to direction b as cable 38 brings frame 10 to its balance point over pivots 14 as seen in fig2 that is when the center of gravity of frame 10 is approximately vertically over pivots 14 frame 10 no longer has to be hoisted by cable 38 but rather is thereafter lowered by cable 38 under its own weight thus after frame 10 pivots to an over center position either while being deployed or stowed hoisting by cable 38 in direction b 39 is replaced by lowering of frame 10 by cable 38 in direction b as seen in fig1 14 curved supporting brackets 52 may be employed to support an elongate tarp hold down such as pipe 54 a flexible roof cover such as tarp 56 is mounted along its opposed edges to a pair of pipes 54 the weight of pipes 54 may be used to tension the tarp to form a roof covering over frame 10 specifically over removable rigid roof span members 57 where span members 57 rest on upper members 10c and be releasably secured thereon such tensioning of the tarp may also be accomplished by rolling tarp 56 onto pipes 54 such rolling also facilitates storage of tarp 56 brackets 52 may be clipped into the open uppermost ends of vertical members 10d by means of clips 58 on brackets 52 u shaped channel clips 60 seen in fig1 may be used to fasten flexible coverings such as further tarps to.