US3182836A - Push-off attachment for lift trucks - Google Patents

Description

5. w. SINCLAIR PUSH-OFF ATTACHMENT FOR LIFT TRUCKS May 11, 1965 3 Sheets-Sheet 1 Filed Jan. 6, 1964 llllh.

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May 11, 1965 s. w. SINCLAIR 3,182,836

PUSH-OFF ATTACHMENT FOR LIFT TRUCKS Filed Jan. 6, 1964 3 Sheets-Sheet 2 Jfuarf W. J//7/0// INVEN OR. m 41 W QM 52,11 AX/2%,???

May 11, 1965 S. W. SINCLAIR PUSH- OFF ATTACHMENT FOR LIFT TRUCKS 3 Sheets-Sheet 3 Filed Jan. 6, 1964 ,URE 1,

United States Patent 3,182,836 PUSH-OFF ATTACENT FOR LIFT TRUCKS Stuart W. Sinclair, Houston, Tex., assignor to Anderson,

The present invention relates to push-off attachments for lift trucks, and more specifically to a push-off attachment for use in removing a load from the tines of a fork lift truck, and improvements in the construction thereof.

In the past, push-off attachments have been either of the lazy tongs arrangement, a parallelogram arrangement orof the horizontal slide arrangement. Examples of these prior structures are found in the US. Patent Nos. 2,993,610; 2,619,241; 2,672,269; and 2,590,355. With the first two types, the sagging of the pusher plate, particularly when it is extended, has been somewhat of a problem. In the last type, the bulk and length of the device have presented maneuverability problems. It is an object of the present invention to overcome the foregoing disadvantages of the prior art structures in a manner not previously contemplated.

Another object of the present invention is 'to provide 7 Yet another object of the present invention is to provide a push-off attachment whichincludes pivoted yokes and pivoted equalizers set at 90from the yokes, so as to prevent sagging of the pusher plate when fully extended, and at the same time allows the attachment to be folded into a very small unit when thepusher plate is retracted.

A still further object of the present invention is to provide a push-off attachment which includes hydraulic motor means for actuation thereof, whichtmotor means may be placed in such a position that it does not substantially increase the overall width of the attachment when the pusher plate is fully retracted. A particular advantage of this arrangement is that it allows the pusher plate to be shifted horizontally by means of other typical lift truck attachments, thus increasing the overall versatility of the unit. e

A. further object of the present invention is to provide extends and retracts the pusher plate in exact proportion to the volume of fluid in the motor, so that movement of the pusher plate is uniform.

Other further objects, features and advantages will be apparent from the following description of presently preferred embodiments of the invention, given for the purpose of disclosure, taken in conjunction with the accompanying drawings, where like character references designate like parts throughout the several views and where: V V

FIGURE 1 is aside View of a lift truck which includes the present invention thereon in the act of discharging aloadfrom the fork tines, V

FIGURE 2 is an enlarged partial side view, partially in section, showingiindetail the attachment of FIG- FIGURE 3 is a top view, partially in section, of the attachment of FIGURE 2, V

FIGURE 4 is a front view, partially in section, of the :attachment of FIGURE 2, Q

a a push-off attachment wherein the hydraulic motor means 3,182,33 Fatentecl May 11, 196

FIGURE 5 is a side view, similar to FIGURE 2, of modification of the present attachment, and

FIGURE 6 is a side view showing the attachment FIGURE 5 when retracted.

