Abstract:
The present invention is a loading ramp assembly for loading objects onto a floor of a vehicle. The loading ramp assembly includes a multi-sectioned, foldable ramp capable of being stored in a compact enclosure located under the vehicle floor. The loading ramp assembly also includes a telescopic ramp supporting frame that alone slidably supports and retracts the ramp between an unfolded loading position, inclined from the rear of the vehicle floor to the ground, and a folded storage position within the compact underbody enclosure.

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to a ramp assembly for loading objects onto a floor of a vehicle, and more particularly to a foldable retractable loading ramp stowable within a compact underbody enclosure. 
     BACKGROUND OF THE INVENTION 
     Loading ramp assemblies which are stowable beneath the floor of a vehicle are known. In many of these assemblies, the ramp is withdrawn from the rear of the truck, pivoted about a supporting frame, and attached to the rear of the cargo floor to provide an incline to the ground for the loading and unloading of objects from the vehicle. 
     Vehicle operators naturally prefer longer ramps to shorter ramps, as the longer ramps provide a more gradual incline to the ground. Providing cargo vehicles with longer ramps, and storing these ramps under the vehicle body, has been difficult and sometimes impossible. Short body trucks have been limited to a short ramp because of the limited space under the cargo area. However, even with large body cargo vehicles, providing the storage space for a long ramp below the cargo floor requires an expensive revision to the vehicle frame and differential, as well as the relocation of certain vehicle components such as the fuel tank. 
     The present invention solves these problems by providing a retractable ramp assembly with a foldable ramp, allowing for the storage of a long ramp in a confined area. Multiple ramp sections are folded and retracted into a compact underbody enclosure. The small size of the enclosure requires no revisions to the vehicle frame or differential, and does not interfere with underbody components. When removed and unfolded the ramp is long, providing a gradual incline to the ground for object loading and unloading. 
     In addition to the underbody limitations affecting the length of presently known ramp assemblies, maximizing the width of a loading ramp has also been a problem. Positioning a loading ramp assembly between the longitudinal framing members below the cargo floor limits ramp width. Presently, loading ramp assemblies include a ramp, a ramp supporting frame and a mechanism to slide the ramp and supporting frame out from under the cargo floor. These three components combine to severely limit the overall width of the ramp alone. 
     The present invention also solves this problem by providing a telescopic ramp supporting frame that alone slidably supports the ramp between a storage position within a compact underbody enclosure and a loading position providing a gradual incline from the rear of the cargo floor. Eliminating a separate sliding mechanism provides additional space between the longitudinal underbody framing members for a wider loading ramp. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to a retractable loading ramp assembly having a foldable ramp, allowing for the storage of a long ramp within a compact underbody enclosure. This invention is also directed to a retractable loading ramp assembly having a telescopic ramp supporting frame that alone slidably supports the ramp between a storage position within a compact underbody enclosure and an inclined loading position from the rear of the cargo floor to the ground. The telescopic ramp supporting frame eliminates the need for a separate sliding mechanism, in addition to the ramp supporting frame, allowing for a wider loading ramp. 
     In one embodiment of the present invention, a telescopic ramp supporting frame is mounted below a floor of a vehicle. A ramp is connected to the frame and the frame slidably positions the ramp between the loading and storage positions. The ramp assembly may also include an enclosure mounted below the floor and the frame would be mounted within the interior of the enclosure. The frame may include two, three, four or more telescopic sections, where the telescopic sections provide the slidability for positioning the ramp between the loading and storage positions. The telescoping sections may include internal slide guides to maintain the alignment of the frame. The ramp may include two, three, four, or more foldable sections. The sections would be folded when the ramp is in the storage position and unfolded when the ramp is in the loading position. The ramp may include a sill plate, providing a smooth transition between the ramp and the floor of the cargo vehicle when the ramp is in the loading position. The sill plate may include a door latch access hole providing for the latching and securing of an overhead door when the ramp is in the loading position. 
