This invention lies in a highly developed area of the art relating to apparatus for facilitating the loading and unloading of vehicles and the handling of loads within the confines of the vehicles. For the most part, the prior art apparatus provides means whereby loads are actually lifted off of the supporting surface and transferred either into or out of the vehicle. Accordingly, the power and structural requirements of such apparatus are extremely high if the apparatus is to operate efficiently for any substantial period of time. The purpose of this invention is to provide a more simplified apparatus for loading and unloading vehicles having minimum power and structural requirements.
Under the general concept of the invention, power-driven cables are stretched over the vehicle floor from front to rear and are movable in either direction in unison. A plurality of cables are used and spaced laterally of the vehicle. The number of cables which are to be used depends upon the size and type load to be handled. The loads are placed directly on the cables and the cables are actuated to shift the loads from front to rear or vice versa as the case may be. The cables ride on the vehicle floor, however, the frictional contact is only a line contact and is substantially less than the contact which would occur if the loads were placed directly on the floor.
The invention disclosed herein is an improvement over prior art arrangements primarily in the drive system employed and in the manner in which the cables are installed in an existing vehicle without any significant modification to the vehicle.
At least two others in the prior art have patented generally similar systems for vehicles. U.S. Pat. No. 3,272,358, entitled TRUCK UNLOADING STRUCTURE, dated Sept. 13, 1966, to F. Thompson. Thompson discloses the general concept of using cables on a vehicle floor to shift loads therein. However, his arrangement has little utility except for relatively small loads. Thompson employs a plurality of endless cables stretched over a friction surface roll and idlers rolls. The friction roll is driven by a suitable power source. It is quite apparent, however, that the frictional contact between the roll and cable would not be sufficient to move loads of any appreciable size and weight. Further, Thompson's particular arrangement of pulleys for supporting the cables is unsuitable for use in trailers having fifth wheel assemblies thereon. In U.S. Pat. No. 2,815,874 to Kowal, a drive system more positive than that of Thompson is employed. Endless chains drive a bulkhead which in turn drives the cables. However, the drive system and cable arrangement of Kowal would require modification of the understructure of the vehicle and makes no allowance for a fifth wheel connection.
Further, this invention constitutes an improvement over the arrangement disclosed in applicant's copending application Ser. No. 543,608, filed Jan. 23, 1975, now abandoned, entitled LOADING AND UNLOADING APPARATUS FOR VEHICLES.
Other arrangements found in the prior art use movable flexible planar sheets or floors covering substantially the entire area of the vehicle load-supporting floor. The sheets are wound onto takeup reels positioned on the vehicle. The deficiencies of such arrangements are quite apparent in that use of such movable sheets or the like provides no relief from substantial frictional contact with the underlying floor of the vehicle.
The movable sheet-type arrangements are cumbersome and do not lend themselves to ready adaptability to existing truck bodies, and are likewise unsuitable for use with trailers having fifth wheel coupling assemblies. Also, such arrangements generally render the vehicle inoperative for loading or unloading by using a forklift truck, for example, wherein the truck must enter the vehicle. The cables in the invention do not impede the movement of a forklift across the vehicle floor nor will they be damaged thereby.