12 volt DC motor is a rotary motor which can convert the direct current into mechanical energy or convert mechanical energy into DC power. It means that the 12 volt DC motor can interconvert electric energy and mechanical energy. When it is operated as a DC motor, electric energy is converted into mechanical energy.

When as a DC generator, it converts the mechanical energy into electrical energy. 12 volt DC motor is composed of stator and rotor. Stator is still when the motor is working. Its main function is to generate magnetic field. It is composed of a base, a main magnetic pole, a reversing polarity, end cover, a bearing, a brush device and etc.

Rotor is running when the motor is working. Its main function is to generate electromagnetic torque and the induced electromotive force. It is a conversion hub of 12 volt DC motor coverting energy, so it is usually called the armature which is composed of a rotating shaft, an armature core, an armature winding, commutator, fan and etc.