When we compress stretch shock absorbers at a fixed speed, the resistance produced by them is called damping. This resistance comes the fact that when the shock absorber is actuated, the piston will pressurize the damping oil to make it pass through the valve with small hole diameter. If the manufacturer of gray iron castings changes the hole diameter of the valve, the damping can be changed. According to the Japanese specification for automatic vehicles (jasoc602), the manufacturer of gray iron castings specifies that the performance of shock absorbers is represented by the resistance at the actuation speed of 0.3m/s. We call it the damping coefficient, the unit is KGF. The so-called harder shock absorbers can produce relatively large resistance at the actuation. When we let the shock absorber compress stretch at a very slow speed, its resistance only comes the friction inside the mechanism, the damping oil has little resistance. But when the dynamic speed is increased, the resistance will increase in direct proportion to the square of the change rate of the actuator speed of the shock absorber, that is to say, when the actuator speed is increased to 2 times, the resistance will increase to 4 times.

The resistance of the shock absorber can be divided into two parts: compression rebound. The compression resistance the hardness of the spring have an additive effect. When the spring is actuated, it can increase the strength of the spring. The rebound resistance is the rebound stroke after the spring is compressed by the impact of the road, which is also the reason for the existence of the shock absorber. It is used to resist the force of the spring after compression then press the tire back to the ground, slow down the rebound impact protect it Keep the vehicle stable. Generally speaking, the resistance of shock absorption stroke is much less than that of rebound stroke, because the resistance of shock absorption stroke is too large, which will affect the road comfort. For road vehicles, the ratio of damping force during impact rebound is about 1