1. (Jiusheng spring) controls the movement of machinery, such as valve springs in internal combustion engines, control springs in clutches, etc.
2. Ability to absorb vibration and impact, such as automobiles , buffer springs under train carriages, shock-absorbing springs in couplings, etc.
3. Store and output energy as power, such as clock springs, springs in firearms, etc.
4. Used as force measuring original components such as dynamometers, springs in spring scales, etc. The ratio of the load to the deformation of the spring is called the spring stiffness. The greater the stiffness, the harder the spring.