If a heavy duty starter motor appears to spin when energized but the engine does not turn,which of the following could be at fault?

A) worn pinion gear
B) stripped flywheel ring gear
C) defective starter drive assembly
D) all of the above

Pinion Gear

A small gear that engages with a larger gear or rack, often used in automotive differentials to transfer rotational motion.

Flywheel Ring Gear

A circular gear attached to the outer edge of a flywheel, interfacing with the starter motor to begin engine rotation.

Starter Motor

Electric motor that converts electrical energy from the cranking circuit into the mechanical energy required to start the engine. Also known as cranking motor. Although not common, air-actuated starter motors are also used on trucks.