| 摘要 |
A winding mechanism for controlling the retraction and deployment of an architectural covering, such as a window blind or shade having a winding element 12, about which the covering, or its lift cord or tapes are wound and unwound with rotation of the winding element about a first axis of rotation, and a fluid brake 40 for retarding the rotation of the winding element in at least one direction about the first vaxis. The fluid brake comprises a fluid tight compartment 42 containing a liquid and an impeller 46. The compartment and the impeller are adapted for relative rotation about a second axis, which can be the same as or coaxial with the first axis. Either the compartment or the impeller is operatively connected to the winding element. In operation the liquid rotates with the rotation of the compartment or the impeller about the second axis. Rotation of the liquid relative to the impeller or to the compartment in at least a first direction about the second axis is effective to retard the rotation of the winding element in at least a second direction about the first axis. The impeller 46, or a peripheral wall surface 43 of the compartment 42 has a first surface 49B that extends generally radially and substantially parallel with respect to the second axis.
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