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.

Constant force spring is made by winding the steel strip into a coil which exerts a nearly constant retraining force to resist uncoiling. By comparing the differences between constant force spring and traditional wire springs, the advantages will be obtain as following: To exert nearly constant force during entire extension. Short initial deflection, it means that reaching the rated load at short extension. Long extension capability. The product range from 0.03~0.75mm in thickness and 1~50mm in width.