     In a second embodiment of the present invention, the ramp assembly includes an enclosure mounted below the cargo floor of a vehicle, a slidable mechanism connected to the interior of the enclosure, a ramp supporting frame connected to the slidable mechanism, and a foldable ramp. The ramp may include two, three, four, or more foldable sections. The ramp is attached to the frame and the slidable mechanism positions the ramp and the frame between a loading position and a storage position. In the storage position, the ramp is folded and retracted into the enclosure. In the loading position, the ramp is removed from the enclosure, unfolded and inclined with one end on the ground and the other end attached to the rear of the cargo floor. The end of the ramp attached to the cargo floor includes a sill plate providing a smooth transition between the ramp and the floor of the vehicle. The sill plate includes a door latch access hole providing for the latching and securing of an overhead door while the ramp is in the loading position. 
     In a third embodiment of the invention, the ramp assembly includes an enclosure mounted below the floor, a telescopic ramp supporting frame connected to the interior of the enclosure, and a foldable ramp. The ramp may include two, three, four, or more foldable sections. The ramp is attached to the frame and the frame telescopically positions the ramp between the loading and storage positions. The ramp supporting frame may include two, three, four, or more telescoping sections. The end of the ramp connected to the rear of the cargo floor may include a sill plate, which may include a door latch access hole. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For the purpose of illustrating the invention, there is shown in the drawings a form which is presently preferred; it being understood, however, that this invention is not limited to the precise arrangements and instrumentalities shown. 
     FIG. 1 illustrates a plan view of a foldable retractable ramp assembly according to one embodiment of the present invention; 
     FIG. 2 illustrates an elevation view of a foldable retractable ramp assembly according to another embodiment of the present invention; 
     FIG. 3 illustrates a plan view of a ramp supporting frame with a slidable mechanism, included as part of the ramp assembly shown in FIG. 2; 
     FIG. 4 illustrates an elevation view of the ramp supporting frame of FIG. 3; 
     FIG. 5 illustrates a plan view of a telescopic ramp supporting frame having two sections, included as part of a foldable retractable ramp assembly according to further embodiment of the present invention; 
     FIG. 6 illustrates an elevation view of the telescopic ramp supporting frame of FIG. 5; 
     FIG. 7 illustrates an elevation view of an unfolded and extended three-section ramp according to another embodiment of the present invention; 
     FIG. 8 illustrates an elevation view of the folding of the three-section ramp of FIG. 7; 
     FIG. 9 illustrates an elevation view of the completely folded three-section ramp of FIG. 7; 
     FIG. 10 illustrates a plan view of a truck-end ramp section having a sill plate according to further embodiment of the present invention; 
     FIG. 11 illustrates an elevation view of the truck-end ramp section of FIG. 10; 
     FIG. 12 illustrates a plan view of a truck-end ramp section having a slide-bolt assembly according to a still further embodiment of the present invention; and 
     FIG. 13 illustrates an elevation view of the truck-end ramp section of FIG.  12 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to the drawings, wherein like numerals indicate alike elements, there is shown in FIG. 1 an illustration of a plan view of a foldable retractable loading ramp assembly  10 . The loading ramp assembly  10  includes a ramp  12  having three sections and a three-part telescopic ramp supporting frame  13  connected to a truck  16 . The telescopic ramp supporting frame  13  telescopically positions the ramp  12  between a storage position and a loading position. Variations of the embodiment of FIG. 1 could include a two, four or more section ramp, or a two, four or more section telescopic ramp supporting frame. 
     FIG. 2 is an elevation view of a foldable retractable loading ramp assembly  10  having a three-section ramp  12 , a ramp supporting frame  14 , and an enclosure  18  mounted below the cargo floor  17  of a truck  16 . The ramp supporting frame  14  (not telescopic) is connected to a sliding mechanism (not shown) which provides the slidable positioning of the frame  14  and the ramp  12  between a stowable position within the enclosure  18  and a loading position as shown in FIG.  2 . In the loading position, the ramp  12  is unfolded and extended on an incline from the rear of the cargo floor  17  to the ground. At the top of the ramp  12  a sill plate  41  provides a smooth transition between the ramp  12  and the cargo floor  17 . Variations of the embodiment of FIG. 2 could include a two, four or more section ramp, or a multi-sectioned telescopic ramp supporting frame. 
