A torsion spring is a ribbon, bar, or coil that reacts against twisting motion.

Torsion ribbons are used in torsion pendulum clocks , where a weight is spun, oscillating in its spinning direction at the bottom of the clock. As the resonant period is very long, this mechanism is used in spring wound clocks designed to operate for an entire month or even a year without rewinding. This type of suspension is also used in sensitive devices used to determine constants associated with the gravitational effects of mass.

Torsion bars (or sway bars) are used to support automobile suspension components, allowing those components (which indirectly support the wheels) to move in response to rough roads while allowing a smooth ride in the vehicle. The DeLorean DMC-12 uses cryrogenically tempered torsion bars to assist with the opening of its gull wing doors.

Large coiled torsion springs are used to counter-balance the weight of garage doors. Great care must be exercised when adjusting these as they store a large amount of mechanical energy.

Small coiled torsion springs are often used to operate small pop-up doors such as are found on small consumer goods such as digital cameras and compact disk players.

See also: torque