The pinion drive is located in the front part of the drive housing. When the starter is switched on and voltage is supplied to it from the storage battery, the traction repeller located on the starter housing, through the drive engagement lever, extends the pinion along the helical splines on the armature shaft to the toothed ring of the flywheel. As soon as the pinion reaches the stop at the end of the armature shaft, it enters into force engagement with the toothed ring of the flywheel. In this case, the traction repeller turns on the electrical circuit of the starter, and now it can turn the crankshaft of the engine to the starting speed. As soon as the engine starts, the flywheel ring will begin to rotate the pinion faster than the starter shaft rotates, and it, having disengaged from the flywheel ring, will move along the helical splines of the shaft to its original position.
A high current is required to start the motor, so as part of maintenance it is necessary to ensure that the wire connections are in perfect condition. Clean rusty connections and treat with protective pole grease.
Note: Depending on the type, the starter is an exchangeable unit. This means that a faulty starter can be accepted by the manufacturer as partial payment for the purchase of a repaired or new starter. Therefore, when buying, you must have the faulty starter with you.
(The original article is located on: «BMWman.ru»)