| 摘要 |
The moving shutter to cover an aperture comprises a curtain (1) of articulated panels which slide in a guide (2) to close or open. A cable (3) is attached to the last shutter panel (16) and passes successively over pulleys attached to a jack and piston (7,6). Three of these pulleys (5,51,52) are fixed (4,10) adjacent to the last shutter panel (16) as is the end of the jack piston (7) and three further pulleys (81,82,83) are attached to an axis fixed to the free end of the jack (71). When the shutters are opened, the air jack is compressed with a considerable mechanical advantage. The stored energy is used later to reclose the shutters after their release.
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