A carbon brush, also known as a motor brush, is the small part of the motor that conducts electrical current between the stationary wires (stator) and the rotating wires (rotor) of a motor or generator. The brush is typically made up of one or more carbon blocks and can come with one or more shunts or terminals. How does a carbon brush work on a DC motor? In dc motors, the carbon brush makes sure the commutation process remains free from sparks. This contact is a sliding contact capable of transmitting electric current from static to the rotating part of a generator or electric motor. A single or several carbon blocks composes a brush. What is the function of the carbon brush? A brush or carbon brush is an electrical contact which conducts current between stationary wires and moving parts, most commonly in a rotating shaft. Typical applications include electric motors, alternators and electric generators.