Starter ring gear

A starter ring gear is a part attached to an internal combustion engine that is part of the assembly which transfers the torque from the starter motor to the engine's crankshaft, in order to start the engine. The starter ring gear is usually made from medium carbon steel.

Starter ring gears are attached to either the flywheel or the flexplate of an engine. The teeth of the ring gear are driven by the smaller gear (known as the pinion) of the starter motor. The pinion engages the starter ring only during starting and once the engine is running the pinion withdraws.