What is a starter motor ? A starter (also self-starter, cranking motor, or starter motor) is a device used to rotate (crank) an internal-combustion engine so as to initiate the engine's operation under its own power. Starters can be electric, pneumatic, or hydraulic. The starter motor can effectively reduce manpower requirements, and is more rapid and reusable. It is often used in the start of automobile engines and the start of large construction machinery.