Abstract:
A cargo bed has a succession of swinging side wall panels whose top margins self-align when staked in upright positions.

Description:
TECHNICAL FIELD 
     The disclosed subject matter relates to a cargo bed onto which cargo is loaded for transport, commonly on a truck vehicle. 
     BACKGROUND 
     Some cargo beds which have a succession of side wall panels which can be individually swung selectively to upright positions that place top margins of the side wall panels higher than the floor, and downwardly from upright positions to non-upright positions. In order to keep the top margins of successive side wall panels aligned with each other, a side wall panel may be latched to an adjacent one by a releasable latch mechanism at their top margins. 
     SUMMARY 
     The present disclosure provides mechanisms for self-aligning top margins of successive side wall panels without latches. 
     One general aspect of the disclosed subject matter relates to a cargo bed comprising a multi-sided floor for providing underlying support for cargo and at least one side wall panel mounted for swinging about an axis which passes through a bottom margin of the side wall panel parallel with a side of the floor for enabling the side wall panel to be swung selectively to an upright position which places a top margin of the side wall panel higher than the floor and downwardly from upright position to a non-upright position. 
     The cargo bed further comprises an upwardly open channel which has a length parallel with the side of the floor and through which the axis passes. At least one stake is selectively positionable on the side wall panel to stake and unstake the side wall panel to and from the upwardly open channel, and at least one spring mechanism is disposed to apply force to the bottom margin of the side wall at a location above the axis which opposes swinging of the side wall panel to the upright position and which when the side wall panel has been swung to upright position, applies force which keeps the bottom margin of the side wall panel fast against a wall of the channel. 
     Another general aspect relates to a truck vehicle for transporting cargo and comprising a cargo bed having a multi-sided floor for providing underlying support for cargo and multiple side wall panels mounted in succession along a side of the floor for swinging about a common axis which passes through bottom margins of the side wall panels parallel with the side of the floor for enabling each side wall panel to be individually swung selectively to an upright position which places a top margin of the side wall panel higher than the floor in lengthwise alignment with the top margin of a succeeding side wall panel, and downwardly from upright position to a non-upright position. 
     The cargo bed further comprises a succession of aligned upwardly open channels which extend lengthwise parallel with the side of the floor and through which the axis passes. 
     At least one stake is selectively positionable on each side wall panel to stake and unstake the side wall panel to and from a respective upwardly open channel, and at least one spring mechanism is disposed to apply force to the bottom margin of each side wall at a location above the axis which opposes swinging of a side wall panel to the upright position and which when a side wall panel has been swung to upright position, applies force which keeps the bottom margin of the side wall panel fast against a wall of the respective upwardly open channel 
     The foregoing summary is accompanied by further detail of the disclosure presented in the Detailed Description below with reference to the following drawings which are part of the disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a left side view of a truck vehicle which has a cargo bed. 
         FIG. 2  is a fragmentary perspective view of a portion of the cargo bed. 
         FIG. 3  is an enlarged fragmentary perspective view with a portion broken away to show more detail. 
         FIG. 4  is a fragmentary plan view in cross section of a spring mechanism. 
         FIG. 5  is an enlarged fragmentary perspective view with a portion broken away to show more detail. 
         FIG. 6  is another enlarged fragmentary perspective view with a portion broken away to show more detail. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows a truck vehicle  10  having a chassis  12 , including a chassis frame  14  on which a cab body  16  is supported. A hood  18  in front of cab body  16  covers an engine which is part of a powertrain which propels truck vehicle  10  via rear drive wheels  20 . Truck vehicle  10  is steered via front steered wheels  22 . 
     To the rear of cab body  16  chassis frame  14  supports a cargo bed  24  which, as shown in  FIG. 2 , comprises a horizontal floor  26 , a right side wall  28 , and a left side wall  30 . Cargo bed  24  may also comprise a front wall immediately to the rear of cab body  16  and an opposite rear wall. Each of the two side walls  28 ,  30  comprises multiple side wall panels  34  which can be swung from an upright position outwardly and downwardly as suggested by arrows  36  in  FIG. 2  which show one side wall panel  34  swung in excess of 90° from upright position. 
     Each side wall panel  34  comprises multiple posts  38  (see  FIG. 3  also) to which sheeting  40  is attached. Rigid rectangular steel tubing is a suitable material for posts  38 , and posts  38  may occasionally be referred to as tubes  38  in the following description. Stamped sheet steel is a suitable material for sheeting  40 , allowing it to be joined to posts  38  by welding. A side wall panel may also comprise additional structural members such as horizontal rails  42 . 
       FIG. 3  shows a side wall panel  34  which comprises four rectangular steel tubes  38 . Two of tubes  38  are outer end posts and the other two are inner intermediate posts. A respective stake  44  is associated with each intermediate post  38 . Each stake  44  is movable along the length of the respective post  38  for staking side wall panel  34  to cargo bed  24  when the side wall panel is in upright position and for unstaking the side wall panel from the cargo bed to allow the side wall panel to be swung outwardly and downwardly from upright position and thereafter swung back to upright position. 
