Patent Publication Number: US-2002003340-A1

Title: Load platform step construction

Description:
[0001] This invention relates to truck rear loading platforms, and more particularly, to steps for accessing personnel to the platform from ground level.  
       [0002] Many trucks have rear loading platforms adjacent to the rear loading doors. These platforms are relatively narrow. Typical steps which are relatively small are provided on the rear sides of the platform. These steps may be in the form of indentations in a rear platform side wall or rungs secured to the truck body frame at the rear. These steps are difficult to navigate especially during loading or unloading the vehicle. Because the platform is relatively narrow, there is insufficient room in the metes and bounds area of the platform to locate steps because the amount of area for loading purposes is limited.  
       [0003] U.S. Pat. No. 255,327 discloses a step for vehicles. This discloses a complex mechanism for displacing the step to an acquiescent stored position. However, this patent issued in 1882 and the disclosed structure is not readily adaptable for modern trucks. The quiescent stored position of the step would interfere with the loading platform region of a truck.  
       [0004] U.S. Pat. No. 578,332 shows a vehicle tail gate that also serves as a step. This structure is applicable to vehicles with tail gates and not to enclosed trucks with rear platforms.  
       [0005] U.S. Pat. No. 2,546,626 discloses a vestibule trap door arrangement in which a trap door is hinged to a platform and is locked in place with a brace to expose a stair well. The trap door when open to expose the stairs is upright and would interfere with the use of a truck rear platform during loading. This arrangement is for use with passenger rail cars.  
       [0006] U.S. Pat. No. 2,481,230 discloses a trailer having a deployed state and a collapsed state. In the deployed state a stair is shown that rotates into the collapsed state with the trailer. This stair when collapsed forms part of the collapsed trailer exterior contour not related to loading platforms of trucks. This disclosure does not disclose the above problem with rear loading truck platforms.  
       [0007] U.S. Pat. No. 5,868,412 discloses a stairway for flatbed vehicles. The stairway is in the bed of the vehicle and is covered by a lid that rotates from an open state to a closed state. In the open state the cover overlies the bed and stair. In a second embodiment, the truck rear door is aligned over the cover and stair. In either case, the open cover interferes with use of the truck bed during loading and unloading.  
       [0008] Still other stair arrangements for vehicles are disclosed in U.S. Pat. Nos. 3,580,613, 4,198,070, 5,505,476, 5,584,493, 5,695,207 and 5,816,638 and in French Patent 1.383.843. Some of these disclose stairs that are covered with a lid or the stair is retracted from a deployed position to a retracted position, and are not disclosed as useful with truck rear loading platforms  
       [0009] The present invention is a recognition of a need for a stable platform and step arrangement wherein the full use and integrity of the loading platform is available at all times. The loading platform includes a portion which has deployed and stored states such as to form an access stair to the loading platform that is relatively central the platform, convenient to use for loading and unloading cargo to and from the platform and yet does not interfere in any way with the use of the platform whether or not the step is in use in the deployed state.  
       [0010] A vehicle step construction for a cargo vehicle loading platform according to an aspect of the present invention comprises a vehicle loading platform defining a platform surface having an opening therethrough and arranged to be secured to the cargo vehicle and a stair structure having deployed and stored states aligned with the opening and rotatably secured to the platform, the stair structure including at least one step for accessing the platform through the opening in the deployed state and a platform member for rotation with and secured to the at least one stair so that the platform member encloses the opening in the stored state to form a continuation of and a portion of the platform surface.  
       [0011] In a further aspect, the stair construction comprises a frame pivotally secured to the platform aligned with the opening for rotation from and to the deployed and stored states, the at least one step being secured to the frame, and means for securing the platform member to the frame.  
       [0012] In a further aspect, the at least one step includes a first step secured to the platform member and a second step secured to the frame in spaced relation to the first step, the first and second steps for rotating with the frame.  
       [0013] Preferably a further step is fixedly secured to the loading platform in the opening and arranged to form a step arrangement with the at least one step.  
       [0014] In addition, the platform member preferably includes latch means secured thereto for releasably latching the stored stair structure to the platform.  
       [0015] In a further aspect, the latch means includes a movable handle including means for recessing the handle in the platform surface and a latch responsive to the displacement of the handle for releasing the latched stair structure.  
