| 摘要 |
A release brake (1) for a window covering (4, 28) of the type having a roller (2) about which either a window covering material or lift cords (10, 12) are wound as a stationary member (20), a movable member in the shape of a drum (15), and a hub (17). In one embodiment particularly useful for a roller shade, the hub (17) is fixed and the surrounding movable member (15) can be restrained or released by a coil spring (23) encircling the hub (17). In another embodiment the member which surrounds the hub (17) is fixed and the hub (17) can be restrained or released by a coil spring (23) encircling the hub. The spring (23) is sized and positioned so that the spring (23) will press against the outside surface of the hub ( 17) when in a relaxed condition to restain the hub (17) or sized and positioned to press against the inside surface of the movable member when in a related condition to restain that member. The tangs (25, 27) of the spring (23) are moved relative to one another to increase the diameter of the spring (23) which releases the h ub (17) and allows it to rotate freely or to decrease the diameter of the spring (23) which releases the movable member (15) and allows it to rotate freely.
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