There are many designs of motors, although they usually contain three parts: a rotor, a stator, and a inverter. These three parts use electromagnetic attraction and repulsion, causing the motor to keep rotating, as long as it receives a stable current.
The motor works by electromagnetic principles. If you run an electric current through a wire, it will create a magnetic field. If you wind a wire around a pole and run an electric current through the wire, it will create a magnetic field along the pole. The pole will have a passive pole at one end and a south pole at the other end. Opposite poles will attract each other, and similar poles will repel. When you surround a pole with other magnets, the pole will rotate due to attractive and repulsive forces.
Every motor has two necessary parts: one is stationary and the other is rotating. The stationary part is the stator. Despite the different configurations, the stator is usually a permanent magnet or magnets arranged on the edge of the motor housing, which is usually a circular plastic drum.
Embedded in the stator is the rotor, which is usually composed of copper wire wound into a coil. When current flows through the coil, the corresponding magnetic field pushes the magnetic field created by the stator and causes the shaft to rotate.
Inverter: the basics
A motor has another important part, the inverter, which is at the other end of the coil. It is a metal ring divided into two halves. Every time the coil rotates half a turn, it reverses the current in the coil. The inverter periodically rotates the rotor and the external circuit, or the current of the battery. This ensures that the end of the coil does not move in the opposite direction, and ensures that the shaft rotates in one direction.
More inverters: magnetic poles
The inverter is necessary because the rotating rotor obtains movement from the attraction and repulsion between the stator and the rotor. To understand this, imagine that the motor is rotating at a slow speed. When the rotor turns to this point, the rotor turns to the point where the south pole of the rotor magnet meets the north pole of the stator, and the gravitational force between the two poles will stop the rotation. In order to ensure that the rotor rotates, the inverter reverses the polarity of the magnet, so the south pole of the rotor becomes the north pole. The north pole of the rotor and the south pole of the stator repel each other, so that the rotor continues to rotate.
Carbon brush and terminal
At one end of the DC gear motor
is the carbon brush and terminal. They exist at the other end, and the rotor exists at the end of the motor housing. The carbon brushes transfer current to the inverter and are made of graphite. The terminal is where the battery is attached to the motor and sends current to spin the rotor.