US3477600A - Hinged fork for fork-lift trucks - Google Patents

Description

Nov. 11-, 1969 c. SAWYER 3,477,600

HINGED FORK FOR FORK-LIFTTRUCKS Filed Feb. 6. 1967 2 Sheets-Sheet l INVEN TOR. EDWARD C. SAWYER ATTORNEYS Nov. 11, 1969 c. SAWYER 3,477,600

HINGE!) FORK FOR FORK-LIFT TRUCKS Filed Feb. '6. 1967 2 Sheets-Sheet 2 INVENTOR. EDWARD C. SAWYER ATTORNEY j 3,477,600 HINGED FORK FOR FORK-LIFT TRUCKS Edward C. Sawyer, 9200 River Valley Drive, Brighton, Mich. 4811.6 Filed Feb. 6, 1967, Ser. No. 614,230

Int. 01. B661? 9/16 us. Cl. 214-700 Claims ABSTRACT OF THE DISCLOSURE The fork-lift truck has a verticallymovable carriage and a lifting fork or forks extending outwardly from the carriage. Two pins mount the inner end of each fork on the carriage. If only one pin is' inserted, the fork can oscillate vertically so that it can be worked up and down and gradually inserted under a load. When both pins are inserted, the fork is locked in a substantialy horizontal position for conventional lifting and transfer of the load.

BACKGROUND OF THE INVENTION The invention relates generally to lifting devices and refers more particularly to fork-lift trucks. Heretofore, the forks were rigid. In accordance with the present invention, the forks can be made r'igidfor conventional lifting and transfer of a load, or they can be made free to oscillate vertically so that they can be worked up and down to facilitate the gradual insertion of the forks under the load and the initial partial elevation of the load. While heretofore the rigidly mounted forks could be wedged with difliculty under some loads if not too heavy, the hinged forks of the present invention have a great mechanical advantage due to their fulcruming or levering action, permitting them to be wedged under much greater loads with the power available on the truck.

SUMMARY OF THE INVENTION It is an essential object of the invention to provide a lifting device having a lifting fork (or forks) which can be made rigid for conventional lifting and transfer of a load or which can be made free to oscillate vertically to facilitate the gradual insertion of the fork (or forks) under the load with a fulcruming or levering action.

Another object is to provide a hinge pin and a removable locking pin for the fork.

Another object is to provide the lifting device as a part of a fork-lift truck.

Another object is to provide a fork which can be used as a boom from which a hook may be suspended.

Another object is to provide the lifting device with a single control fork or with two laterally spaced forks, and to taper the ends of the forks to facilitate their insertion under a load.

Other objects and features of the invention will become apparent as the description proceeds, especially when taken in conjunction with the accompanying drawings, wherein:

FIGURE 1 is a perspective view of a fork-lift truck embodying my invention.

FIGURE 2 is a sectional view taken on the line 2-2 of FIGURE 1.

FIGURE 3 is a fragmentary sectional view taken on the line 3-,3 of FIGURE 2.

FIGURES 4 and 5 are diagrammatic views showing how the hinged action of the forks enables them to be gradually worked under a load.

FIGURE 6 is a fragmentary perspective view showing a modification.

FIGURE 7 is a fragmentary side view of the structure in FIGURE 6.

-United States Patent 0 3,477,600 Patented Nov. 11, 1969 "ice FIGURE 8 is a sectional view taken on the line 8-8 of FIGURE 6.

Referring now more particularly to the drawings, and especially to FIGURES 1-5, the reference numeral 10 generally indicates a fork-lift truck having a conventional body 12 and ground engaging wheels 14. Any suitable motor and drive unit may be provided for the operation and movement of the truck.

On the front end of the truck there is rigidly mounted a vertical frame 16 which includes a pair of laterally spaced, vertical uprights 18 connected at the top by a crossmember 20. There is a vertical hydraulic cylinder 22 mounted in fixed position between the uprights. A piston rod 24 extends through the upper end of the cylinder, being connected to a piston 23 reciprocable within the cylinder. A head 26 is mounted upon the upper end of the rod having a pair of freely turning sprockets 28 mounted thereon in laterally spaced relation on horizontal axes. Chains 30 are secured at one end to the upright frame 16 and extend over the sprockets 28. From the sprockets, the chains extend downward and are secured at their opposite or lower ends to the carriage 32.

The carriage 32 comprises a carriage plate 34 which as shown is substantially rectangular and is disposed in a vertical plane for movement up and down on the frame 16. As seen in FIGURE 2, the uprights 18 are in the form of channels opening toward one another. On the rear sides of the carriage plate 34 there are the generally L-shaped retainer strips 36 which engage the adjacent flanges of the channel-shaped uprights 18 to guide the vertical movement of the carriage 32 and prevent it from separating from the upright frame 16.

