The carbon brushes developed by a k motiwala, have high hardness, material strength and pronounced cleaning action that provides longer brush life under severe operating conditions. These brushes may not commutate, that is reverse the direction of [an alternating electric current] each half cycle so as to produce a unidirectional current. The grades of these carbon brushes are limited to lower current densities and are used on slower machines, particularly those with flush mica commutators. These brushes generate high friction. The features of the carbon brushes are as follows: higher strength and hardness, low resistance, suitable for machines that require some polishing action.
