Description And Operation - Ford VSG-411 Service Manual

05-3 Startina Svstem
05-3
DESCRIPTION AND OPERATION
There are two starters available in the VSG range. Most
engines are equipped with the Bosch electromagnetic field
starter which is detailed in this section. Some engines are
equipped with the United Technologies permanent magnet
starter. This starter features an inertially-actuated pinion
gear which is described later in this section.
The electromagnetic field starter is a four pole, four brush
motor with a series field and a solenoid-operated roller
clutch drive.
The solenoid assembly is mounted to a flange on the
starter drive housing. The entire shift lever mechanism and
the solenoid plunger are enclosed in the drive housing,
thus protecting them from exposure to dirt and road splash.
The solenoid incorporates two windings, a pull-in-winding
and a hold-in winding. Together they provide sufficient
magnetic attraction to pull the solenoid plunger into the
solenoid.
Engine cranking occurs when the starter solenoid on the
starter is energized through the starter control (ignition)
switch. When energized, the solenoid shifts the starting
motor pinion into mesh with the engine flywheel ring gear.
Simultaneously, the main contacts of the solenoid are
closed and battery current is directed to the starting motor
causing the armature to rotate.
After the engine starts,
the
starter drive is disengaged
when the ignition switch is returned from the start to the
ON or RUN position. This opens the circuit to the starter
solenoid and the solenoid return spring causes the shift
lever to disengage the starter drive from the engine
flywheel ring gear.
The starting motor is protected from excessive speed by
an overrunning clutch incorporated in the starter drive
assembly. The overrunning clutch permits the drive pinion
gear to rotate faster than the armature thus disengaging
itself from the engine flywheel ring gear when the engine
starts.