Shock absorber assembly is mainly used to suppress spring rebound after the quake absorption of shock and impact from the road, to counter the torsional vibration of crankshaft crankshaft by cylinder (i.e., the impact of the ignition and twisting phenomenon).

Suspension system because of the elastic element in the impact vibration, to improve automobile riding comfort, installed in parallel with the elastic element in the suspension shock absorber, for attenuation vibration, shock absorption system generally adopts the hydraulic shock absorber, its working principle is that when the frame (or body) and the vibration appears when the relative motion between axle, shock absorber piston to move up and down, the oil shock absorber cavity and it repeatedly from one cavity through different pore flow into another cavity.

The structure of the shock absorber is inserted into the cylinder with piston rod and filled with oil. There are throttling holes in the piston, so that the oil in the two parts of the space separated by the piston can complement each other. The damping is when the viscous oil is produced through the throttle orifice, the smaller the throttle hole, the larger the damping force, the greater the viscosity of the oil and the greater the damping force. If the throttle hole size is constant, when the shock absorber works fast, the damping will affect the absorption of the shock. [1]

The shock absorber and elastic element bear the task of cushioning shock and shock absorption, and the damping force is too large, which will cause the suspension elastic to deteriorate, and even damage the connection of the shock absorber. So there is a need to adjust the tension between the elastic element and the shock absorber.

(1) in the compression stroke (the axle and frame are close to each other), the damping force of the shock absorber is relatively small, so as to give full play to the elastic part of the elastic element and mitigate the impact. At this point, the elastic components play a major role.

(2) in the span of suspension, the damping force of the shock absorber should be large and the damping force should be reduced rapidly.

(3) when the axle wheel (or) and the relative speed between the axle is too large, the shock absorber can automatically increase liquid flow rate, and the damping force is always keep within limits, in order to avoid too much under impact load.