5-2
ELECTRIC STARTER SYSTEM
GENERAL
The starter is made up of an armature, field winding assem-
bly, solenoid, drive assembly, idler gear and drive housing.
The starter motor torque is increased through gear reduction.
The gear reduction consists of the drive pinion on the arma-
ture, an idler gear and a clutch gear in the drive housing. The
idler gear is supported by rollers. The clutch gear is part of
the overrunning clutch/drive assembly.
The overrunning clutch is the part which engages and drives
the clutch ring gear. It also prevents the starter from overrun-
ning. The field windings are connected in series with the
armature through brushes and commutator segments.
Wiring Diagrams
For additional information concerning the starting system cir-
cuit, see the wiring diagram at the end of Section 7, ELEC-
TRICAL.
Starter Relay
The starter relay is a non-repairable part that must be
replaced as a unit if it fails.
OPERATION
See Figure 5-1. The starter relay is activated when the starter
switch is pushed. This allows battery current to flow into the
pull-in winding and also into the hold-in winding to ground. The
magnetic forces of the pull-in and hold-in windings in the sole-
noid push the plunger causing it to shift to the left. This action
engages the pinion gear with the clutch ring gear. At the same
time, the main solenoid contacts are closed, so battery current
flows directly through the field windings to the armature and to
ground. Simultaneously, the pull-in winding is shorted. The cur-
rent continues flowing through the hold-in winding keeping the
main solenoid contacts closed. At this point, the starter begins
to crank the engine. After the engine has started, the pinion
gear turns freely on the pinion shaft through the action of the
overrunning clutch. The overrunning clutch prevents the clutch
ring gear (which is now rotating under power from the engine)
from turning the armature too fast.
When the starter switch is released, the current of the hold-in
winding is fed through the main solenoid contacts and the
direction of the current in the pull-in winding is reversed. The
solenoid plunger is returned to its original position by the
return spring, which causes the pinion gear to disengage
from the clutch ring gear.
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