Starter motors

A starter motor is used to turn the engine over. When cars first came out this would be done by hand. A ‘crank handle’ would slot into the crank and you would turn the engine over yourself. Then inertia starter motors came out. This type of starter motor uses a spiral mechanism to engage into the ring gear while pinion gear was already spinning. Problem with this is that if starter didn’t receive enough power, it wouldn’t spin the pinion gear fast enough. Resulting in gears crunching and worn ring gear over a short period. Another type of starter motor is gear reduction. These are often used in higher compression engines due to the added load on the starter. They work similar to a pre engaged starter but consist of more gears. These added gears provide a higher torque from starter.  In today’s cars the most popular type of starter motor is pre engaged. This type of starter motor engages into the ring gear before spinning. It does this with the use of a solenoid. Pull in windings activate a plunger which pushes the pinion gear into the ring gear. When the plunger is all the way in the pull in winding power down and hold in windings activate. While this is happening the plunger has connected two contacts together enabling a high flow of electricity to flow to the windings and the armature.

The starter motors principal is to turn electrical energy into mechanical energy. It does this with the use of electro-magnetism.  Because the iron core is surrounded by windings, when the electromagnetic fields cut across each other an electric current is created and absorbed into the windings. The brushes on that push onto the commutator allow electricity to pass through armature. Because the commutator is split into sections it turns windings on and off.  It is this action of turning them on and off that cause the armature to spin.