Hydraulic suspension is widely used in automotive suspension systems. The principle is that when the frame reciprocates relative to the axle and the piston reciprocates in the cylinder of the shock absorber, the oil in the shock absorber housing repeatedly flows into the narrow bore through the narrow cavity into the other A cavity. At this moment, the friction between the liquid and the inner wall and the inner friction of the liquid molecules form a damping force against vibration.
Inflatable shock absorber is developed since the 1960s a new type of shock absorber. The structure is characterized in that a floating piston is arranged at the lower part of the cylinder barrel and a sealed gas chamber formed at one end of the floating piston and cylinder barrel is filled with high-pressure nitrogen gas. The floating piston is equipped with a large cross-section of the O-ring, which completely separate oil and gas. The working piston is equipped with a compressing valve and a stretching valve that change the cross-sectional area of the passage as the speed of movement. When the wheel bounces up and down, the working piston of the shock absorber reciprocates in the oil, causing a hydraulic pressure difference between the working piston's upper chamber and the lower chamber. The pressure oil pushes the compression valve and the expansion valve back and forth. As the valve on the pressure oil have a greater damping force, the vibration attenuation.