Commutators are used in direct current (DC) machines: dynamos (DC generators) and many DC motors as well as universal motors. In a motor the commutator applies electric current to the windings. By reversing the current direction in the rotating windings each half turn, a steady rotating force (torque) is produced.To keep the torque on a DC motor from reversing every time the coil moves through the plane perpendicular to themagnetic field, a split-ring device called a commutator is used to reverse the current at that point.