The invention generally comprises a frame, a pair hinged or pivoted yokes, a pair of hinged or pivote equalizers set at from the yokes, and means for e: tending and retracting a pusher plate relative to the frami Referring now to the drawings, and particularly 1 FIGURE 1, the reference numeral 19 generally refer to a conventional fork lift truck which includes a ma; 12 to which are attached vertically movable fork tines 1 by means of the bracket 16. In such trucks 10, mear 18 are conventionally provided for raising and lowerin the tines 14. Attached also to the bracket 16 is the pusl off attachment 20 of the present invention, which will t described in greater detail hereinafter. Generally, hov ever, the push-off attachment 20 includes the vertic: pusher plate 22 which may be horizontally traversed rel; tive to the mast 12, so that a load 24 carried on the tint 14 may be pushed off or pulled on the tines by the li: truck 10. Although not shown, the pusher plate 22 ma have various pallet grippers mounted thereon to expan the use of the lift truck 10, in a manner similar to'thos illustrated in the patents previously mentioned. As suc pallet grippers form no part of the present invention, the are not illustrated.

Referring now to FIGURE 2, the push-off attachmei 26 will be explained in greater detail; Attached to tl bracket 16, in any suitable manner such as by welding, 21 frame 26. Pivotably attached to the frame 26 is a re; yoke 28, and pivotably attached to the rear yoke 28 is tt front yoke 30. In turn, the front yoke 39 is pivotably at tached to the pusher plate 22. The pivotable attachmen in each instance are all parallel, here shown as horizonta and include the hinges 32, 34 and 36 respectively.

With reference now to FIGURES 3 and 4, it will t noted that both the rear and frontyokes 28 and 30 get erally resemble large letter Cs which are joined back 1 back by means of a group of three hinges 34, while tl extended ends of the yoke are joined respectively to tl: frame 26 and plate 22 by a pair of hinges 32 and 36. A though three pairs of hinges 34 are shown, this is a me] matter of convenience and a greater or smaller numb: may be utilized. It is to be particularly noted that t! hinges 32 are parallel to the hinges 34 and that the hingi 34 are parallel to the hinges 36, consequently the plate 2 will be parallel to the frame 26 at all times.

Referring again to FIGURE 2, pivotably attached 1 the frame 26 is a rear equalizer 38, and pivotably attache and are here shown as the vertical hinges 42, 44 and 4 respectively.

As can be seen by comparing FIGURES 2, 3, and the hinges 42, 44, and '46 are all parallel, consequentl the pusher plate '22 is prevented from dropping or sa, ging with reference to the frame 26. Furthermore, sinr the equalizers 38 and 40 are ,mounted at right angles '1 the yokes 23 and 3%, it is apparent ,th atzthe hinges 32 at 42 define a plane which is parallel "to the plane define by the hinges 36 and 46. A further plane is defined t the h inges 34 and 44, which is likewise parallel to tl previously mentioned planes. Consequently, the push plate 22 is held vertically and parallel to the mast 1 no matter what its extension from the frame 26.

