Device and description of the starter

The car has a starter type 57.3708 (or its modification), which is a DC motor with permanent magnet excitation and an integrated planetary gear. A traction relay is installed on the starter motor housing.

The engine armature shaft and the starter drive shaft rotate in bronze-graphite bushings, which are installed in the rear and front covers of the starter, in the armature shaft support and in the drive shaft support. The armature shaft transmits rotation to the drive shaft through a planetary gearbox. The planetary gears of the starter reducer rotate on needle bearings.

The starter drive consists of a drive gear and an overrunning clutch. The drive can move along the helical splines of the drive shaft.

The starter traction relay is designed for remote switching of the high current consumed by the starter when starting the engine, and for the mechanical connection of the starter drive with the engine flywheel ring gear. The starter traction relay coil has two windings, retracting and holding.

When the ignition key is turned to position «starter» to the control output of the traction relay «50», and from it voltage is supplied to both windings of the relay from the battery. Under the influence of a magnetic field, the metal core of the traction relay, overcoming the force of the return spring, is drawn into the coil. At the same time, it drives the starter drive lever. The drive lever, with its horseshoe-shaped fork, extends the starter drive, introducing the drive gear into engagement with the engine flywheel ring gear. At the same time, a copper contact plate located in the plastic cover of the traction relay closes the contact bolts. Current begins to flow through the starter armature windings and the armature rotates, starting the engine.


The negative terminal of the retracting winding of the traction relay is connected to «weight» through the starter armature windings (see diagram). After closing the contact bolts, the current stops flowing through this winding, and the core of the traction relay is held by only one winding, this makes it possible to reduce the heating of the traction relay windings and reduce the power consumption at the time of starting the engine.

The overrunning roller clutch of the drive transmits rotation only in one direction - from the starter to the flywheel. After starting the engine, when the crankshaft speed increases sharply, the clutch protects the starter from destruction.

After the driver releases the ignition key, the output of the starter traction relay stops receiving control voltage, the electromagnetic field holding the armature disappears. The drive lever, under the influence of a spring, moves the starter drive back and disengages the drive gear from the flywheel crown. At the same time, the power contacts open, supplying current to the starter motor windings.

Warning. The starter is the most powerful consumer of electrical energy in a car. When starting the engine, the current consumed by the starter can reach more than 400 A. Therefore, all electrical connections between the battery and the starter must be in good and reliable contact.

Helpful advice. Do not turn on the starter for more than 15 seconds. Between attempts to start the engine, pause for 20-30 seconds. If the engine does not start after three attempts, you need to find out what is the cause and eliminate it.

Note. On cars of recent years of production in the starter circuit (between the traction relay and the ignition switch) an additional relay is installed.