Cargo ramp hoist mechanism

Abstract

A portable hoist mechanism which is configured for temporary installation proximate the cargo opening of an aircraft to facilitate the loading and unloading of a cargo ramp is disclosed. The hoist mechanism includes a rectangular base unit that is placed on the floor of the aircraft cargo compartment and structurally interconnected with the aircraft sill fittings and end locks of the aircraft cargo handling system. An A-frame, having a cable sheave mounted at the apex thereof, is pivotably attached to the forward portion of the base unit upper surface in an orientation which permits the upper end of the A-Frame to be swung outwardly through the aircraft cargo opening. A ball screw actuator, extending angularly from the central region of the A-frame to the rear portion of the base unit upper surface, is operable to selectively position the A-frame during loading and unloading of a cargo ramp. In operation, the first end of a cable assembly is threaded through the A-frame cable sheave and connected to a winch of the aircraft cargo handling system. A bridle, at the second end of the cable assembly, is interconnected with the upper end of the cargo ramp and the cargo system winch and ball screw are operated to raise or lower the upper end of the cargo ramp between ground level and guide channels that are mounted on the floor of the cargo compartment for receiving the cargo ramp. During this operation, the ball screw is utilized to swing the A-frame so that the upper end of the cargo ramp does not strike the aircraft and the cargo system winch is utilized to raise and lower the upper end of the cargo ramp between the ground and the sill region and to move the upper end of the cargo ramp into or out of the guide channels.