     Each side wall panel  34  can swing about a common horizontal axis  46 . A bottom end of each outer end post  38  extends beyond a bottom margin of the respective side wall panel&#39;s sheeting  40  and contains a hinge barrel  48  which is exposed in  FIG. 5  by the outer end post from the nearer side wall panel having been removed for the purpose of illustration. In this way, confronting ends of adjacent side wall panels have aligned hinge barrels  48  through which a pivot pin  50  extends to enable each side wall panel to swing about axis  46  independently of adjacent side wall panels. 
     Each stake  44  comprises a proximal end which contains a round bar  52  extending transversely from opposite sides through respective slots  54  in opposite walls of the respective tube  38 . A stake is moved by applying force to its bar  52  in either a proximal or a distal direction. Slots  54  extend lengthwise of each post  38  to guide movement of stake  44  within a range of travel between an extended position shown in  FIG. 3  where bars  52  are at or near one limit of the travel range. Applying a proximal force to a bar will move it from the illustrated extended position to a retracted position at or near an opposite limit of the travel range. Manual access to stakes  44  for staking and unstaking a side wall panel  34  is available on the floor side of the cargo bed. 
     Running lengthwise along right and left sides of cargo bed  24  are upwardly open channels  60  each having a horizontal bottom wall  62 , a vertical inner side wall  64 , and a vertical outer side wall  66 . Each channel  60  is substantially coextensive in length with a respective side wall panel  34  but is free of interference with the swing of the side wall panel about axis  46 . With a side wall panel in upright position and its stakes  44  in extended position, a distal end portion of each stake is disposed within the respective channel as shown in  FIG. 6 . 
     That distal end portion comprises a succession of wedging surfaces  68  which are joined by supporting surfaces  72  on which a wedge  70  can be supported. Wedge  70  has supported surfaces  74  via which it can rest on supporting surfaces  72  when the stake is in retracted position. Wedge  70  also comprises a succession of wedged surfaces  76  each of which is joined with an adjacent wedged surface  76  by a supported surface  74 . 
     With side wall panel  38  upright and a stake  44  in retracted position, both stake  44  and wedge  70  are clear of channel  60  with the force of gravity causing wedge  70  to rest on the distal end portion of stake  44 . As a stake  44  is moved toward extended position, the weight of wedge  70  keeps it supported on stake  44  as both stake and wedge enter channel  60 . 
     The distance between a flat outer surface  80  of stake  44  and a flat inner surface  82  of wedge  70  is less than the distance between channel side walls  64  and  66 , enabling the stake and wedge to enter channel  60 . Wedge  70  extends slightly beyond the distal end of stake  44  and will come into abutment with bottom wall  62  which arrests its movement. Continued movement of stake  44  then begins to force stake and wedge apart until surfaces  80  and  82  are forced against walls  66  and  64  respectively, thereby wedging the stake and wedge in the channel and consequently preventing side wall panel  34  from being swung from its upright position. 
     After stake  44  has moved sufficiently toward retracted position to remove both stake and wedge out of channel  60 , side wall panel  34  can be swung down from its upright position. That unwedging of a stake results in wedge  70  being carried by stake  44  out of channel  60 . The size of tube  38  allows some free movement of the stake and wedge within the interior of the tube while preventing wedge  70  from coming off stake  44 . 
     Additional forces are being applied to a side wall panel  34  as its stakes  44  are being wedged in channel  60 . Those forces are provided by two compression spring mechanisms  90  mounted on cargo bed  24  near the lengthwise ends of the side wall panel. The locations are marked in  FIGS. 2 and 3  by the reference numerals  90 . 
       FIG. 4  shows an example of such a spring mechanism. A plunger  92  is mounted on a wall of cargo bed  24  for horizontal displacement in a direction transverse to the length of a side wall panel  34  and is biased in an outward direction by a helical compression spring  94 . Spring mechanism  90  assumes the condition shown in  FIG. 6  when side wall panel  34  has been unstaked and swung out of upright position far enough to lose contact with a head  96  of plunger  92 . 
     As side wall panel  34  is swung back toward upright position, outer end posts  38  will abut heads  96  of plungers  92  before the side wall panel reaches upright position. As the side wall panel continues toward upright position, springs  94  are increasingly compressed, urging the bottom margin of the side wall panel which is within channel  60  outwardly against channel side wall  66  with ever increasing force. By forcing the bottom margin of side wall panel  34  against side wall  66  with large forces, 500 pounds each for example, at locations just above axis  46 , the side wall panel is held secure. The location of each spring mechanism just above axis  46  provides a sufficiently long lever arm to overcome the large spring forces for enabling a person pushing on the top margin of a side wall panel to force the side wall panel to upright position where it can be staked to cargo bed  24 . 
     The coactions of the spring forces applied by spring mechanisms  90  and the wedging forces applied by stakes  44  and wedges  70  collectively cause a side wall panel  34  to be held secure in a geometrically defined position in relation to its channel  60 . A combination of precise dimensional alignment of all channels  60  along each side of cargo bed  24  and of structural rigidity of each side wall panel  34  and channel  60  results in the upper margins of successive side wall panels  34  attaining proper alignment with each other along each side wall  28 ,  30  without a latch mechanism for latching the upper margin of each side wall panel to an adjacent one.