Load clamping plate

A clamping plate assembly for movement laterally into and out of engagement with a load includes a main plate member which has front, rear, upper and lower edges. Along the lower edge of the main plate member, an auxiliary plate overlies a portion extending from the lower edge a predetermined distance toward the upper edge thereof, and is removably attached to the main plate member. A yieldable friction material then is over substantially the major portion of the auxiliary plate and the portion of the main plate member not covered by the auxiliary plate.

BACKGROUND

This invention is in the field of industrial lift trucks which employ oppositely disposed load-clamping plates actuated toward and away from each other to clamp a load therebetween for lifting and transporting the load. When the load is transported to the location desired, the load clamping plates are moved away from one another to release the load.

DETAILED DESCRIPTION

Reference now should be made to the drawings, in which the same reference numbers designate the same or similar components throughout-the different figures. As illustrated generally inFIG. 1, an embodiment of the invention is shown as used in conjunction with an industrial lift truck.

The lift truck10shown inFIG. 1is designed to move a pair of oppositely disposed load clamping plates, including main plates16and18, laterally toward and away from one another on mechanism14, generally illustrated inFIG. 1, and vertically on additional mechanism12, as shown inFIG. 1. The details of operating the assembly shown inFIG. 1to effect the movement of the mechanisms12and14are not provided here, since those mechanisms are well known and are widely used in conjunction with industrial lift truck machines. In addition, the plates16and18, employed with the lift truck10shown inFIG. 1, are of the size typically used with such industrial lift trucks, generally on the order of 4′ by 4′, or 4′ by 3′. Some specialized applications may be significantly smaller or larger.

In operation, the plates16and18are moved adjacent the opposite sides of a stack of cartons or similar load (not shown), and then are moved toward one another to squeeze the stack of cartons to thereby allow the carton stack to be lifted by the mechanism12. The carton stack then may be transported to a desired location. The mechanism12then is operated to either raise or lower the stack of cartons to a desired position. Finally, the plates16and18are moved away from one another laterally to allow the stack of cartons to be placed in a warehouse or truck, or other desired location.

In the embodiment shown inFIGS. 1 through 8, the facing surfaces of the main plate members16and18have yieldable friction material20bonded or attached to them. This material20may be rubber or rubber-like material having raised portions20A separated by parallel grooves20B extending from front to back, as illustrated most clearly inFIG. 4.

Rubber facings or other frictional rubber-like materials have been used to coat the facing surfaces of main plate members, such as the members16and18in the past. Typically, however, these surfaces undergo significant wear of the rubber coating along the lower front edge, and extending a substantial distance upward toward the upper edge of the main plates. If a significant exposure of the surface of the coated plate (which typically is made of aluminum) occurs, the slippage of a load which is squeezed between the plates frequently takes place. This is dangerous, and in the past the entire clamping pad assembly (including the large aluminum plates and the rubber coated surfaces) were replaced. Prior to replacement, it has been the practice in some environments to turn the clamping plates upside down; so that the upper edge now becomes the lower edge; and vice versa. When the significant wear once again occurs on the lower edge, the plates then typically have been discarded and replaced with new ones.

In the embodiment shown inFIGS. 1 through 8, the assembly described in the previous paragraph has been modified by attaching a separate, elongated, rectangular auxiliary plate22(most clearly shown inFIG. 2) to the main plate16or18. The lower edge of the plate-22is parallel to the lower edge of the main plate16or18, and the rear edge terminates in the plane of the rear edge of the main plate16or18.

The front or forward edge of the auxiliary plate22terminates a slight distance toward the rear of the front edge of the main plate16or18, as shown most clearly inFIG. 5. In the space between the front edge of the auxiliary plate22and the front edge of the main plate16or18, a nose piece or shoe26, having a beveled front edge (again as shown most clearly inFIGS. 4 and 5), is attached. As shown inFIG. 5, this attachment of the nose piece26is effected through recessed holes38by means of bolts36, which engage tapped holes40(or recessed nuts secured into the exposed or outer surface of the plates18or16) to firmly hold the nose piece or shoe26in place on the surface23of the plate16or18adjacent the front edge of the auxiliary plate22. This assembly is shown most clearly inFIGS. 4 and 5, withFIG. 5illustrating the details of the manner of this attachment.

