Torsion Springs

Common torsion springs are used in clothes pins, clipboards, swing-down tailgates and garage doors,. Torsion springs are used for hinges, counterbalances and lever return applications. Sizes range from miniature, used in electronic devices, to large torsion springs used in chair control units.
Load should be applied in the direction of wind; unwinding from the free position is not recommended. As they wind up, torsion springs reduce in diameter and their body length becomes longer. This should be considered when design space is limited. Torsion Springs perform best when supported by a rod or tube. The designer should consider the effects of friction and arm deflection on the torque.