Patent ID: 8061954

Claim:
A lift assist system for a cargo door ramp that comprises: at least one torsion bar that has one end fixed against axial rotation relative to the door ramp and an opposite end fixed against axial rotation relative to a structure about which the door ramp pivots between an open and closed position; a plurality of door hinges including at least left and right door hinges and at least one center door hinge; and a tubular housing extending between the door hinges through which the at least one torsion bar extends, wherein the one end and the opposite end of the at least one torsion bar each have cross-sectional shapes that are complimentarily shaped so as to mate with and be received in a bore or through-hole provided in a structural element that fixes the one end of the at least one torsion bar to a door ramp and in a bore or through-hole that fixes the opposite end of the at least one torsion bar to a structure adjacent to the door ramp whereby when the one end and the opposite end of the at least one torsion bar are received in the bores or through-holes the one end of the at least one torsion cannot be rotated with respect to the structural element and the opposite end of the at least one torsion bar cannot be rotated with respect to said structure adjacent to the door ramp.