① control the movement of machinery, such as internal combustion engine in the valve spring, clutch control spring and so on.
② absorb vibration and shock energy, such as cars, train cars under the buffer spring, the coupling in the vibration spring and so on.
③ storage and output energy as a driving force, such as clocks and springs, spring in the firearms and so on.
④ used as force components, such as dynamometer, spring scales in the spring and so on. Spring load and deformation ratio is called the spring stiffness, the greater the stiffness, the harder the spring
