angle 94 lower angle 96 side angles 98 and vertical reinforcement 100 upper angle 94 is secured to side panel plate 92 at upper edge 102 lower angle 96 is secured to lower edge 104 of side panel plate 92 side angles 98 are secured to side edges 106 of side panel plate 92 these structures may all be secured for example by welding vertical reinforcements 100 extend generally vertically between upper angle 94 and lower angle 96 upper angle 94 further includes central secondary support tab 108 pierced by fastener hole 110 lower angle 96 also includes corner tabs 112 pierced by fastener hole 114 and central primary support tab 116 pierced by fastener hole 118 side edges 106 also include hinge barrels 120 secured to an outer portion thereof hinge barrels 120 are sized and structured to receive hinge barrels pins 122 therethrough hinge barrel pins 122 are structured to accept r clip 124 at an end thereof referring particularly to fig1 primary support beams 32 generally include inner end 126 outer end 128 and central portion 130 inner end 126 is pierced by gusset fastener holes 132 outer end 128 is pierced by lower panel fastener holes 134 central portion 130 is pierced by central beam fastener holes 136 secondary support beams 34 generally include inner end 138 and outer end 140 inner end 138 is pierced by primary support fastener holes 142 outer end 140 is pierced by panel fastener holes 144 primary support beams 32 and secondary support beams 34 may be fabricated from steel angle or.