Leaf spring: by a number of unequal length and unequal curvature of the steel plate. When installed, both ends will bend upward naturally. When the impact of the road surface on the wheel comes, the steel plate is deformed, which plays a role of buffering and damping. The longitudinal layout also has the role of guiding the force transmission. The independent suspension is mostly made of leaf spring as the elastic element, which can save the guide device and shock absorber, and has a simple structure.