Bosch Starter Motor 0051513901

A starter is a device used to rotate (crank) an internal-combustion engine to initiate the engine's operation under its own power. Internal combustion engines are feedback systems, which, once started, rely on the inertia from each cycle to initiate the next cycle. In a four-stroke engine, the third stroke releases energy from the fuel, powering the fourth (exhaust) stroke and the first two (intake, compression) strokes of the next cycle, as well as powering the engine's external load. To start the first cycle at the beginning of any particular session, the first two strokes must be powered in some other way than from the engine itself. The starter motor is used for this purpose and it is not required once the engine starts running and its feedback loop becomes self-sustaining.

The electric starter motor or cranking motor is the most common type used on gasoline engines and small diesel engines. The modern starter motor is either a permanent-magnet or a series-parallel wound direct current electric motor with a starter solenoid mounted on it. When DC power from the starting battery is applied to the solenoid, usually through a key-operated switch (the ignition switch), the solenoid engages a lever that pushes out the drive pinion on the starter driveshaft and meshes the pinion with the starter ring gear on the flywheel of the engine. Main symptom of a bad starter is that you hear a clicking noise when the key is turned and the engine won't crank.