| 摘要 |
A fixed roller(2) and a moving roller(4), which is assembled with a spring(5), are attached on a base plate(1). One edge of a string(6) is fixed on the destination through a forward cramper (7), a moving roller, a fixed roller, a moving roller, and a backward crampr(8). Drawing of the string upward along the moving roller by the drawing force opens the lower cramper(7) and closes the backward cramper after attaching the load to the base plate. Release of the string closes the forward cramper and opens the backward cramper and it moves the base plate upward the same distance as the moving roller ascends. Drawing of the other string (9) opens the crampers and it descends the base plate.
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