Electromagnetic dc motor is composed of stator magnetic pole, rotor (armature), commutator (commonly known as commutator), brush, housing, bearing, etc.

The stator magnetic pole (main magnetic pole) of electromagnetic dc motor is composed of a core and an excitation winding. It can be divided into series excitation dc motor, parallel excitation dc motor, other excitation dc motor and compound excitation dc motor. Due to different excitation modes, the stator magnetic flux (generated by the excitation coil of stator magnetic pole) is different.

The commutator piece is made of alloy materials such as silver copper, cadmium copper and moulded with high-strength plastics. The brush slides in contact with the commutator to provide armature current to the rotor winding. Electromagnetic dc motor brush generally uses metal graphite brush or electrochemical graphite brush. The core of the rotor is formed by superimposed silicon steel sheets, which are generally 12 slots, embedded with 12 sets of armature windings. After the windings are connected in series, they are connected with 12 commutator pieces respectively.