US 3659733 A
An attachment for conventional industrial lift trucks to enable the truck to work in narrow aisles and manipulate pallets in front of and to both sides of the truck, utilizing a crossed six-bar linkage and side shifter mechanism.
Claims available in
Description (OCR text may contain errors)
Unite States Sinclair et a1.
EQHHE [451 May2,1972
 NARROW AISLE ATTACHMENT  lnventors: Stuart W. Sinclair; Monroe .1. Dennis, both of Houston, Tex.
 Assignee: Anderson Clayton & (30., Houston, Tex.
 Filed: Dec. 11, 1970  Appl. No.: 97,225
 US. Cl ..214/730 [51 Int. Cl.  Field of Search ..214/730, 731, 670, 671
 References Cited UNITED STATES PATENTS 2,851,182 9/1958 Gehring ..214/730 Wendt ..214/73O Ulinski ..214/730 Primary Examiner-Gerald M. Forlenza Assistant Examiner-Lawrence J. Oresky Attorney.lames F. Weiler, Jefferson D. Giller, William A. Stout, Paul L. De Verter, ll, Duddley R. Dobie, Jr. and Henry W. Hope  ABSTRACT An attachment for conventional industrial lift trucks to enable the truck to work in narrow aisles and manipulate pallets in front of and to both sides of the truck, utilizing a crossed sixbar linkage and side shifter mechanism.
7 Claims, 14 Drawing Figures Patented May 2, 1972 4 Sheets-Sheet l 7,04; was
Patented May 2, 1972 4 SheetsSheet U 70 INVIiN'fURJ Patented May 2, 1972 4 Sheets-Sheet 4 BACKGROUND OF THE INVENTION This invention relates to an attachment for industrial lift trucks, and more particularly a narrow-aisle attachment and method which enables the truck to manipulate loads or pallets in front of and at both sides of the truck without requiring the truck to turn in the aisle.
Pertinent prior mechanisms to provide side-loading abilities for lift trucks are illustrated in the patents to Gehring, US. Pat. No. 2,851,182, Ulinski, US. Pat. No. 2,975,923 and Haddock, US. Pat. No. 3,166,209. The levers and pivoting mechanisms of the foregoing, and other similar prior art devices, generally extend forwardly from the fork carriage to such an extent that the load-carrying capacity of the truck is reduced. Most of the prior devices require linkages and guide mechanisms which are wider than the standard front carriage plate of the truck, which results in the attachment taking more width than is desirable.
SUMMARY The narrow-aisle attachment of the present invention generally includes a crossed arm six-bar linkage rotatably mounted on a load-support tree which is attached to a telescoping side shifter mechanism. The use of the crossed arm six-bar linkage, as hereinafter described, allows the front plate, to which forks or grippers or other load manipulating devices are attached, to be rotated a full 90 to either side of the truck, as well as allowing the front plate to be folded into a normal lift truck configuration. The crossed arm six-bar linkage further enables the entire rotating mechanism to be contained in less width than the standard lift truck front plate and allows the pivot points to remain within the standard lift truck front plate width. The load-support tree includes an equalizer to prevent twisting of the front plate and linkage when a load is engaged from the front, or either side. The telescoping side shifter mechanism allows the load handling devices mounted on the front plate to be manipulated transversely of the truck when the front plate is in its normal position, and allows the front plate to extend beyond either side of the truck when it is rotated 90 from the truck axis.
The narrow-aisle attachment of the present invention is designed to be utilized with a standard lift truck by attachment to the standard truck carriage plate. Maximum utility of the present invention is attained when the lift truck includes an elevator mechanism, but additional side shifter mechanisms on the truck are unnecessary. The thin profile of the attachment when facing forwardly prevents an excessive loss in load-carrying capacity.
Thus, it is the general object of the present invention to provide a narrow-aisle attachment which will enable a standard lift truck to manipulate loads in front of, as well as at both sides of the truck.
A further object of the present invention is to provide an improved method for structuring and manipulating a six-bar linkage lift truck attachment. Other and further objects, features and advantages will be apparent from an examination of the following description of the presently preferred embodiment of the invention, given for the purpose of disclosure, when taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS Like character references designate like parts throughout the several views of the drawings;
FIGS. 1 through 7 present a diagramatic top view of the invention being manipulated to withdraw a pallet from the aisle adjacent to a lift truck,
FIG. 8 is a perspective view of the present invention illustrating the manipulation of a loaded pallet from the aisle, similar to FIG. 4,
FIG. 9 is a perspective view generally illustrating the overall configuration of the present invention,
FIG. 10 is a partial sectional front view of the present inventron,
FIG. 11 is a partial sectional top view taken along line 11- ll of FIG. 10,
FIG. 12 is a side view, taken along line 12-12 of FIG. 10,
FIG. 13 is a partial top view taken along line 13- 13 of FIG. 12, and
FIG. 14 is a partial sectional top view taken along line 14- 14 of FIG. 12.
DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings, and particularly FIGS. 1 through 7, the reference numeral 10 generally refers to the narrow-aisle attachment of the present invention which is mounted on a conventional industrial lift truck 12. The attachment I0 includes a front plate 14, here shown as a standard industrial lift truck tool-holding accessory carriage plate on which are hung conventional forks 16. Other load-gripping and manipulating devices may be hung from the tool-holding front plate 14 in a conventional manner, or the front plate may be altered for special purposes as shown in the prior art.
Adjacent the front, and to the left of truck 12 is a standard pallet 18, on which various loads may be placed, in a conventional manner. Notice particularly in FIG. 1 that the axis of the attachment 10, center line of the forks l6 and truck 12 are lined up. The pallet 18 may be sitting on the floor, or raised from the floor on a pallet rack or on top of another load, or the like. Obviously, the attachment 10 must be raised by the lift truck mast so that the fork 16 will fit within the fork-engaging spaces of the pallet 18.
Referring now to FIG. 2, the attachment 10 and the fork 16 have been shifted to the right, so that the center lines do not correspond with that of the truck 12. As will be explained hereinafter, shifting to the extreme side releases the latch which holds the plate 14 against the attachment 10 at that side, thereby allowing the attachment to rotate the plate 14 in the opposite direction. Thus, in FIG. 2, shifting the plate 14 and the attachment 10 to the extreme right unlocks the latch on the right side, allowing the attachment 10 to rotate the plate 14 to the left, as is illustrated in the successive dotted, dashed and full lines of FIG. 3. The steps for rotating the plate and forks in the opposite direction are just the reverse of those indicated above.
The plate 14 and forks 16 shown in full lines in FIG. 3, are not aligned with the pallet 18. To remedy this, the operator of truck 12 moves the truck forward and/or backward (as the case may be) to align the forks 16 so that they will fit within the fork space of pallet 18, as seen in FIG. 4. Thereupon, the rotated front plate is shifted to the left so that the forks slide within the fork space of the pallet 18, in a conventional manner. Notice that the forks 16 are not centered in the pallet because the near edge of the pallet must clear the attachment frame when the pallet is engaged by the truck 12 and removed from the storage point, as shown in FIG. 5.
As seen in FIG. 6, the plate 14 is shifted to the extreme right and then the carriage is rotated as shown by the solid, dashed and dotted lines of FIG. 6, until the plate 14 faces to the front. If the pallet is overly deep, it may be necessary for the operator of the truck to back the truck so that the edge of the pallet clears the far corner of the storage space, when performing the operation shown in FIG. 6.
Thereafter, the plate 14 is side-shifted to the center to line up the various center lines, if desired, as previously shown in FIG. 1. If it is also necessary that the pallet be exactly centered, then the truck may be moved away from the edge of the storage area on the left, and then the pallet may be shifted with the side-shifter mechanism in a conventional manner. Of course, if desired, the pallet may be carried by the truck with the plate at to the direction of truck travel, similar to that shown in FIG. 5. Obviously, loads longer than the width of doorways may be carried parallel to the direction of the motion of the truck, in a manner similar to that shown in FIG. 4.
Turning now to FIG. 8, the narrow-aisle attachment is shown in a position comparable to FIG. 4. In this instance, the plate 14 includes not only the forks 16, but also a carton hood attached to the plate 14. FIG. 8 also illustrates the use of the narrowhaisle attachment 10 on a truck 12 to manipulate a pallet 18 located above ground level. The attachment 10 is shown attached to the standard two-piece attachment and tool-holding plate 22 of the truck. This plate is, in a conventional manner, moved vertically by the elevator 24.
