A starter (also self-starter, cranking motor, or starter motor) is a device used to rotate (crank) an internal-combustion engine so as to initiate the engine's operation under its own power. Starters can be electric, pneumatic, or hydraulic. In the case of very large engines, the starter can even be another internal-combustion engine.
The function of the starter motor is to start up the combustion engine. An electric motor forms the basis of the starter motor. When the starter switch is turned on, the starter relay turns on the electric motor. This motor drives the starter gear ring via the pinion gear. The rotating movement of the starter motor is created through the interaction of two magnetic fields. Starter motors come with permanent magnets or with electromagnets. Each of these configurations has its own specific characteristics.