       [0016] In a further aspect, the frame comprises first and second spaced gusset members and pivot means for pivotally securing the gusset members to the loading platform, the at least one step being secured to and extending to and between the gusset members.  
       [0017] Preferably, the gusset members are flat steel plates, and the at least one step is stamped sheet metal.  
       [0018] In a further aspect, the latch means are coupled to the stair structure and platform for releasably latching the stair structure in the stored state. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWING  
     [0019]FIG. 1 is a perspective view of a truck vehicle rear loading platform with a deployed step arrangement according to the present invention;  
     [0020]FIG. 2 is a side elevation sectional view of the rotating frame and step configuration of the embodiment of FIG. 1;  
     [0021]FIG. 3 is a front elevation view of the embodiment of FIG. 1;  
     [0022]FIG. 4 is a perspective view of the platform of FIG. 1 with the step arrangement in the stored state; and  
     [0023]FIG. 5 is an isometric view of the handle portion of the latch device of the structure of FIG. 1. 
    
    
     [0024] In FIGS. 1, 3 and  4 , stair assembly  2  comprises by way of example a truck rear loading platform  4  and stair construction  6 . The platform  4  includes a platform structure  8  formed of stamped sheet steel having a platform loading surface  10 . The platform  4  extends rearwardly from a cargo receiving chamber formed by truck body  12 , FIG. 4. The remainder of the truck is not shown. The platform  4  may be connected as the floor bed of a body  12  fixed to a truck cab or part of a truck trailer bed. While the platform  4  is by way of example described as a rear platform, its orientation with respect to the truck body  12  may be varied to a side of the body as desired. Also, the platform  4  may be part of a flat bed truck body either fixed to a cab or associated with a flat bed trailer. While the platform  4  is also illustrated as use with a vehicle, such a platform may be implemented in non-vehicular environments. The platform  4  may have a roughened surface  10  formed with an array of projections  14  to minimize slipping as known in this art.  
     [0025] Two spaced flanges  15  and  17  depend from the outer rear peripheral edges of the platform structure  8  and may be formed one piece and integral with the surface portion of the structure  8  which may have other flanges also formed one piece therewith. A forward flange  19 , FIG. 1, formed one piece with the structure  8 , depends from the forward edge of the surface  10  and is attached to the truck frame by elements such as beams and welds or bolts (not shown). Platform support beams (not shown) for supporting the surface  10  portion of the platform structure  8  may also be used according to a given implementation. The term forward as used herein refers to the front of the associated vehicle and the term rear refers to the rear of the vehicle.  
     [0026] Two steel beam posts  16  and  18  depend from and are secured to the platform structure  8 , e.g., preferably welding, in spaced relation. The posts  16  and  18  are hollow and may be square or rectangular in cross section. The platform structure  8  has a through opening  20  therein. The opening  20  extends from rear edge  22  forward to the truck cargo body  12 , FIG. 4. The opening  20  has a width w sufficient and a length in the rear-forward direction to form a stair well  21  for a person, for example,  2 - 3  feet in width w. The platform  4  has a rear-forward length of about 2-4 feet. A steel plate  24  is secured to post  16  and a steel plate  26  is secured to post  18  in the opening  20  forming the width of the well  21 . Plates  24  and  26  are preferably rectangular and depend from the platform structure  8  for the length of the posts  16  and  18 . The plates may be welded to the platform structure  8  and to the posts and other structure (not shown). The plates  24  and  26  form the interior of stair well  21  aligned with the opening  20  at the top of the stair well. The platform structure  8  has a depending flange  28  in the opening  20  at the forward edge of the opening  20 . This flange  28  and its associated platform surface may be aligned beneath the closed cargo rear doors  12 ′ and  12 ″, FIG. 4, and therefore is not seen in this figure. In the alternative, the doors may be further forward with a portion of the platform  4  adjacent to the opening  20  extending rearward of the doors to the opening  20 .  
     [0027] A one piece steel plate U-shaped step  30  is attached to and between the plates  24  and  26  either by bolts (not shown) or welds. The step  30  is placed vertically below the plane of the platform surface  10  a distance at a conventional stair riser spacing.  
