Dual trailing arm vehicle suspension

Abstract

A suspension system for a vehicle includes a longitudinally extending frame, an axle connected to the frame for relative movement with respect thereto, an air spring mounted between the frame and the axle to yieldably support the axle with respect to the frame, and upper and lower trailing arms attached to each side of the frame. A first torsion bar extends between and is rigidly attached to the upper trailing arms and a second torsion bar extends between and is rigidly attached to the lower trailing arms. The torsion bar cooperates with the springs during deflection of the suspension system with respect to the frame to thereby yieldably resist relative movement between the trailing arms and the frame. In one embodiment, the upper and lower trailing arms are parallel to each other. This arrangement results in load equalization between the suspension assemblies. Any relative torque caused by deflection of the trailing arms is equally distributed between both torque bars. In another embodiment, the upper and lower trailing arms are non-parallel, and arranged such that when the trailing arms pivot due to road conditions or vehicle loading, fore and aft movement of the air spring and axle due to arcuate swing of the trailing arms is minimized.