| 摘要 |
A power actuator for a window includes a rotary drive member and a rotary driven member which is turned by the drive member and which is connected to the sash of a window to open and close the sash as the drive member is turned in one direction or the other. A reversible electric motor drives a speed reducing gear train and the output gear of the train is coaxial with and rotatable relative to the drive member, a crank arm with a projecting pin is pivotally mounted on the drive member to swing between an active or radially projecting position and an inactive position overlying the drive member. When the arm is in the inactive position, the pin connects the output gear and the drive member so that the motor may turn the driven member. With the arm in the active position, the pin no longer couples the output gear and the drive member and the latter may be turned manually by the crank arm independently of the gear train. When the sash reaches either the fully open or fully closed position by power actuation, the motor stalls and the stall current is sensed to stop the motor and reverse the latter momentarily to relieve the torque in the gear train. |
