Dunnage Clamp For Forklift Trucks

Abstract

An auxiliary fork arrangement is disclosed in connection with forklift trucks for clamping and transporting dunnage simultaneously with the carrying of a load, especially of piles of lumber. Hydraulic actuators are incorporated into the lifting carriage for moving the auxiliary fork members laterally relative to the main forklift members so that any dunnage boards or planks which are inserted under a stack of lumber or other load may be firmly clamped between the main and auxiliary fork members prior to lifting the load and carrying it to its desired location. When the load is deposited at the new location, the dunnage members are then in the desired position under the load. The actuators are then caused to move the auxiliary fork members away from the main fork members, thereby releasing the dunnage members, and the truck can then withdraw the fork members from beneath the load.

Description

BACKGROUND OF THE INVENTION

Forklift trucks are commonly used for moving sawed lumber and other similarly stacked material. In connection with this moving it is necessary that space be provided beneath the stacks of lumber to enable the forks to be placed under the lumber in order that it may be lifted by the forklift truck and carried to a desired location. Similarly, at the new location where it is desired to deposit the lumber it is necessary that space be provided so that the forks may be withdrawn from the stack. This space has usually been provided by means of dunnage boards arranged transversely to the pile of lumber which are of sufficient thickness to permit the fork to be inserted under the load. Typically such boards might be 4 inches .times. 4 inches. In moving such piles of lumber, it has normally been necessary for a man other than the forklift truck driver to pick up these boards and replace them at the new location before the load is deposited. This obviously requires the services of an extra man and is wasteful of labor.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing the front portion of a forklift truck with the lift carriage, main lift forks and auxiliary dunnage carrying means according to the invention.

FIG. 2 is a plan view taken from the front of a carriage structure essentially the same as that shown in FIG. 1.

FIG. 3 is a sectional view taken along line 3--3 of FIG. 2.

FIG. 4 is a plan view of a modification of the dunnage carrying means shown in FIGS. 1, 2 and 3.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to FIG. 1, a partial perspective view of a forklift truck 10 is shown with the rear portions broken away since they are unrelated to the invention. The truck body 11 is supported on wheels 12, and attached to the body is a carriage structure 14 which is movable vertically by means, not shown, which are conventional in the art. This carriage which may be of any desired height depending on the load requirements, is shown broken away at the top. Attached to the carriage structure 14 are main lift fork members 16 and 18 which are normally driven under the load 20 so that the load may be raised from the supporting surface and transported by means of the truck. In this instance, the load is shown as a stack of lumber including boards 20a, 20b and 20c. The load could also be in the form of a large carton or a stack of longitudinally arranged material such as pipe. Positioned beneath the load in such manner as to raise the load off of the supporting surface are a pair of dunnage boards 22 and 24. It is necessary that the load be supported in this manner to enable the fork members 16 and 18 to be inserted under the load without damage thereto. Smaller auxiliary fork members 26, 28 are positioned adjacent the main fork lift fork members 16 and 18 and are movable transversely along bars 30 and 32 by hydraulic means as described below. The main and auxiliary fork members will normally include bushings or other bearing means in contact with bars 30 and 32. The auxiliary fork members, being short, are nevertheless very rugged and capable of supporting substantial weight.

Much of the detail in connection with the carriage shown in FIG. 1 will become more apparent from considering FIG. 2. The carriage 14 consists essentially in a large rectangular frame structure of steel box section members, often approximately 8 inches .times. 8 inches, around the top and two sides thereof. The bottom frame member 34 is a solid piece which is set back relative to the face of the box sections and serves as a track along which the fork members may be moved laterally and supported thereon as by means of rollers 36 and 38 on the main fork members and rollers 40 and 42 on the auxiliary fork members. In order to facilitate loading of stacks of different widths, means are provided on the carriage consisting, in this instance, of large hydraulic actuator members 44 and 46 which are operative through rods 48 and 50, respectively, to shift the main fork members 16 and 18 laterally relative to each other. Side shift means may also be provided for moving the carriage laterally with respect to the truck to facilitate loading where centering of the truck relative to the load is difficult. The truck itself can support a somewhat unbalanced load relative to its center axis, but the load itself may need to be rather evenly supported on the main fork members 16 and 18. Side shift means are conventional and have not been shown in detail.

Attached to fork members 16 and 18 are brackets 52 and 54, respectively, which support additional hydraulic actuators 56 and 58. The actuating rods 60 and 62, respectively, of actuators 56 and 58 are fastened to bracket members 64 and 66 which are, in turn, welded or otherwise suitably attached to the auxiliary fork members 24 and 22, respectively.

