Shock absorbers are divided into five types: hydraulic shock absorbers, inflatable demand reducers, twin tube shock absorbers, single tube shock absorbers, and resistance adjustable shock absorbers.

(1) Hydraulic type

Hydraulic shock absorbers are widely used in automotive suspension systems. The principle is that when the frame and axle make reciprocating relative motion and the piston moves back and forth in the cylinder of the shock absorber, the oil in the shock absorber housing repeatedly flows from the inner cavity through some narrow pores into another inner cavity. At this point, the friction between the liquid and the inner wall, as well as the internal friction of liquid molecules, form a damping force on the vibration;

(2) Inflatable type

Its structural feature is that a floating active cold is installed at the lower part of the cylinder, and high-pressure hydrogen gas is filled in a closed chamber formed by the floating piston and one end of the cylinder;

(3) Double tube type

The shock absorber has two inner and outer cylinders. The piston moves in the inner cylinder, and the volume of oil in the inner cylinder increases and contracts with the entry and extraction of the working plug rod. Therefore, it is necessary to maintain the balance of oil in the inner tube by exchanging with the outer cylinder. So there should be four valves in the double tube shock absorber, namely, 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 tubes to complete the exchange function;

(4) Single tube type

Compared with the double tube type, the single tube type shock absorber has a simpler structure and reduces the need for a valve system. It is equipped with a floating piston at the lower part of the cylinder tube (the so-called floating refers to the absence of a piston rod to control its movement), forming a closed chamber under the floating piston, filled with high-pressure atmosphere;

(5) Adjustable resistance shock absorber

It can change the size of the throttle hole through external operation. Recently, electronic control shock absorbers have become standard equipment in cars. By detecting the driving status through sensors and calculating the damping force through a computer, the damping force adjustment mechanism on the shock absorber automatically works.