| 摘要 |
Several frames are combined to form a compact unit (HE2) when they are all retracted, each frame comprising a top frame section, a bottom frame section, and vertical struts extending between the corners of the top and bottom frame sections. Except for the top frame, which has the smallest surface area, all of the frames are provided with top and bottom pulleys (5, 6) in the corners of the top and bottom frame sections respectively. The bottom frame sits on top of a base plate (12) and has a winch rotatably mounted on top of it for a pulley cable (9) extending alternately over the top and bottom pulleys in each frame, before ending at an anchor point in the bottom frame section of the top frame. Winding the cable around the winch will cause the frames to be raised until they hit a stop. Conversely, unwinding the cable from the winch will return the frames to their retracted state.
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