The document describes the components and operation of a starter motor. The key components are the armature, commutator, brushes, solenoid, plunger, lever fork, pinion, and field coils. When the solenoid is engaged, it pulls the plunger which turns the pinion via the lever fork, transferring the rotational force to the engine flywheel to start the engine. The pinion and lever fork provide a gear reduction ratio between the starter motor and engine for increased torque.