Abstract:
A wheeled elevator platform for use in loading and unloading highway trucks from and to a loading dock at a merchandise storage facility. The elevator includes folding ramps, hydraulically operated lifting arms to raise and lower the elevator platform, a plurality of screw jacks to level the platform, and bumpers to absorb the forces of a truck accidentally colliding with the apparatus.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     Not Applicable 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not Applicable 
     REFERENCE TO A MICROFICHE APPENDIX 
     Not Applicable 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a wheeled elevator platform used to load or unload freight onto or from a highway truck; and more particularly, it relates to such a platform that may be employed where the unloading dock is not deep enough to support an elevator platform apparatus and yet an elevator is needed to reach truck height safely and efficiently. 
     2. Description of Related Art 
     Scissor-lift apparatus is known as evidenced by U.S. Pat. No. 3,220,698 to V. H. Carder. 
     Applicant has two patents, U.S. Pat. Nos. 5,275,526 and 5,333,340 relating to a wheeled elevator apparatus having characteristic similar to that of the present invention. The former patent relates to an elevator apparatus wherein the platform has two ramps for access to and from the platform and the access directions of these two ramps are perpendicular to each other. The latter patent is directed to an elevatable platform having (1) bumpers attached to it to absorb impacts by trucks; (2) a truck restraining hook to grasp the ICC bumper on the truck; and (3) ground anchor means to provide restraining forces to hold the elevatable platform in one location while preventing separation from the truck. 
     BRIEF SUMMARY OF THE INVENTION 
     This invention relates to a movable wheeled frame supporting a platform elevatable by hydraulic cylinder means; the frame includes screw-jacks which crank down to lift the frame off its rear wheels and provide a stationary load-bearing contact with the surface of a dock that is lower than the height of the truck; the platform being elevatable by the operation of pairs of arms connected to the frame and elevated by hydraulic cylinder means; the frame being adapted to rest on a level lower than the lowest level attainable by the platform. In some instances the frame base is more restricted in area than that of the elevatable platform. 
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
     The novel features believed to be characteristic of this invention are set forth with particularity in the appended claims. The invention itself, however, both as to its organization and method of operation, together with further objects and advantages thereof, may best be understood by reference to the following description taken in connection with the accompanying drawings, in which: 
     FIG. 1 is a side elevational view of one type of elevatable platform of this invention; 
     FIG. 2 is a top plan view of the elevatable platform of FIG. 1; and 
     FIG. 3 is a side elevational view of a second type of elevatable platform of this invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     This invention relates to a wheeled elevator apparatus for use in unloading or loading highway trucks carrying freight from place to place. Modern day transportation of freight over long distances normally begins and ends at a freight warehouse equipped with a dock, which is an elevated platform of wood, concrete, and/or steel, where a highway truck can back up to, open his cargo doors and wheel the freight from the truck onto the dock or into a warehouse for dry storage until it can be transferred to its intended destination. Because there are no rigid rules and regulations about the height or size of the dock, there are all sizes and shapes of docks; and furthermore, there are many heights and sizes and shapes of highway trucks that deliver freight to and from docks. Accordingly, there is a need to provide means for loading and unloading trucks of different heights and sizes onto and from docks of different heights and sizes. Generally freight is handled by hand trucks or powered trucks, such as fork-lift trucks, so as to use as little time as possible and as few humans as possible. In order to accomplish these purposes dock boards and dock levelers of many types have been used for many years to provide a bridge that is moderately adjustable in height to provide a smooth rolling surface to connect the dock with the inside floor of the truck. In many instances in the past such a smooth connector has not been available to adequately bridge the range of various truck heights for loading or unloading step-wise, e.g., (1) from the truck bed to the ground or dock and (2) from the ground to space available inside a warehouse, which might entail an intermediate step of lifting the freight up and onto a dock before moving it inside the warehouse for temporary storage. If the dock surface is sufficiently large to permit an elevator apparatus on the dock, such as those of applicant&#39;s previously mentioned patents, it might be relatively easy to unload the truck that could back up to that elevator apparatus positioned on the dock surface. If the dock was restricted in dock surface area, and the truck approach space is insufficient to position the elevator apparatus in front of the dock, the truck might have to be unloaded in the truck parking area and the freight separately and inefficiently transferred to the dock. It is an object of this invention to provide a wheeled elevator apparatus that can solve many of the freight transfer problems in instances where docks and trucks are ill-matched for freight transfer using previously available means by positioning a portion of the elevator on the dock surface and the remainder in front of the dock. 