Because the front and rear yokes 28 and are t shaped, it is possible for the pusher plate 22 to be grea ly retracted and for the folded equalizers 38 and at to 2 within the open ends of the yokes so that the entire a tachment 22 forms a very-compact unit. Thus, as sec in FIGURE 3, the length of either equalizer 38 or 4 ess than the distance between the ends of either yoke or 30. With reference again to FIGURE 2, the reference nural 48 generally refers to the means for traversing or acting and extending the pusher plate'22, and is here wn as a hydraulic motor. The hydraulic motor genlly consists of a cylinder 50 having a piston 52 slidy mounted therein. The cylinder 50 is attached to the r yoke 28 by means of a bracket 54 and pivotable con- :tion 56 on the plate 70. The piston 52 is attached the front yoke 30 by the connecting rod 58 and pivote connection 60 on the lug 72. Fluid pressure supmeans 62 and 64 are connected to the cylinder 50 that hydraulic fluid may enter therethrough to recipate the piston 52 within the cylinder 50. As can be n in FIGURE 3, a pair of identical means 48 are proed, although it would be well within the skill in the to delete or add additional units. the pusher plate 22 generally comprises a flat plate ose outer edges 66 are turned back, thereby forming generally rectangular pan. When the pusher plate 22 fully retracted, the rolled back edges 66 cover the opting mechanism as an additional safety advantage. th reference particularly to FIGURE 4, it will be noted vt there are several cut outs 68 in the front of the plate in order that the hinges 34 and 36 may extend thereough. In this manner, when the plate 22 is fully rected, the over-all width of attachment 249 is reduced. With reference again to FIGURE 2, the double-headed ow immediately above the plate 22 shows the direcnal movement of the plate relative to the frame 26. ren fully retracted, the plate 22 is shown in dotted lines 22'. In a similar manner, the double-headed arrow we the means 48 shows the relative movement of the ans when retracting and extending the pusher plate 22. e retracted position of the means 48 is shown in dotted as as 48'. [t is to be noted that the particular disposition of the ans 48 is such that similar triangles are produced. at is to say, that the triangle formed with its apex as hinge 34 and its two legs terminating at the hinges and 36 is similar to the triangle with its apex 34 and two legs terminating at the pivotable connections 56 i 60. Consequently, the reaction of the means 48 on smaller similar triangle produces a linear proportionmovement in the yokes 28 and 30, and therefore the sher plate 20. In this manner, advantageously, the esent invention provides a push-off attachment wherein movement of the pusher plate 20 is directly propornal to the volume of fluid introduced into the cylinder so that'the operator need not make adjustments to in-tain a uniform traverse speed. [n use, the fork lift truck 10 is maneuvered until the 'k tines 14 may be inserted beneath the load 24. ereupon, the pusher plate 22 may be retracted against mast 12 by inducing hydraulic fluid through the fluid :ssure means 64 to activate the piston 52, which in turn tws the connecting rod 58 into the cylinder 50, thus iwing the pivotable connections 56 and 60 together. is in turn draws the hinge 36 towards the hinge 32, :reby retracting the pusher plate 22 against the frame to the position shown as '22 in FIGURE 2. At this re, or simultaneously with the previously described tion, the truck maybe moved forward so that the tines under the load 24 thereby allowing the truck 16 to lift load and maneuver it to any desired position. To remove the load 24 from the tines 14, fluid i in ced through the fluid pressure means 62, thereby pushthe piston 52 and the connecting rod 58 so that the 'otable connections 56 land 60 are moved apart. This turn causes the hinge 36 to move away from the hinge thereby extending the pusher plate 22. Atv the same is, the combination of the yokes 28 and 30 and the ualizers 33 and t prevent the pusher plate 22 from sagging and maintain it in a position which is .at all times parallel to the frame es.

With reference now to FIGURES 5 and 6, a modification of the device shown in FIGURE 2 is illustrated, wherein the majority of the various elements are substantially identical to those previously described, and hence have been given identical numbers. In this modification, it will be noted that the means 48 is aligned substantially vertically instead of horizontally as in FIG- UR-E 2. The particularly advantageous result obtained thereby is seen in FIGURE 6, wherein it will be noted that the means 48 remains substantially vertical and does not extend any great distance behind the frame 26 as does the comparable means 48' in FIGURE 2.

It should be further noted when comparing FIGURES 5 and 2 that the cylinder 5t? is attached to the front yoke 36 and connecting rod 58 is connected to the rear yoke 28 in FIGURE 5, while the parts are reversed in FIGURE 2. In any event, it is to be noted that the same similar triangles as shown in FIGURE 2 exist in FIGURE 5 such that the triangle formed by the hinges 74, '76, and 34 is similar to the triangle formed by the hinges 32, 36, and 34. Consequently, the same linear motion produced by the device of FIGURE 2 is produced by the device of FIG- URE 5. Said another way, the similar triangles of FIG- URE 5 have merely been rotated, but still remain similar and in addition to providing the same function as before, advantageously allow the cylinder 50 to be mounted more compactly.

