Abstract: A linear actuator for providing linear motion of an output shaft member and automatically disconnecting the shaft from a gear train comprising a rotatable shaft adapted to be coupled to an electrically powered gear train for causing rotation of the shaft; a shaft member mounted onto the rotatable shaft and axially moveable between a retracted position and an extended position in response to rotation of the shaft; a rotatable screw co-acting with the gear train to rotate in response to movement of the gear train; a second member mounted on the rotatable screw and axially moveable in response to rotation of the screw between the retracted position and the extended position; a switch unit located at at least one of the extended and retracted positions and responsive to engagement with the moveable second member for causing an electrical disconnection between the gear train and a power source to cause termination of shaft rotation; and a member coupled to the rotatable shaft for disconnecting the shaft from the g