Abstract: The flip gear of the light truck suspension is the use of the torque of the torque to offset the gravity moment of the cab to reverse the bridge. The common problem in the industry is that the stress of the torque of the torque of the light truck exceeds the yield limit of the spring steel, which causes the torsion force to decay. The single-torsion switch mechanism is not allowed to cause the bridge deflection of the bridge to cause the suspension of the bridge and the interference of the cab and the carriage. Based on the theory of mechanics and simulation simulation, the validity of the suspension design method is verified by the optimal torsion rod diameter and the bridge, and the industry standard of the bridge is less than 280 N, and the prediction of the predeflection value of the bridge is realized, and the safety and the concept of light truck are guaranteed.