As before, the means 458 for traversing or retracting and extending the pusher plate 22 is here shown as a hydraulic motor. The hydraulic motor generally consists of a cylinder 54} having a piston 52 slidably mounted therein. The cylinder 50 is attached to the rear yoke 28 by means of a bracket '78'and pivotal connections 76 on the lug 86 which forms a part of the yoke 30. The piston 52 is attached to the rear yoke 28 by the connecting rod 58 and pivotal connection 74 on the plate 82 which forms a part of the rear yoke 28. Fluid pressure supply means 34 and 86 are connected to the cylinder 50 so that bydraulic fluid may enter therethrough to reciprocate the piston 52 within the cylinder 50. Just as was shown in FIGURE 3, a pair of identical means 48 may be provided, although it would be well within the skill in the art to delete or add additional units.

Upon the introduction of hydraulic fluid to the cylinder 50, the movement of the hinge 34' and the pusher plate 22 respectively are shown relative to the frame 26 by the double-headed arrows above these items. Thus, upon the introduction of hydraulic fluid through the supply means 84, the piston 52 is activated and the pivotal connection 74 is pushed further from the pivotal connection 76, thus resulting in traversing the pusher plate 22 by extending it from the frame 26 by means of the reaction on the rear and front yokes 28 and 3%. To retract the pusher plate 22, hydraulic fluid is introduced through the supply means 86, thus pushing the piston 52 within the cylinder 50 and drawing the pivotal connections 74 and 76 together, which in turn react upon the rear and front yokes 28 and 30. The position of this modification when fully retracted is shown in FIGURE 6. The use of the traversing of the pusher plate 22 of the modification shown in FIGURES 5 and 6 is identical to that described hereinabove with reference to FIGURES 1-4.

Thus, advantageously, the present invention has provided :a push-off attachment which is quite rigid, even when fully extended, and which folds into a small unit adjacentto the lift truck body when retracted, as well as providing the other advantages previously mentioned.

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 presently preferred embodiments of the invention have been given forrthe purpose of disclosure, numerous changes in the details of construction, and the combination, shape,

size, arrangement of parts and uses may be resorted to without departing from the spirit and scope of the invention as hereinafter claimed.

.What is claimed is:

1. The combination with a fork lift truck having a vertically movable bracket of apush-ofi attachment including:

a vertical frame attached to the bracket, a first C-shaped yoke, a second C-sh'aped yoke, the yokes pivotally connected back to back, a vertical pusher plate, the ends of the first yoke horizontally pivotally connected to the frame, the ends of the second yoke horizontally pivotally connected to the pusher plate, a first equalizer, a second equalizer, the equalizers pivotally joined, the first equalizer vertically pivotally connected to the frame, the second equalizer vertically pivotally connected to the pusher plate, a hydraulic motor including a cylinder and a piston, the cylinder pivotally connected to one of the yokes,

. each yoke.

3. The invention of claim 1 wherein the cylinder i mounted substantially horizontally.

4. The invention of claim 1 wherein the cylinder i mounted substantially vertically.

References Cited by the Examiner UNITED STATES PATENTS 2,787,393 4/57 Horton 2l45l 2,975,923 3/61 Ulinski 2l4-514 I FOREIGN PATENTS 122,075 2/59 U.S.S.R.

HUGG O. SCHULZ, Primary Examiner.

GERALD M. FORLENZA, Examiner.

Claims (1)

1. THE COMBINATION WITH A FORK LIFT TRUCK HAVING A VERTICALLY MOVABLE BRACKET OF A PUSH-OFF ATTACHMENT INCLUDING: A VERTICAL FRAME ATTACHED TO THE BRACKET, A FIRST C-SHAPED YOKE, A SECONS C-SHAPED YOKE, THE YOKES PIVOTALLY CONNECTED BACK TO BACK, A VERTICAL PUSHER PLATE, THE ENDS OF THE FIRST YOKE HORIZONTALLY PIVOTALLY CONNECTED TO THE FRAME, THE ENDS OF THE SECOND YOKE HORIZONTALLY PIVOTALLY CONNECTED TO THE PUSHER PLATE, A FIRST EQUALIZER, A SECOND EQUALIZER, THE EQUALIZERS PIVOTALLY JOINED,

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