When there is relative motion between the frame (or body) and the axle due to vibration, the piston inside the shock absorber moves up and down, and the oil in the shock absorber chamber repeatedly flows from one chamber through different pores into another chamber. At this time, the friction between the hole wall and the oil, as well as the internal friction between the oil molecules, form damping forces on the vibration, converting the vibration energy of the car into oil thermal energy, which is then absorbed and emitted into the atmosphere by the shock absorber.

Compression stroke: The axle and frame are close to each other, and the damping force of the shock absorber is small, so as to fully exert the elastic effect of the elastic element and alleviate the impact.

Stretching stroke: The wheels move away from the body of the vehicle, causing the shock absorber to be stretched. The oil pressure in the upper chamber of the piston increases, and the oil pushes open the stretching valve and flows into the lower chamber.

When the speed is too high: When the relative speed between the axle (or wheel) and the axle is too high, it is required that the shock absorber can automatically increase the fluid flow rate to keep the damping force within a certain limit, in order to avoid bearing excessive impact loads.