported on the base and having an elevated position for supporting a work carrier spaced above the said load supports of said vehicle a hydraulic power unit carried by said vehicle, hydraulic means carried by said base for shifting said extensible unit along said guide, hydraulic means on said extensible unit References Cited in the tile of this patent UNITED STATES PATENTS 1,824,201 Eisenberg Sept. 22, 1931 1,879,713 Scott Sept. 27, 1932 2,299,150 Kennedy Oct. 20, 1942 2,416,071 Shonnardl Feb. 18, 1947 2,584,240 Stewart Feb. 5, 1952 2,626,065 Sanders et al. Jan. 20, 1953 2,633,809 Robinson et al Apr. 7, 1953 2,663,434 Pierce Dec. 22, 1953