The powered ramp door lift is used in cargo trailers and other ramp door applications and includes a powered winch assembly, a pair of wire cables or nylon straps connecting the winch assembly to the ramp door, and a "pusher" mechanism. The winch assembly mounted to the trailer header winds and unwinds the cables onto a pair of spools mounted to a drive shaft, which is driven by an electric motor. The "pusher" mechanism prevents the "unspooling" problems that effect the operation of winches in automated ramp door applications. The pusher mechanism engages the ramp door in the closed position and applies an outward force to the ramp door over a small portion of its travel to assist in the initial lowering of the ramp door from the closed position. The winch assembly also includes a cable tension winch shut off mechanism, which deactivates the winch motor in the absence of any tension on cables.

A cable slackness monitoring device has a pull cord to detect movement of support pins associated with the cables. In the case of a slack cable the support pin moves downwardly relative to a carrier frame. Fixedly clamped between a nut and a locknut is a trigger element which engages the pull cord in the case of movement of the support pin. The pull cord is fixed at one end to a fixing point of a bracket, and is, and is connected at the other end to a displaceable slide. The deflection of the taut pull cord caused by the movement of the support pin moves the slide, actuating a limit value detection.