| 摘要 |
The traction members of the blind are open chains (9). One, lower chain end is articulated on a connecting lever (8) which engages on the end rail (1a) of the blind. The other, upper chain end is guided over a chain wheel (7) resting on the drive shaft (3). When the blind is lowered, the chain (9) still extends by at least one chain link beyond the chain wheel (7). In this arrangement, the chain (9) is guided over its entire movement path with a small amount of play in a channel (11a, 11b, 11c) which prevents the chain from buckling out of said movement path. Between the end rail and chain wheel, the chains thus act as rigid bars. When the blind is lowered entirely or partially, it is not possible to push the blind up, because the drive shaft cannot be turned by the chain strand running thereon. <IMAGE>
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