Referring now to FIGS. 10, 11 and 12, a detailed description of the narrow-aisle attachment 10 is given. The narrowaisle attachment 10 generally includes the six-bar linkage 26, the side-shifter mechanism 28, the load-support tree 30, and the latches 32. Generally, the six-bar linkage supports and pivots the plate 14, to which are attached the load-engaging devices, such as the forks 16. In turn, the load-support tree 30 supports the linkage 26, and through an equalizer arrangement, prevents twisting thereof. The side-shifter mechanism 28 in turn supports the load-support tree and operates in conjunction with the latches 32 to allow pivoting of the six-bar linkage 26. The base of the side-shifter mechanism in turn mounts on the standard attachment and tool-holding plate 22 of the lift truck 12.
The six-bar linkage includes the load-support tree 30, the plate 14, and two pair of generally s qnmetrical arms 34, 36 and 38, 40. The tree 30 generally includes brackets 42 and M,
which are symmetrically arranged with pivot pins 46 pivotally supporting inner arm 34 and pivot pins 48 pivotally supporting inner arm 36 at both the top and bottom. lnterconnecting and allowing pivotal movement between arms 34 and 38 are pivot pins 50, while similarly interconnecting arms 36 and 40 are pivot pins 52 at both the top and bottom. interconnecting and allowing pivotal movement of the front plate 14 and outer arm 38 are pins 54, while similarly interconnecting the plate 14 and outer arm 40 are pins 56. Note, as best seen in FIGS. 11 and 12 that pins 54 and 56 are not coaxial, but are offset, so that when the plate 14 is parallel to the lift truck plate 22, the arms 38 and 40 cross. Plate 14 therefore forms a link in the six-bar linkage.
Thus it is seen that the six-bar linkage includes six distinct bars, with the ends of each element pivotally pinned to the end of the next element. However, as opposed to conventional linkages, two of the bars overlap, or cross each other, which results, at least in part, in the unique action of the present in vention.
To manipulate and control the pivoting of the arms, motor means are connected between the load-support tree 30 and inner arms 34 and 36. These motor means include hydraulic rams 58 and 60. As seen in FIG. 9, ram 58 is pivotally connected to the tree 30 by pin 62 and to arm 34 by the pin 64. Similarly, ram 60 is pivotally connected to the tree by pin 66 and to arm 36 by the pin 68. The rams 58 and 60 are doubleacting and arranged for suitable conventional hydraulic actuation.
Extension of ram 58 causes arm 34 to pivot outwardly from a position adjacent the frame 70 of the attachment 10 to a position somewhat past perpendicular to the frame, as seen in FIG. 11. By the same token, extension of the ram 60 causes the arm 36 to move from a position adjacent the frame 70 to a position somewhat past perpendicular thereto, as seen in FIG. 11. The rams are extended at the same time so that the arms butt together as shown in FIG. 11. Retraction of the two rams causes the arm 34 and 36 to rotate about the pivots 46 and 48 until the pivots 50 and 52 are adjacent the frame 70. As will be noted hereinafter, when the plate 14 is adjacent the frame 70 and the latches 32 are engaged, the rams 58 and 60 may not be extended.
Plate 14 includes a latch assembly 32 at either end thereof. The latches are designed to engage with roller catches 72 and 74. Roller catch 72 is mounted on outer arm 38 adjacent the pivot pin 50, while roller catch 74 is mounted an outer arm 38 adjacent pivot pin 52. When the front plate 14 is parallel with the frame 70 (i.e., adjacent the attachment 10 as seen in FIG. 1) the latches 32 on both sides of plate 14 are engaged with their respective roller catches 72 and 74. However, when the front plate 14 is to be rotated to the left, as in FIG. 11, then roller catch 74 is disengaged, in a manner to be hereinafter described, and the front plate remains latched only to roller catch 72. This retains plate 14 adjacent arm 38.
Referring now to FIG. 13, it is seen that roller catch 72 is attached to arm 38. Extending backwardly from plate 14 is the bracket 75 to which is pivotally attached a cam 76. The cam 76 prevents movement of roller catch 72, and consequently holds plate 14 adjacent arm 38. Attached to the cam 76 is a suitable operating lever 78 which is manipulated to rotate cam 76 in the direction indicated by the arrow, to release catch 72. The cam 76 is suitably biased, as by a spring or rubber block, to ordinarily remain in the position shown in FIG. 13. The symmetrical latch on the opposite end of plate 14 is shown in FIG. 11 with the addition of prime marks to the various numerals.
