Power spring is the steel strip wound on an arbor and confined in a spring case. When a force rotates the spring, arbor will have relative motion with spring case and store rotational energy in the form of torque. When the force is removed, torque releases through the central arbor or the spring case in which it is restrained. The product range from 0.03~0.75mm in thickness and 1~50mm in width.

There are large selections of various springs for brush holders. The advantage of constant force spring for carbon brush are as following: Constant pressure for commutator in any brush length. Increases brush life, reduces electrical wear. Compact design for smaller motor overall diameter that allows longer brushes and larger commutators, featuring reduced spark, lower influence of electromagnetic interference(EMI). The product range from 0.03~0.75mm in thickness and 1~50mm in width.