Editing Coil spring (section)

== Variants ==
[[File:Sherman chen.jpg|thumb|[[Volute spring]] suspension on an [[M4 Sherman]] tank]]

Types of coil spring are:

* Tension/extension coil springs, designed to resist stretching. They usually have a hook or eye form at each end for attachment.
* Compression coil springs, designed to resist being compressed. A typical use for compression coil springs is in [[car]] [[Suspension (vehicle)|suspension systems]].
** [[Volute spring]]s are used as heavy load compression springs. A strip of plate is rolled into the shape of both a helix and a spiral. When compressed, the strip is stiffer edge-on than a wire coil, but the spiral arrangement allows the turns to overlap rather than bottoming out on each other.
**[[Arc spring|Arc springs]] (bow springs) are a special form of coil spring which was originally developed for use in the [[dual-mass flywheel]] of internal [[Internal combustion engine|combustion engine]] drive trains. The force is applied through the ends of the spring. A torque <math>M=F\cdot r</math> can be transmitted around an axis via the force <math>F</math> directed along this helical axis and the lever arm to the system center point <math>r</math>.
* Torsion springs, designed to resist twisting actions. Often associated to clothes pegs or up-and-over garage doors.