An electrical starter is the core component of the starting system. The starter is mainly composed of the DC starter motor, transmission mechanism and control device. 

Auto Starter

1- solenoid switch, 2- contacts, 3- battery terminal, 4- movable contact, 5- DE housing, 6- brush spring, 7-commutator, 8- carbon brushes, 9- field case, 10– magnetic pole, 11- armature, 12- field windings, 13-guide ring, 14- thrust ring, 15- overrunning clutch, 16- armature shaft, 17- drive gear, 18- transmission mechanism, 19- brake discs, 20-engagement spring, 21- shift lever, 22- plunger, 23- return spring, 24- solenoid switch

Starters used on different models of cars have different forms, but the DC motors are similar. The main difference lies in the transmission mechanism and control device.

1)The function of DC starter motor is to convert electrical energy into mechanical energy, to produce electromagnetic torque.

2)The function of transmission mechanism, also known as starter clutch or engagement clutch is to force the drive gear on the starter armature to mesh with the flywheel ring gear. After starting the engine, the starter clutch allows the drive gear of the start to disengage from the flywheel ring gear. 

1)The control device is functioned as a starter switch to energize and de-energize the starter to battery circuit. In the meanwhile, the switch-on and-off of the additional ignition coil resistance is also controlled by the control device.