All motors require two magnetic fields, one produced by the stationary partof the motor (the stator, or field), and one by the rotating part (the rotor,or armature). These are produced either by a winding of coils carrying acurrent, or by permanent magnets. Car starter motors do not generally usepermanent magnets (although some do).
Car starter motors use a small device called an overrunning clutch, or one-way clutch. When you turn the ignition key to the run position, the starter solenoid interlocks the starter's pinion gear with the flywheel on the engine to rotate the engine at "cranking speed". Once the engine starts and exceeds cranking speed, the overrunning clutch releases the pinion gear from the flywheel.
However, if the solenoid mechanism is too worn to engage the flywheel, all you'll hear is a swishing sound as the armature in the starter spins all by itself, unable to crank the engine to a start. So this sound may indicate that the solenoid in the starter is worn out.
We can supply, repair and exchange car starter motors not only for those fitted on vehicles from European manufacturers but also more specialised markets including Asian, Japanese and American vehicles.
We have our own workshops for remanufacturing and repairing car starter motors and this enables us to provide an excellent technical backup and support service.