A torsional spring is a helical spring that stores and releases angular energy or holds a device statically by rotating a force arm about an axis in the spring. These springs are usually compact, but the coils are spaced apart to reduce friction. They produce resistance to rotation or rotational forces. According to the application requirements, the design of torsion spring rotation (clockwise or counterclockwise), so as to determine the spring rotation.

Spring constant: expressed in terms of K, when the spring is twisted, the load (KGF /mm) is increased by 1° of torsion Angle.

Spring constant formula (unit: KGF /mm) : k=(E X d^4)/(1167 X Dm X P X N X R)

E= Steel modulus of wire: piano wire E=21000, stainless steel wire E=19400, phosphor bronze wire E= 1200, brass wire E= 1200

D= line diameter Do=OD= Di=ID= OD Dm=MD= middle diameter Do-d N= total winding number R= moment arm under load P =3.1416