The carriage plate 34 has mounted thereon a pair of laterally spaced, vertical channels 40 and 42 which are spaced equal distances form and on opposite sides of the center of the plate and open in a forward direction. Each of the channels 40, 42 has in each flange a pair of horizontally spaced holes 44 and 46 at the bottom, and likewise in each flange a pair of horizontally spaced holes 48 and 50 at the top. The holes in the two flanges are aligned.

A pair of elongated forks 52 and 54 are mounted on the carriage 32. The forks are identical. The rear or inner end of each fork has a pair of horizontally spaced holes 56 and 58. The spacing between holes 56 and 58 is the same as the spacing between holes 44, 46 and holes 48, 50.

Two pins are provided for each fork. The number 60 refers to the hinge pin and the number 62 refers to a removable locking pin. Actually both pins may be removable but it is necessary only that the locking pin 62 be removable.

The forks 52 and 54 are shown locked in a substantially horizontal position in FIGURES l and 2. This is accomplished by the insertion of both pins 60 and 62 in the holes 44 and 46 respectively. The pins of course extend through the aligned holes 56 and 58 in the fork. Obviously, the forks could be secured by the pins 60 and 62 in the holes 48, 50 so as to extend substantially horizontally from the upper ends of channels 40 and 42.

When both the hinge pin and the locking pin are inserted to lock the forks 52 and 54 in substantially horizontal position, the forks may be operated in a conventional manner to lift and transfer a load. The cylinder 22 will be operated by hydraulic fluid to extend the piston upwardly so as to elevate the carriage 32 and raise the load. It will be noted that the lower surfaces of the outer or forward ends of the forks 52, 54 are tapered as indicated at 66 in order to facilitate the insertion of the forks under the load.

When an extremely heavy load is to be lifted, it is sometimes extremely diflicult or impossible to work the forks of a conventional truck under the load in the narrow space provided between the floor and the bottom of the load. This is primarily because the forks on conventional trucks are rigidly mounted and therefore are not capable of being levered or fulcrumed so as to take maximum advantage of the available lifting power on the truck.

In accordance with the present invention, the locking pins 62 are removable so that the fork may be oscillated vertically about the hinge pin 60. FIGURES 3, 4 and 5 illustrate the hinge action of the forks when the locking pin 62 is removed. FIGURE 4 illustrates the initial levering action, the load being designated by the reference character L and the fork being shown at 52. Both forks will act together for this purpose. Since the fork is tapered at its outer or forward end, it may be inserted under the adjacent edge of the load. Then, by operation of cylinder 22 to effect an up and down movement of the carriage 32 and with forward traction applied on the wheels of the truck, the forks may be gradually forced under the load. FIGURE 4 shows the manner in which the load may be initially elevated in dotted lines. It will be noted that the fork has a levering or fulcruming action, the fulcrum being at the forward or outer end of the lever. Obviously, a very considerable mechanical advantage is achieved.

FIGURE 5 shows the adjacent edge of the load partially elevated and blocked up by a block 70. The fork may then be further inserted for even greater elevation of the adjacent edge of the load by the operation of cylinder 22 and carriage 32. For this purpose, if desired, a further support 74 may be inserted for the front end of the fork.

After the fork or forks have been forced far enough under the load, the load may be lifted in the usual manner by elevation of carriage 32. In some cases, as where the load is unusually heavy, the load may be strapped to the truck and then dragged or pulled or pushed over the ground while the forks extend under the load and at least partially support it.

FIGURES 6-8 illustrate a modification of the invention in which the fork-lift truck 10 is substantially the same as the one previously described, having the body 12 and ground engaging wheels 14. The upright frame 16 as well as the cylinder 22 and chains for lifting the carriage are also substantially the same. However, the carriage structure itself and including the forks are different. The carriage 80 has a carriage plate 82 which is rectangular and disposed vertically and connected to the lower ends of the chains so that it may be moved vertically with respect to the frame 16 in the same manner as the carriage 32 previously described. As in the previous instance, L-shaped strips 84 on the back of the carriage plate 82 engage the adjacent flanges of the uprights 18 to guide and prevent separation of the carriage from the upright frame.