     In FIGS. 1 and 2 there are shown two views of one type of elevator apparatus that can be rolled into position to provide a bridge between a low dock and a normally higher highway truck for the transfer of freight therebetween. In this situation a highway truck extends back to  30  with the truck floor  31 . The elevator apparatus having a frame  10  includes a truck-end ramp or bridge  14  and a dock-end ramp  13  connected to an elevatable platform ( 22  in A its elevated position and  23  in its lowered position). Freight on the truck is unloaded by moving it across ramp  14  to platform  12  in its elevated position  22 . Platform  12  is then lowered to position  23  where the freight is moved across ramp  13  to dock  25  which is level with the warehouse floor (not shown). The freight is normally moved by hand truck, pallet and hand pallet jack, electric powered pallet jack or truck (e.g., a fork lift motorized truck); or by any other means available. 
     The elevator apparatus includes a mainframe  10  having an upper elevated section  10 E and a lower chassis  10 C; and an elevatable position  22  or downward to its lower position  23 . The apparatus in these drawings includes two pairs of lifting arms  16 , a pair of hydraulic cylinders  15  suitable control levers  19 , and a railing structure  17  to keep persons and freight from falling off platform  12 . Arms  16  are shown at  16 E in their elevated position and  16 L in their lower position. Platform  12  has two access ramps that are in line with each other and are connected to platform  12  by hinges  29 , and may be folded upward when not in use or when the entire apparatus is moved to another location. Access ramp  13  connects platform  12  to dock  20  and ramp  14  connects platform  12  to the freight truck floor (shown only by  30  representing the rearmost wall of the enclosed truck. With both ramps  13  and  14  down in operating position as shown in FIGS. 1 and 2 there is a relatively flat and level surface from the interior of the truck to the warehouse floor for the movement of freight thereon. 
     Included are leveling and stabilizing jacks  18  attached to main frame  10  for lifting the apparatus off wheels  11  so as to provide a more steady and level elevator apparatus. There may be  2  or more jacks included on main frame  10 , although for illustration purposes there is shown only one in FIG.  1  and two in FIG.  2 . The apparatus, of course, has wheels transport  11  for moving it from place to place. The exact placement of wheels  11  is not a part of this invention since the art of wheel placement is well known and depends on the center of gravity of the apparatus. Shown in FIG. 1 is an arrangement for transporting the apparatus close to a dock having a lower than truck height upper surface. The design in FIG. 3 shows a different arrangement of supporting wheels when there is insufficient dock space to allow most of the lift to be placed on the dock. Of course, the arrangement of frame supporting wheels and jacks will depend on how much room there is on a given dock and in front of the dock, without taking up excessive truck approach space given the specific location. The weight of the lift and load on the lift is supported by both the jacks on the dock surface and the ground in front of the dock when the invention is positioned there for use. 
     Generally, there will always be included in this apparatus a bumper  24  which can absorb the shock of a truck backing too fast into the apparatus of this invention with the front surface of the dock furnishing the support to hold this invention in one spot when impacted. 
     FIG. 3 shows a different design for the elevator apparatus of this invention than that of FIGS. 1 and 2. Here the mainframe  10  of the apparatus has different designs for the upper elevator frame  10 E and the lower chassis frame  10 C than that of the apparatus shown in FIGS. 1 and 2. The frame in front of the dock is much longer in FIG. 3, which requires more parking and truck approach space in front of dock  20  and its facing  21  and bumper  27 . While requiring more space in front of the dock the apparatus requires less space on the dock. Less space on the dock surface means that the apparatus must function as a longer bridge beyond the dock than that of FIGS. 1 and 2. This may be an advantage in that the area of platform  12  may be made larger and therefore, the unloading or loading of the truck might be shorter in time than that when using a smaller platform as in FIGS. 1 and 2 which would not fit on top of the dock with limited space above. It is apparent that different designs of the apparatus may be appropriate for different docks, but each design will include the same features of wheels, ramps, and elevatable platform, and operating controls for platform movement and up and down hydraulically for load support and stabilization with a portion of this invention positioned in front of the dock and supported by the truck approach, and a portion positioned on the dock surface and supported by the dock. 
     While the invention has been described with respect to certain specific embodiments, it will be appreciated that many modifications and changes may be made by those skilled in the art without departing from the spirit of the invention. It is intended, therefore, by the appended claims to cover all such modifications and changes as fall within the true spirit and scope of the invention.