# US 8,061,954 B2 · Cargo door/ramp lift assist system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,061,954 B2 - Document ID: US8061954B2 - Status: Granted - Kind: B2 - Application number: 11/619,321 - Filed: 2007-01-03 - Published: 2007-08-09 - Granted: 2011-11-22 - Earliest claimed: 2006-01-03 - Assignees: Designed Components, LLC - Inventors: Michael Lambright - Web page: https://patentgrep.com/patent/US8061954B2 ## CPC - B60P 1/438: {with means for balancing the weight of the ramp between use and non-use position} - B60P 1/435: {the ramp being attached to or making part of the side- or tailboards of the vehicle} - B60P: VEHICLES ADAPTED FOR LOAD TRANSPORTATION OR TO TRANSPORT, TO CARRY, OR TO COMPRISE SPECIAL LOADS OR OBJECTS (vehicles with special provisions for transporting patients or disabled persons, or their personal conveyances A61G3/00) ## Abstract A lift assist system for cargo door ramps of trucks and trailers which includes one or more torsion arms that are housed in a tubular housing assembly attached at the pivotal axis of the door ramps. The housing assembly includes left and right door hinges and at least one center door hinge. Tubular housing members which house the torsion bars extend between the door hinges. ## Claims ### Claim 1 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. ### Claim 2 (depends on 1) A lift assist system for a cargo door ramp according to claim 1, wherein the tubular housing comprises two frame tubes. ### Claim 3 (depends on 1) A lift assist system for a cargo door ramp according to claim 1, wherein the at least one torsion bar comprises two torsion bars and the at least one center door hinge comprises two center door hinges. ### Claim 4 (depends on 1) A lift assist system for a cargo door ramp according to claim 1, wherein the door ramp comprises a vehicle door. ### Claim 5 (depends on 1) A lift assist system for a cargo door ramp according to claim 1, wherein the door ramp comprises a trailer door. ### Claim 6 (depends on 1) A lift assist system for a cargo door ramp according to claim 1, wherein the plurality of door hinges comprise a plurality of door supports that include tubular portions and mounting plates and the tubular housing extends through the tubular portions of the door supports. ### Claim 7 (depends on 6) A lift assist system for a cargo door ramp according to claim 6, wherein the plurality of door supports comprises door supports on opposite ends of the lift assist system and at least one intermediate door support that is positioned between frame mounts through which the tubular housing extends. ### Claim 8 (depends on 7) A lift assist system for a cargo door ramp according to claim 7, further comprising tubular bearings located between the tubular housing and the plurality of door supports and between the tubular housing and the frame mounts. ### Claim 9 (depends on 6) A lift assist system for a cargo door ramp according to claim 6, further comprising tubular bearings located between the tubular housing and the plurality of door supports. ### Claim 10 (depends on 1) A lift assist system for a cargo door ramp according to claim 1, further comprising bracing tubes that are located between the tubular housing and the torsion bar. ### Claim 11 A vehicle having a door that pivots adjacent a frame downward into an open position and upward into a closed position in combination with a lift assist system which combination 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 portion of the frame adjacent which the door pivots between the open and closed positions; a plurality of door hinges attached to the door, 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, the tubular housing being attached to the frame, 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. ### Claim 12 (depends on 11) The combination of claim 11, wherein the tubular housing comprises two frame tubes. ### Claim 13 (depends on 11) The combination of claim 11, further comprising a tension bar stop secured to the frame into which the opposite end of the torsion bar is received. ### Claim 14 (depends on 11) The combination of claim 11, wherein the at least one torsion bar comprises two torsion bars and the at least one center door hinge comprises two center door hinges. ### Claim 15 (depends on 14) The combination of claim 14, further comprising a pair of tension bar stops secured to the frame between the two tension bars into which the opposite ends of the tension bars are received. ### Claim 16 (depends on 11) The combination of claim 11, wherein the vehicle comprises a motorized vehicle. ### Claim 17 (depends on 11) The combination of claim 11, wherein the vehicle comprises a non-motorized towed vehicle. ### Claim 18 (depends on 11) The combination of claim 11, wherein the plurality of door hinges comprise a plurality of door supports that include tubular portions and mounting plates and the tubular housing extends through the tubular portions of the door supports. ### Claim 19 (depends on 18) The combination of claim 18, wherein the plurality of door supports comprises door supports on opposite ends of the lift assist system and at least one intermediate door support that is positioned between frame mounts through which the tubular housing extends. ### Claim 20 (depends on 18) The combination of claim 18, further comprising tubular bearings located between the tubular housing and the plurality of door supports.