Mounted on the face of the frame 70 are racks 80 at the top and 82 at the bottom. These racks are engaged by pinions 84 and 86 which are suitably attached to shaft 83, at opposite ends thereof. Shaft 88 is joumalled within tree 30. Mounted at the top of the tree 30 are appropriate rollers 90 which engage the track 92 at the top of the frame 70. Mounted at the bottom of the tree 30 are rollers 94 which engage a track 96 along the bottom of the frame 70. Attached vertically behind the tree 30 are rollers 98 (seen in dotted lines in FIG. 12) which ride upon track 100 of the frame 70. The rollers 98 vem'cally support the tree 30, while the rollers 90 and 94 retain the tree adjacent to the frame 70.
The racks 80 and 82, in combination with the pinions 84 and 86, operate as an equalizer to prevent twisting from the vertical of the tree 30 when loads are manipulated by appropriate tools attached to plate 14.
The side-shifter mechanism 28 is here shown to be telescoping so that it includes primary and secondary hydraulic rams to selectively position the tree 30 transversely across the front of the lift truck 12. The secondary rams are actuated in response to an increase in resistance to movement and constitute a refinement of the present invention, giving a somewhat broader range of operating area, and may be dispensed with if less maneuverability can be tolerated. Other devices may be utilized to provide equivalent movement.
Referring now to FIG. 10, the primary side-shifting mechanism includes a motor here shown as rams 102 and 104. Each of rams 102 and 104 are here shown as single-acting, with the cylinder ends being attached to the frame '70 oriented in opposite directions. Attached to the piston rod 106 of ram 102 is a sprocket 108, while attached to the piston rod 110 of ram 104 is a sprocket 112. Attached to opposite sides of the frame 70 adjacent rams 102 and 104 is a chain 1 14 which engages the sprockets 108 and 112. The chain 114 may have suitable adjustment means 116 at either or both ends attaching the chain to the frame 70. The center of the chain is attached to the load-support tree 30 by bracket 118. Suitable hydraulic connections are made in a conventional manner to the rams 102 and 104. Entry of hydraulic fluid into ram 102 causes the piston rod 106 to extend, rotating the chain 114 about the sprocket 108 in the direction of the arrow, causing bracket 118, and therefore tree 30 to move in the same direction as the piston rod extends, only twice as fast because of the mechanical advantage. Similar, but opposite movement results when ram 104 is energized. The tree, of course, moves across the face of the frame 70 and is supported by the various rollers 90, 94 and 98. This in turn causes the six-bar linkage 26 to similarly move transversely across the face of the frame 70. This movement is substantial only if the plate 14 is positioned perpendicular to the frame 70. With the foregoing described primary side-shifter mechanism, the plate 14 may be manipulated to the edge of the frame 70.
It is sometimes desirable that the frame 70 itself may be shiftable to make the present invention more maneuverable. This is accomplished by the secondary side-shifting mechanism. Interposed between the frame 70 and the lift truck carriage plate 22 is a sub'frarne 120, seen in FIG. 12. The sub-frame 120 includes an upper bracket 122 and a lower bracket 124 which are fixedly attached, in a conventional manner, to the front carriage plate 22. A Z-shaped bearing 126 is interposed between the upper bracket 122 and the frame 70 to support the frame so that it may slide on the upper bracket. A vertical bearing 128 serves a similar purpose between the frame 70 and the lower bracket 124. Extending upwardly from the upper bracket 122 of the sub-frame 120 is a lug 130, which protrudes through a slot 132 in the frame 70- This slot is best seen in FIG. 1 1.
Secondary motor means are interposed between the frame 70 and the lug 130, here shown as secondary rams 134 and 136. One end of each ram is attached to the frame 70, and the opposite operative end is connected to the lug 130. Actuation of ram 134, for example, results in sliding the frame 70 away from the lug 130, which is fixedly attached to the lift truck carriage plate 22 through the upper bracket 122. In this manner, the frame 70 may be maneuvered bodily over a portion of the face of the carriage plate 22, thus extending the side-shifter range of the present invention. The rams 134 and 136 are hydraulically actuated in a conventional manner.
As was previously mentioned, when the inner arms 34 and 36 are rotated adjacent to the frame 70, then the plate 14 is moved to a position parallel to the lift truck carriage plate 22. In this position, the latches 32 are locked to the respective roller catches 72 and 74 on outer arms 38 and 40. To unlock either of the latches 32, it is necessary to engage the lever 78 which retracts the cam 76, as previously described. Mounted on the frame 70 are roller fingers 140 and 142. When the latches 32, which are attached to both arms 38 and 40, are moved to either extreme edge of frame 70, then the lever 78 or 78 will engage the finger 140 or 142, which unlocks the latch which is so touched. Thereafter, upon actuation of the rams 58 and 60, the inner arms 34 and 36 are rotated, as are the arms 38 and 40, resulting in the plate 14 being brought perpendicular to the attachment 10. Mounted on either side of the frame 70 are centering springs 138 which engage the subframe 120. The purpose of these springs is to provide a specific resistance before unlatching occurs and to partially center the frame 70 with respect to the sub-frame 120 when it is not desired that the frame 70 remain at the extreme end of its travel with respect to the sub-frame.