The carriage includes a centrally located, vertically extending channel 86 which opens in a forward direction. The channel 86 is of considerable length, extending a substantial distance above the carriage plate. Each flange of the channel is provided with pairs of holes 88 and 90, the pairs being spaced apart vertically. The holes of each pair are spaced from one another horizontally. The holes of one flange are respectively aligned with the holes of the other flange to receive the hinge pin 60 and locking pin 62 so as to support the fork 92 at the desired elevation. The fork 92 is shown with its inner end pinned to the lowest set of holes 88, 90 by the hinge pin 60 and the removable locking pin 62. The fork 92 is of the same construction as the forks 52, 54 previously described.

The fork-lift truck shown in FIGURES 6-8 has only the single fork 92 which is centrally located With respect to the carriage. This fork is particularly intended for use in the movement of loads by having them strapped to the lift truck and dragged or pushed or pulled over the floor when the fork is inserted under the load. When operated in this manner, the crosspiece 94 will be removed from the fork. i iie'l The fork 92, when it is desired to elevate a load clear of the ground and transfer it while in that position, will have a crosspiece 94 assembled with it to provide a broader support for the load. The crosspiece 94 is an elongated member having a central through-passage 96 for receiving the fork 92. The crosspiece is thus merely slipped on the fork and may be held thereby a locking pin if desired. In this position, the crosspiece 94 extends at right angles to the fork and is disopsed at any point desired between the ends of the fork. The opening 96 in the crosspiece is shaped to have a close fit with the fork so that by reason of the non-circular cross-section of the fork and the opening, the crosspiece will be held from turning or rotating on the fork.

The reason for providing a plurality of sets of the holes 88, along the length of the channel 86 is to make it possible to mount the fork 92 at any desired position of elevation. For example, if it is desired to move a load from a 4-foot level to a 10-foot level it may be desirable to mount the fork in a set of holes spaced four feet from the bottom of the channel.

The fork 92 can also be utilized as a boom from which a hook may be suspended on a cable. In FIGURE 7, the fork is shown at 92' in the position it might assume as a boom. In this position, the hinge pin 60 is installed as is the locking pin 62, but the locking pin instead of extending through the hole provided in the fork 92, extends under the fork so as to support the fork in the upwardly inclined position shown.

FIGURE 7 also shows the channel in a dotted line position in which it is extended upwardly, with the fork 92 mounted in a set of holes at the upper end of the channel.

It will be understood of course that in connection with the FIGURE 1 form of the invention the channels 40, 42 may be made as long as desired and may even extend to the full height of the channel 86 if desired, depending upon the use that is to be made of the lift truck. It will be also understood in connection with the embodiment in FIGURE 1 that the locking pin 62 may be used to support either or both forks 52, 54 at an incline so that they may serve as a boom in the manner illustrated and described in connection with FIGURES 6-8.

What I claim as my invention is:

1. A lifting device comprising a wheeled vehicle, an upright frame mounted on said vehicle, a carriage movable up and down relative to said frame, power means for moving said carriage, a lifting fork extending outwardly from said carriage, a hinge pin mounting the inner end of said fork on said carriage for vertical swinging, means for selectively locking said fork against vertical swinging in a substantially horizontal position, said locking means comprising a removable pin spaced from said hinge pin, said carriage including an upright having a plurality of vertically spaced pairs of holes, the holes of each pair being spaced apart and adapted to receive said hinge pin and said removable pin to lock said fork in substantially horizontal position.

2. The lifting device defined in claim 1, wherein said holes of each pair are horizontally spaced, the inner end of said fork having holes spaced apart the same distance as said holes of each pair so as to be respectively alignable with the latter holes for the reception of said pins, said fork also being adapted to rest upon said removable pin at an upward inclination to serve as a boom from which a hook may be suspended.

3. The lifting device defined in claim 1, wherein said fork is laterally centered with respect to said carriage, and an elongated support member removably mounted upon and extending at right angles to said fork between its ends.

4. The lifting device defined in claim 1, wherein a second lifting fork extends outwardly from said carriage,

5 6 a second hinge pin mounts the inner end of said second References Cited fork on said carriage for vertical swinging in laterally UNITED STATES PATENTS spaced relation to the first-mentioned fork, and a second 2 469 1 7 5 1949 Wamock et 1 214 7 9 removable pin spaced from said second hinge pin for 2,545,417 3/1951 Ulinski 214-750X selectively locking said second fork against vertical swing- 5 2,558,638 11/1953 ing in a substantially horizontal position, said forks being 32;

equally spaced from and located on opposite sides of the 3,358,863 12/1967 Griffith et X center of said carriage.

5. The lifting device defined in claim 4, wherein the 10 GERALD FORLENZA Pnmary Examiner outer ends of said forks are tapered to facilitate inser- J. SPAR, Assistant Examiner tion under a load to be lifted. L

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