| 摘要 |
The apparatus has an upper part with a U-shaped plate (1) fixed to the top of the door by a screw. This is joined to a support (2) for two pulleys (5,6) over which a cable (8) passes. A lower part slides under the door and is fixed to it by a U-shaped plate (21) and a screw (23). The plate is joined to a base (22) with a central shaft (20). A circular plate (25) with a central hollow tube (27) slides on the shaft and holds weights (28,29). The cable is fixed to the top of the tube by pin (24).
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