These are Torsion Spring that exert a rotary force or torque and are subjected to bending stresses. These springs are wound left or right hand so that the deflection causes the spring to wind up from the free position- never to unwind from that position. As the torsion springs wind up they reduce in diameter and their length becomes longer. To see if binding on a supporting rod occurs these changes should be calculated. These types of springs should be supported over a rod when possible. To eliminate coil friction a slight open space should be provided between the coils. This would alter the deflection and torque.
