9000 L4-1985cc 2.0L DOHC (1986)
Starter Motor: Description and Operation
Principle of Operation
Description
1
Pinion bracket assembly
2
Solenoid
3
Permanent magnets
4
Brush-holder assembly
5
Pinion-engaging lever
6
Planetary gearing
7
Rotor
8
Starter motor housing
The starter motor in the Saab 9000 is equipped with planetary gearing.
Compared with conventional types, this starter motor is lighter and more compact. It also runs at a higher speed.
Operation
The starter motor rotates the engine flywheel by means of a pinion which drives a ring gear. A solenoid moves the starter motor pinion axially into
engagement with the engine flywheel when the ignition switch is turned to the Start position. This actuates a switch which closes the circuit to the starter
motor.
When the engine starts the flywheel will rotate faster than the starter motor. This causes the free-wheel function to disengage the starter motor pinion
from its drive shaft and so prevent overrevving of the starter motor.
When the ignition switch is turned from the Start position to the Drive position, current to the solenoid is cut off and a spring returns the pinion to its rest
position.