Torsion Springs
Torsion springs are helical springs that exert a torque or rotary force. The ends of a torsion spring are attached to other components, and when those components rotate around the center of the spring, the spring tries to push them back to their original position.
They can store and release angular energy or statically hold a mechanism in place by deflecting the legs about the body centerline axis.
This type of spring is normally close wound but can have a pitch to reduce friction between the coils. They offer resistance to twist or rotationally applied force.