| 摘要 |
A shaft of a window actuator is operable to open and close a casement window sash when the shaft is rotated either by a hand crank or by a motor from inside of the premises. The shaft is automatically locked against rotation if a backdriving force is applied to the actuator from outside the premises. This prevents an open sash from being buffeted by wind and from being pulled open further by a potential intruder.
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