Abstract: Counterbalance assemblies include a torsion bar spring for counter-balancing the weight of upwardly opening aircraft doors for ease of opening and closing. The torsion bar spring may be linked to the aircraft door through an integrated gear reduction system comprised of two pairs of spur gears and respective shafts as well as a linkage assembly. A cable reel is connected to the output shaft and the input shaft is connected to a four bar linkage system attached to the end of the torsion bar. The cable reel stores the lift cable and provides the output torque to lift the aircraft door. When the aircraft door opens or closes, the center of mass loses or gains height respectively, causing a variation of gravitational potential energy. In such a manner, the gravitational potential energy is exchanged with strain elastic energy from the counter-balance spring therefore reducing the required external source of energy whether it is from a power assisted means or manual operation.

Abstract: Counterbalance assemblies include a torsion bar spring for counter-balancing the weight of upwardly opening aircraft doors for ease of opening and closing. The torsion bar spring may be linked to the aircraft door through an integrated gear reduction system comprised of two pairs of spur gears and respective shafts as well as a linkage assembly. A cable reel is connected to the output shaft and the input shaft is connected to a four bar linkage system attached to the end of the torsion bar. The cable reel stores the lift cable and provides the output torque to lift the aircraft door. When the aircraft door opens or closes, the center of mass loses or gains height respectively, causing a variation of gravitational potential energy. In such a manner, the gravitational potential energy is exchanged with strain elastic energy from the counter-balance spring therefore reducing the required external source of energy whether it is from a power assisted means or manual operation.