English: Closeup of an electric motor from a vacuum cleaner, showing the commutator. This is a universal motor that runs on alternating current. The commutator is a rotary switch that supplies power to the rotor windings, reversing the direction of current with each half turn so the magnetic field of the winding exerts a steady torque to turn the rotor in one direction. Labeled parts: (A) commutator, (B) brush, (C) rotor (armature) winding, (D) stator (field) winding, (E) brush guide, , (F) two common power terminals (for all of the stator and rotor windings).
Alteration to original image: changed labels of parts from German to letters.