What is a torsion spring?

A Torsion Spring accumulate rotational energy.

Torsion springs are used to produce torque or accumulate rotational energy in an assembly construction.

A torsion spring is typically mounted on a mandrel. The mandrel is dimensioned so there is just enough of a gap between the mandrel and the inner side of the spring body. There must not be too much or too little gap between the mandrel and the spring body. If there is too much gap, the spring body may collapse, and if there is too little of a gap the spring body may lock onto the mandrel when loaded.

The legs of the torsion spring are fixed to objects that rotate around the central axis of the torsion spring. The torsion spring will attempt to push these objects back to their start position. A torsion spring must always be loaded so that if the wire is "pulled" the spring body will close - as shown in the illustration above.

Torsion springs are stock items, in both right and left-hand wound versions.

The spring shown below is left-hand wound.