1. Field of the Invention
This invention relates in general to pallet loading and unloading equipment. More particularly, this invention relates to a self-leveling pallet loader and unloader which utilizes a torsion shaft.
2. Discussion of the Prior Art
Customary warehousing operations use wooden pallets to stack goods thereon. The wooden pallets are moved from place to place by means of hand pallet trucks or fork lifts. The pallets take the form commonly known in the industry, wherein the top surface of the pallet is about six inches above floor level. One of the main problems with pallets is the safety of personnel when moving and stacking them. Another problem with palletized shipping or warehousing of products is that there is a tendency for some of the materials when stacked to slide off the pallet.
The problem outlined above has been avoided to some extent by developing a pallet-loading device which utilizes a cradle vertically movable in an enclosure and having a scissors-jack lifting mechanism in each opposing side of the three-sided enclosure. This device has achieved some acceptance, but has been found objectionable because of the lateral instability of the device and enclosure itself. Previous pallet-loading apparatus as mentioned above are typically cantilever-type, support-lifting platforms that have vertically reciprocable and driven movements caused by a hydraulic system housed in the rear wall of the three-sided enclosure. However, one shortfall of such loading devices is that due to the cantilever suspension, any imbalance in loading forces from the center of the loading platform will nevertheless cause a tilting of the platform. Such tilting of the platform is non-desirable and, depending on its severity, could even be catastrophic. Therefore, there is a need for a hydraulically driven three-sided enclosure device wherein any off balance in the loading forces operating upon the platform of said device, can be effectively and efficiently transferred such that no tilting in the lateral direction will be experienced by said device.
A primary object of the present invention is to provide an open-topped, three-sided enclosure in which tiers of goods stacked on a pallet may be prevented from spilling or sliding from the pallet due to an imbalance on either the pallet or on the platform of the three-sided enclosure.
Another object of the present invention is to provide a pallet lift apparatus in which the lift platform is a cantilever support structure, wherein an imbalance in loading on said structure is corrected such that none of the goods that are stacked on the pallet will spill or slide from said pallet.
An object of the present invention is the elimination of a separate provision for preventing reverse tilt.
A further object of the invention is improved safety and convenience of operation.
A further advantage of the invention is a substantially rigid platform when subjected to laterally eccentric loads.