A DC shunt motor is an electric motor powered by direct current where the field windings are connected in parallel to the armature windings. This allows both coils to be powered by the same source.
Also known as a constant speed or constant flux motor, a characteristic of a shunt motor is its ability to maintain a constant speed under different loads without the use of a speed regulating control device. The motor regulates its own speed by taking advantage of its internal resistance. Its turning armature creates an electromagnetic field which is the source of the resistance. By applying a load to the motor, the armature slows and the resistance is reduced, giving it more strength. The balance of load to resistance allows the motor to maintain a constant speed. To change the speed of the motor a change in current from its power source is required.
Visually, a shunt motor can be distinguished by examining the armature. The armature of a shunt motor consists of a large number of coils made of thin wire for increased resistance. Other types of DC motors are constructed of heavier thicker coils. The higher number of coils increases the torque or strength of the motor.