From the above description, it will be apparent that the actuator 44 may move the main fork member 16 and auxiliary fork member 24 together laterally along the track formed by the surface of solid member 34 and on rollers 36 and 40. Similarly, actuator 46 can move main fork member 18 and auxiliary fork member 22 laterally on rollers 38 and 42. The actuator 56 is capable of moving auxiliary fork member 24 laterally with respect to main fork member 16 in such manner that the dunnage may be clamped between members 24 and 26 as shown in FIG. 1. Similarly, actuator 58 is capable of moving auxiliary fork member 22 toward or away from main fork member 18, as described. It will be recognized that a number of interconnecting hydraulic conduits or hoses will be required to operate the described actuators, but these have been left out of the present description for clarity. The manner of making these connections is, of course, well within the skill of the art. If required, an accumulator may be included in the hydraulic system to compensate for leakage and to provide reserve power for such operations as straightening and clamping the dunnage after the load has been taken by the main fork members.

FIG. 3 shows a somewhat enlarged sectional view taken along line 3--3 of FIG. 2. Main fork member 16 is fastened to the carriage 14 by means of a collar structure 16a which is welded to the fork member and which slides along rod 30. In this view, one sees the end of a box member 48a to which the rod 48 is attached for effecting lateral movement of the fork member 16. This view also shows a section of actuator 56 and the box-like supporting structure 52. The roller 36 is shown at the back of main lift fork member 16 and in contact with the transverse track member 34. The carriage 14 may be made to tilt, and a bracket 67 is welded to the back of fork 16 to insure that it does not swing away from track member 34. Positioned above member 34 is a cylindrical member 68 which is a pivot pin forming part of a mechanism enabling the entire carriage 14 to be pivoted. This pivot member 68 and a cooperating bracket 70 which receives an upper pivot member, not shown, form no part of the present invention other than as a part of the overall environment.

FIG. 4 shows a plan view, partly broken away, of a modified form of dunnage clamp. After a significant amount of use, the bushings in the "eyes" of the dunnage clamps 26 and 28 sliding on rods 30 and 32 may become worn so that member 26, for example, tends to splay outwardly with respect to the main fork member 16. Clamping the dunnage member 24 between forks 16 and 26 will then result in supporting the member 24 only at the inside end, permitting the outboard end to drop and perhaps to drag on the supporting surface. To compensate for such wear, the outboard end of fork member 26 may be formed with indentations 72 and 74 separated by a boss 76 to which a shoe member 78 is pivotally attached by means of a pivot pin 80. With proper location of pivot pin 80, the shoe 78 will contact the dunnage board 24 even though the end of the fork member 26 is splayed outwardly somewhat relative to main fork member 16.

It will be apparent to those skilled in the art that the invention described herein is applicable to forklift trucks of any size. It obviously is applicable to trucks having no side shift mechanism. Obviously the auxiliary fork members may be operated by means other than hydraulic actuators such as electric motor means, particularly with a large gear reduction, but since most forklift trucks have available a source of hydraulic fluid under pressure for the lift mechanism, the hydraulic actuators are perhaps most conveniently utilized. And while the auxiliary fork members need not necessarily move with the main fork members, it is most convenient to have them do so since the travel required of the corresponding actuators and the time required for actuation would be reduced.

Claims

I claim:

1. For use with forklift trucks having a carriage movable transversely with respect to its supporting means on said truck and main fork members on said carriage for lifting a load which is held a short distance off the supporting surface by means of dunnage members arranged approximately parallel to said fork members, dunnage carrying means comprising:

auxiliary fork members on said carriage positioned adjacent each of said main fork members, one of said main and auxiliary fork members including a shoe member pivotally attached at the edge nearest its adjacent fork member, and

power operated means operable to move said auxiliary fork members transversely with respect to said carriage toward said main fork members to thereby clamp said dunnage members between said main and auxiliary fork members such that said dunnage members will be moved with said load.

2. Dunnage carrying means as set forth in claim 1 wherein said auxiliary fork members are substantially shorter than said main fork members.

3. Dunnage carrying means as set forth in claim 1 wherein said auxiliary fork members are positioned toward the outside of said main fork members and are moved inwardly to clamp said dunnage members and outwardly to release said dunnage members.

4. Dunnage carrying means for a forklift truck having a vehicle body,

a carriage attached to said body,

lift fork members supported on said carriage,

and power operated means for moving said lift fork members vertically for enabling a load to be lifted and transported comprising:

auxiliary fork members on said carriage positioned adjacent to each of said lift fork members, said auxiliary fork members being substantially lighter and shorter than said lift fork members, and one of each pair of said lift and auxiliary fork members including a shoe member pivotally attached at the edge nearest its adjacent fork member, and

power operated means operable to move said auxiliary fork members transversely with respect to said lift fork members to clamp said dunnage between said auxiliary and lift fork members.