Shock absorbers are divided into five types: hydraulic shock absorbers, pneumatic shock absorbers, twin-tube shock absorbers, monotube shock absorbers, and adjustable resistance shock absorbers.

(1) Hydraulic type

Hydraulic shock absorbers are widely used in automotive suspension systems. The principle is that when the frame and the axle reciprocate relative to each other and the piston reciprocates in the cylinder barrel of the shock absorber, the oil in the shock absorber housing repeatedly flows from the inner cavity through some narrow pores into the other inner cavity. At this time, the friction between the liquid and the inner wall and the internal friction of the liquid molecules form a damping force on the vibration.

(2) Inflatable

Its structural characteristics are that the lower part of the cylinder barrel is equipped with a floating live cold, and a closed air chamber formed at one end of the floating piston and the cylinder is filled with high-pressure hydrogen;

(3) Double-barrel type

The shock absorber has two cylinders, the inner and outer cylinders, the piston moves in the inner cylinder, and the volume of oil in the inner cylinder increases and contracts by the entry and withdrawal of the dry piston rod, so it is necessary to maintain the balance of the oil in the inner tube by exchanging with the outer cylinder. Therefore, there should be four valves in the double-barrel shock absorber, that is, in addition to the two throttle valves on the piston mentioned above, there are also flow valves and compensation valves installed between the inner and outer cylinders to complete the exchange effect;

(4) Monotube

Compared with the double-barrel type, the single-barrel shock absorber has a simple structure and reduces one set of valve systems. It is equipped with a floating piston in the lower part of the cylinder tube, (the so-called floating means that there is no piston rod to control its movement), and a closed air chamber is formed under the floating piston, which is filled with high-pressure atmosphere;

(5) Drag adjustable shock absorber

It can be operated externally to change the size of the throttle. Recent automobiles have electronically controlled shock absorbers as standard equipment, which detect the driving status through sensors, and the damping force is calculated by a computer, so that the damping force adjustment mechanism on the shock absorber works automatically.