Abstract: A selectively engageable motor-drive assembly operable for moving a vehicle door or ramp to enable manual operation or motorized operation is provided, having a motor, a pulley drawing a cable attached to the door or ramp, a torque-multiplying arrangement positionable between a fully-engaged position and a partially-disengaged position, and an actuator mechanism for positioning the torque-multiplying arrangement in accordance with a selection of manual or motorized operation. The actuator mechanism may be actuated by a solenoid that is activated by an operator through a control unit. Also, a cam may be provided to define the movement of the actuator mechanism.

Abstract: A releasable drive mechanism is provided, having a sprocket and gear rotatable about a central axis, the gear being rotatably secured to a shaft extending along the central axis. The sprocket and the gear are each configured to provide a coplanar portion extending parallel with the central axis that interfaces the surface of the other. A clutch engageable with the sprocket and the gear is provided, having projections or keys being positionable between the interfacing surfaces for releasably coupling the sprocket and the gear for joint rotation. A lever is provided for disengaging the clutch and the clutch may be biased to facilitate engagement of the clutch. A clip may also be provided to prevent lateral movement of the sprocket on the shaft when the clutch is disengaged.