     [0028] Stair construction  6  includes stair subassembly  32 . The subassembly  32  includes two side gusset members  34  and  36 . In FIG. 2, representative gusset member  34  comprises a steel plate including an upper section  38  and a lower section  40 . Upper section  38  has a semi-circular edge  42  and a rectangular portion  44 . The lower section  40  has a rear edge  46  that is inclined toward the adjacent edge  48  of the upper section. The upper and lower sections have a coextensive front edge  50 . A bearing through opening  52  is formed in the upper section  38 . The gusset member  36  is identical to the member  34  thus far described. A latch opening  54  is also formed in the member  34  only.  
     [0029] A U-shaped one pieced stamp sheet steel step  56  is welded at its ends to and between the gusset members  34  and  36 . A formed platform member  58  is welded to and between the gusset members  34  and  36 . The platform member  58  has a surface  60  that is formed with projections the same as on the surface  10  of the platform structure  8 . In FIG. 2, the member  58  has a flange  62  at the edge  46  of the gusset member  34  (and  36 ) and a flange  64  at the opposite edge. The flange  62  is at the rear and the flange  64  is at the front of the stair well  21  in the deployed state of the subassembly  32 , FIGS. 1 and 3. In the stored state of the subassembly  32 , FIG. 4, the surface  60  is coextensive with the platform surface  10  and forms a continuation and portion of the platform surface in the opening  20 . The opening  20  is substantially covered and the well  21  is enclosed by the platform member  58 .  
     [0030] In FIG. 2, a shaped one piece formed steel plate forms step  66  and is welded to the flange  62  and to and between the gusset members  34  and  36 . The step  66  has forward and rear flanges  68  and  70 , respectively (in the orientation of FIG. 2) and lips that bend inwardly from these flanges and abut the platform member  58 . Step  66  forms the lowermost step of the subassembly  32  in the deployed state of FIGS. 1 and 3. The opening  54 , FIG. 2, is in communication with the chamber  55  formed by step  66 , platform  58  and the gusset members.  
     [0031] The gusset members  36  and  38 , FIGS. 1 and 3, are respectively pivotally attached to the corresponding stair well  21  plates  24  and  26  at bearing openings  52  by bolt-bushing and nut assemblies  72 . Other bearing arrangements may be provided in the alternative for pivotally securing the stair subassembly  32  to the plates  24  and  26  and thus to the platform structure  8 .  
     [0032] In FIG. 5, the platform member  58  is formed with an opening  74 . A latch mechanism  76  is secured to the member  58  in the chamber  55  (FIG. 2). The mechanism  76  includes a loop handle  78  which is pivotally secured so it may extend upright as in FIG. 5 or folded over flat so it is recessed beneath the surface  60  of the platform member  58 , FIG. 4. A latch  80 , which is an elongated rod attached to mechanism  76  and operated thereby, passes through the opening  54 , FIG. 2. Rotation of the handle  78  in directions  81 . FIG. 5, reciprocates the latch  80  in directions  82 . A latch receptacle (not shown) is in plate  24  at the top of the well  21  adjacent to the opening  20  receives the latch  80  as in conventional door latches which is resiliently secured for displacement in directions  82 . The latch  80  normally engages the receptacle when the subassembly is rotated to the stored retracted state of FIG. 4. This latch engagement secures the subassembly in this position.  
     [0033] In operation, in FIG. 4, the handle of the latch mechanism  76  of the stored subassembly  32  forming the stair structure is lifted to the position of FIG. 5 and rotated to release the latch  80  (FIG. 3). The subassembly  32  is then manually grasped and rotated about the journal-bearing formed by the assembly  72 . The subassembly is fully rotated to the position of FIGS. 1 and 3. In this deployed state, the platform member  58  is beneath the stair subassembly  32  and the steps  30  (fixed),  56  and  66  (rotatable) are aligned in the stair well  21  to provide easy access to the platform  4  without obstruction on the platform by any of the elements of the subassembly  32 . A person may load the truck via the steps with ease and safely due to the wide access of the stairs to the platform.  
     [0034] When the stair is not in use, it is rotated to the retracted stored state of FIG. 4 where it automatically latches in position when placed in its full stored position. The platform member  58  surface  60  is now coplanar with the surface  10  of the remainder of the platform  4  to form a safe continuous load platform for a person without obstruction and with sufficient strength to support a person and any load carried by the person. Prior art stairs with rotating lids interfere with the use of such a platform and are not desirable for this implementation.  
     [0035] It will occur to those of ordinary skill that various modifications may be made to the disclosed embodiments. The scope of the invention is intended to be defined by the appended claims.