In DC Motors, interconnect element used to apply voltage to rotor windings that are the moving part of motor is called engine coal, while the rotor part with
which Engine Coal contacts is called collector or commutator.
In DC Motors, tension is applied to the rotor windings inside the magnetic field formed in stator and current passes over the winding conductor. Force is applied to the conductor that is in the magnetic field and over which current passes. With the effect of this force, the conductor (rotor) moves. The tension applied to the rotor should not interrupt in order for the continuous movement of the rotor to continue without interruption.
The interrupted tension is ensured by Engine Coals. The hardness of is very important. If the coal is hard, then the collector may corrode and deform over time. Thus, any shortened Engine Coals should be replaced and any deformation on the collector should be fine grained.