Automobile suspension is a device that elastically connects the frame and the axle in an automobile. It is generally composed of elastic elements, guide mechanisms, shock absorbers and other components. Its main task is to mitigate the impact transmitted to the frame from the uneven road surface to improve the riding comfort:

1. The automobile suspension consists of three parts: elastic element, shock absorber and force transmission device. These three parts play the roles of cushioning, damping and force transmission respectively;

2. Coil spring: it is the most used spring in modern cars. It has strong shock absorption ability and good riding comfort; The disadvantages are that the length is large, the occupied space is large, and the contact surface of the installation position is large, which makes it difficult to compact the layout of the suspension system. Because the coil spring itself can not bear the lateral force, it is necessary to adopt the complex combination mechanism such as four-bar coil spring in the independent suspension;

3. Leaf spring: it is mainly used for van and truck, and is composed of several long and thin spring plates with different lengths. It is simpler in structure and lower in cost than the coil spring, and can be compactly assembled at the bottom of the vehicle body. Friction is generated between each piece during operation, so it has attenuation effect. However, if severe dry friction occurs, the ability to absorb impact will be affected. Modern cars that attach importance to riding comfort are rarely used;

4. Torsion bar spring: it is a long bar made of spring steel with torsion rigidity. One end is fixed to the vehicle body and the other end is connected to the upper arm of the suspension. When the wheel moves up and down, the torsion bar will twist and deform, acting as a spring.