What a starter motor actually does
A starter motor spins the engine until it fires. The solenoid closes the high-current circuit and pushes the pinion. A clutch lets the engine overrun.
Key or button. A thin wire to the solenoid. That is not the crank. The starter is a high-current motor bolted to the bellhousing. It is not an alternator. The belt does not turn this case. This case turns the engine until it can breathe.
The solenoid does two jobs. It slams the high-current contacts so battery current can reach the armature. The same plunger shoves the pinion out of the nose so those teeth land in the flywheel ring. One click, two motions. No click and no crank is often that solenoid or the fat cable that feeds it. A grind is the pinion and the ring missing each other.
The armature spins the pinion. The engine turns. Once it fires it is faster than this motor. The overrunning clutch — Bendix — lets the ring overrun the pinion so the starter does not get driven. Free-spin with no crank is that clutch. The key comes back. The plunger drops. The pinion retracts. The fat circuit opens. That is the start. Then the belt-driven case takes over.
