Leaf springs are divided into two forms:

(1) Multi-leaf spring: It is composed of multiple steel plates with different length and same width. The steel plates of multiple leaf springs are superimposed into an inverted triangle shape. The uppermost steel plate is the longest, and the lowermost steel plate is the shortest. The number of steel plates is related to the weight of the passenger car. The thicker and shorter the steel plates are, the greater the spring rigidity is. However, when the leaf spring is used for a long time, the plates will slide and rub against each other to produce noise. The relative friction between steel plates will also cause spring deformation, resulting in uneven driving

(2) Small leaf spring: It is composed of thin steel plates at both ends with middle thickness and equal width and length. The section of the steel plate of the small leaf spring changes greatly, and the section from the middle to the two ends is gradually different. Therefore, the rolling process is more complex and the price is also more expensive than the large leaf spring. Compared with the multi-leaf spring, under the same stiffness (i.e., the same bearing capacity), the less leaf spring is about 50% lighter than the multi-leaf spring, which reduces the fuel consumption and increases the ride comfort. In addition, the point contact between the few leaf springs reduces the relative friction and vibration, and increases the riding comfort