It should be noted that the bolts36through the nose piece26do not extend through the exposed surface of the main plate16or18; and the head of the bolts36are below the exposed surface of the nose piece26in the recesses38, as shown most clearly inFIG. 5. It also should be noted that the nose piece26is tapered from the front edge outwardly to the upper surface, again as shown most clearly inFIGS. 4,5and8. As shown inFIGS. 5 and 8, the manner in which the nose piece fits over the front edge of the auxiliary plate22is by means of a recess29having a thickness equal to the thickness of the plate22.

The remainder of the surfaces of the main plate members16and18and the surface of the auxiliary plate22, located to the rear of the nose piece26, are coated with yieldable friction material20, preferably (but not necessarily) in the form of rubber or rubber-like material having resilient compressible characteristics. In order to improve the resiliency and to prevent compression from hardening the yieldable material, the rubber or rubber-like material is provided with elongated parallel grooves20B extending from the front to the back, or from the front edge to the rear edge, of the main plate member16or18and the corresponding auxiliary plate22, as illustrated in detail inFIG. 4and in enlarged detail inFIG. 3.

The grooves or channels20B are located between upper surfaces20A as shown most clearly inFIG. 8. Consequently, when pressure is applied through a squeezing action of the movement of the plates16and18toward one another to engage a load, the material20A is compressed and is permitted to expand into the area of the grooves20B in the relaxed or uncompressed condition shown inFIG. 3. This permits substantial resiliency; and once the load is released, the material is selected to rebound to the original configuration shown inFIG. 3. In place of elongated grooves20B, circular depressions or cylindrical columns could also be used, as well as other configurations.

As illustrated inFIG. 5, the vertical thickness of the rubberized material20A is selected to be slightly above the upper plane of the nose piece26. Consequently, upon engagement of the clamping plates16and18with a load, the rubber or rubber-like material20which covers the auxiliary plate22is compressed along with compression of the material20which overlies or covers the remainder of the facing surfaces of the main plate members16and18.

Typically, the main plate members16and18have a thickness on the order of ⅜″ or greater; and the backing plate22has a thickness of approximately ¼″ or greater, with a vertical height or width of approximately 8″. This dimension is by way of example and it may vary to be more or less than 8″. The material20then has a thickness of the portion20A which is greater than ¼″ and may extend to a thickness of 1¼″. For example, a thickness of ⅝″ over the exposed facing surfaces of either of the plates16or18, and with a thickness of ⅜″ or greater over the surface of the auxiliary plate22has been found suitable. The overall thickness of the rubber or rubber-like coating20is selected so that the plane of the upper surfaces of the portions20A, which overlies the auxiliary plate22as well as the remainder of the surface of the main backing16and18, is all in the same plane.

By providing the auxiliary plate22with a separate rubberized coating from the coating which covers the major portion of the remainder of the main plate members16and18, any excessive wear which occurs, as mentioned above, typically on the lower edge of such plates, will occur on the rubberized portion overlying the auxiliary plate22. If excessive wear should occur in this region, bolts30which extend through recessed holes32in the plate22(to removably secure the plate22to the main plate members16or18), may be removed; and the plate22, with the rubberized coating20on it, is removed and replaced with a new coated auxiliary plate22. This auxiliary plate22is a relatively small portion of the mass of the overall assembly, and yet this is the region where wear most frequently has occurred in the past. Consequently, by replacing only this portion of the entire assembly, the composite assembly enjoys a significantly extended life. In addition, the utilization of the nose piece26reduces wear which, in the past, has occurred at the lower facing corners of clamping plates like the plates16and18of such assemblies. If the nose piece26should somehow itself become damaged, it is readily replaced by removing the bolts36shown inFIGS. 4 and 5, and then reassembling a new nose piece26with the bolts36in the manner described above.

The foregoing description of embodiments of the invention is to be considered as illustrative and not as limiting. Various changes and modifications will occur to those skilled in the art for performing substantially the same function, in substantially the same way, to achieve substantially the same results without departing from the true scope of the invention as defined in the appended claims.