Helical spring, is a mechanical device, which is typically used to store energy and subsequently release it, to absorb shock, or to maintain a force between contacting surfaces. They are made of an elastic material formed into the shape of a helix which returns to its natural length when unloaded.A Helical springs can be designed so that each active coil fits within the next coil, so the solid height can be equal to one or two thicknesses of wire. This is useful where the solid height is limited.
These springs offer a constant, or uniform pitch, and have an increasing force rate instead of a constant force rate (regular compression springs). The larger coils gradually begin to bottom as a force is applied. A variable pitch can be designed to give a uniform rate if necessary.
