What is the primary function of brushes in an electric motor?

The primary function of brushes in an electric motor is to maintain electrical contact. Brushes are typically made of conductive materials such as carbon and are designed to press against the commutator in a DC motor or against the rotor in an AC motor. This contact allows electrical current to flow into the rotating part of the motor, enabling it to generate the magnetic field required for rotation.

In a typical scenario, as the motor spins, the brushes ensure that there is a continuous electrical connection, allowing the motor to operate smoothly and efficiently. Without the brushes, the electrical connection would be intermittent or non-existent, leading to the motor not functioning properly.

While cooling the motor is important for overall performance, the brushes primarily facilitate the essential electrical connection that makes motor operation possible. Supporting the rotor and increasing efficiency may be secondary benefits in some designs, but the fundamental role of brushes is indeed to maintain that vital electrical contact between stationary and rotating parts.