     FIG. 3 is a plan view and FIG. 4 is an elevation view of the ramp supporting frame  14 . FIG. 3 also illustrates a slidable mechanism  26 , such as a drawer slide type device, which slidably positions the frame  14  and the ramp  12  between the storage and loading positions. The ramp supporting frame  14  includes two parallel supporting members  20  connected by a cross-member  22 . Each supporting member  20  includes one bumper mount  24  which supports the ramp assembly on a bumper of the truck  16  when the ramp  12  is in the loading position (as shown in FIG.  2 ). An attachment hole  29  is located at the ramp  12  end of each supporting member  20 , for pivotal connection with the ramp  12 . 
     The slide mechanism  26  includes an outer slide section  26   a , a middle slide section  26   b  and an inner slide section  26   c . The sections  26   a ,  26   b  and  26   c  slidably interlock to position the ramp  12  between the loading and storage positions. The inner slide section  26   c  is connected to a respective supporting member  20 . The outer slide sections  26   a  are connected to the interior of the enclosure  18  or to an underbody framing member of the truck  16  if no enclosure  18  is present. 
     FIG. 5 is a plan view and FIG. 6 is an elevation view of a two-part telescopic ramp supporting frame  15 . The two-part telescopic frame  15  includes two parallel outer support members  32  and two parallel inner support members  30 . The two inner support members  30  and the two outer support members  32  communicate telescopically, with the inner support member  30  fitting within the outer support member  32 . The outer support members  32  are connected and braced to each other by a fixed cross member  34 . The inner support members  30  are connected and braced to each other by an alignment cross member  36 . Internal slide guides  38  may exist within each of the outer support members  32  to facilitate the telescopically sliding communication between the inner support members  30  and the outer support members  32 . 
     The two-part telescopic ramp supporting frame  15  could be implemented in the loading ramp assembly  10  of FIGS. 1 or  2 , replacing the three-part telescopic ramp supporting frame  13  shown in FIG. 1 or the ramp supporting frame  14  shown in FIG.  2 . 
     FIGS. 7,  8  and  9  illustrate the three-section ramp  12  in various foldable positions. FIG. 7 shows the ramp  12  in an unfolded, loading position. The three-section ramp  12  includes a truck-end ramp section  12   a , a middle ramp section  12   b , and a ground ramp section  12   c . At one end of the truck-end ramp section  12   a , a sill plate  41  exists for attachment to the cargo floor  17  of the truck  16 . Connecting each of the three ramp sections  12   a ,  12   b , and  12   c , a hinge  40  exists to facilitate the folding of the ramp  12 . 
     FIG. 8 illustrates the three-section ramp  12  being folded from an extended loading position (FIG. 7) to a folded, storage position (FIG.  9 ). The arrows of FIG. 8 demonstrate the direction in which the middle ramp section  12   b  and the ground ramp section  12   c  are hinged and folded in relation to the truck-end ramp section  12   a  to attain the completely folded ramp position of FIG.  9 . FIG. 9 illustrates the three-section ramp  12  in its folded storage position. It is in this folded position that the ramp  12  is retracted for storage, while supported on one of the three described ramp supporting frames ( 13 ,  14 , or  15 ), into the enclosure  18  under the cargo floor  17  of the truck  16 . 
     FIG. 10 is a plan view and FIG. 11 is an elevation view of the truck-end ramp section  12   a . The truck-end ramp section  12   a  includes a sill plate  41  with a door latch access hole  43 . In the ramp  12  loading position, the sill plate  41  extends from the truck-end ramp section  12   a  into a contoured sill  19  of the cargo floor  17 , providing a smooth transition between the ramp  12  and the cargo floor  17 . The door latch access hole  43  allows the truck operator to close and secure an overhead cargo door of the truck  16  while the ramp  12  is in the loading position. 
     FIG. 12 is a plan view and FIG. 13 is an elevation view of an alternative embodiment of the truck-end ramp section  12   a . The truck-end ramp section  12   a  includes two slide bolt assemblies  45 . In the loading position, the bolt of each slide bolt assembly  45  aligns with a hole in the sill  19  of the cargo floor  17  to secure the ramp  12  to the cargo floor  17 . 
     These and other advantages of the present invention will be apparent to those skilled in the art from the foregoing specification. Accordingly, it will be recognized by those skilled in the art that changes or modifications may be made to the above-described embodiments without departing from the broad inventive concepts of the invention. It should therefore be understood that this invention is not limited to the particular embodiments described herein, but is intended to include all changes and modifications that are within the scope and spirit of the invention as set forth in the claims.