When the wheel of the car moves close to the body and the shock absorber 1629405 is compressed, the piston in the shock absorber moves downward. The volume of the lower chamber of the piston decreases, the oil pressure increases, and the oil flows through the flow valve to the chamber above the piston (upper chamber). The upper chamber is occupied by the piston rod to take up a part of the space, so the volume of the upper chamber is less than the volume of the lower chamber reduced, part of the oil then push the compression valve, flow back to the oil cylinder. The oil savings of these valves form a damping force for the compressed motion of the suspension. When the alza rear absorber is stretched as the wheel moves away from the body, the piston of the shock absorber moves upwards. The oil pressure in the upper chamber of the piston increases, the flow valve is closed, and the oil in the upper chamber pushes the extension valve into the lower chamber. Due to the existence of the piston rod, the oil flow from the upper chamber is not enough to fill the volume of the lower chamber, the main cause of the lower chamber to produce a vacuum degree, then the oil in the storage cylinder to push the compensation valve flow into the lower chamber to supplement. Because of the throttling function of these valves, the suspension is damped when it is extended.