Referring now to FIG. 11, notice that the provision of requiring arms 38 and 40 to cross, or overlap, results in the ability of plate 14 to assume a position perpendicular to the frame 70. lfthe pivot points 54 and 56 were coaxial, then plate 14 could only be parallel to arms 38 or 40, but neither of these arms would be perpendicular to the frame. By utilizing the crossed arms, no motor mechanism is needed to rotate the plate 14. Furthermore, when the arms 34 and 36 are rotated so that they are adjacent one another, and when the frame 14 is locked to either arm 38 or 40, then the resultant linkage between points 50, 52, 54 and S6 is not a freely-moveable four-bar linkage, but two overlapped three-bar linkages, which are rigid.
Notice that there is no physical interconnection between arms 34 and 36 or between arms 38 and 40 to insure symmetrical rotative movement and alignment, because the rotative movement is not symmetrical. Typically, a six-bar linkage is considered unpredictable, whereas a four-bar linkage is considered predictable. However, in the present invention, both the start and finish of the rotative or pivotal movements are controlled, hence the start and end positions are predictable, thus resulting in the present-described motions.
Thus, it is seen that the present invention has provided an attachment for lift trucks which is particularly useful in manipulating loads in front of and at both sides of a lift truck. The method of the present invention is felt to have been adequately described with reference to the structure and generally includes maintaining two links of a six-bar linkage overlapped with one interposed link therebetween, and selectively latching the interposed links to the overlapped arms.
The present invention, therefore, is well adapted to carry out the objects and attain the ends and advantages mentioned as well as others inherent therein. While a present-preferred embodiment of the invention has been given for the purpose of disclosure, numerous changes in the details of construction, and the combination, shape, size, uses and arrangement of parts and order of steps may be resorted to without departing from the spirit and scope of the invention as hereinafter claimed.
What is claimed is:
l. A narrow-aisle attachment for use with a lift truck, including:
a load-support tree,
an inner pair of symmetrical arms pivotally attached to the tree,
an outer pair of generally symmetrical arms pivotally attached to the ends of the inner arms, the outer arms being overlapped,
a front plate pivotally attached to the outer pair of arms,
work-engaging means attachable to the plate,
the tree, arms and plate comprising a pivoted six-bar linkage,
rotating means mechanically interconnecting each of the inner arms and the tree to rotate the arms relative to the tree,
latch means selectively interconnecting each of the outer arms to the plate,
means for selectively actuating the latch means,
side-shifter means supporting the tree for selective shifting of the tree transversely to the truck, and
means for selectively actuating the side-shifter means.
2. The invention of claim 1, including:
equalizer means interconnecting the load support tree and side-shifter means to prevent relative twisting therebetween.
3. The invention of claim 1 wherein the rotating means includes hydraulic motors pivotally interconnected between the tree and each of the inner arms.
4. The invention of claim 1 wherein the side-shifter means includes primary means.
5. The invention of claim 4 wherein the means for selectively actuating the side-shifter means includes telescoping primary and secondary motor means.
6. The invention of claim 1 wherein the latch means includes locking cams on the plate which engage catches on the outer arms, and wherein the means for selectively actuating the latch means includes cam-locking fingers which engage the locking cams at selective positions of actuation of the sideshifter means.
7. The improvement in a six-bar linkage type narrow-aisle attachment for use with an industrial truck having a side-shifting mechanism, the improvement providing rotation of the work-engaging means to both sides of the truck, including:
a load-supporting tree operatively attached to the side-shifting mechanism,
the tree providing one link in the six-bar linkage,
an inner pair of symmetrical arms pivotally connected to the tree and providing two links in the six-bar linkage,
an outer pair of generally symmetrical arms, one each pivotally connected to each inner arm and providing two links in the six-bar linkage,
a work-engaging means providing a link in the six-bar linkage,
the outer pair of arms being overlapped and pivotally connected with the work-engaging means,
latch means selectively locking each of the outer arms to the work-engaging means,
means for selectively unlocking the latch means, and
means for pivoting the links.
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