Spiral torsion springs is not contact in any coils, torque delivered per revolution is linear for the first 360°, At greater angular rotations, the coils begin to close on the arbor, and the torque per turn increase rapidly. For this reason, springs of this type are usually used in applications requiring less than 360° of rotation.
If you need special power spring or spiral torsion spring size, our experienced engineers are able to design one that is right for your application.