TM 5-3810-300-24&P-3
7.3
Sprag Overrunning Clutch Type Starting Motor
A solenoid switch, mounted on the starting motor
housing, operates the current sprag type overrunning
clutch drive by linkage and a shift lever (Fig. 2). When
the starting switch is engaged, the solenoid is energized
and shifts the starting motor pinion into mesh with the
flywheeel ring gear and closes the main contacts within
the solenoid.
Once engaged, the clutch will not
disengage during intermittent engine firing. To protect
the armature from excessive speed when the engine
starts, the clutch "overruns", or turns faster than the
armature, which permits the pinion to disengage itself
Fig. 1 - Sprag Overrunning Clutch Type Starting Motor
from the flywheel ring gear.
Mounting (Current)
The solenoid plunger and shift lever on this type of
The starting motor is mounted on the flywheel housing
starting motor is totally enclosed to protect them from
as illustrated in Fig. 1. When the starting circuit is
dirt, water and other foreign material.
closed, a small drive pinion on the armature shaft
engages with the teeth on the engine flywheel ring gear
An oil seal, between the shaft and the lever housing, and
to crank the engine. When the engine starts, it is
a linkage seal (Fig. 2) prevents the entry of transmission
necessary to disengage the drive pinion to prevent the
oil into the main frame of the starting motor and solenoid
armature from overspeeding and damaging the starting
case, allowing the motor to be used on wet clutch
motor.
To accomplish this, the starting motor is
applications.
equipped with a heavy-duty sprag overrunning clutch or a
Dyer drive.
The nose housing on the sprag clutch type starting motor
can be rotated to obtain a number of different solenoid
positions with respect to the mounting flange. The nose
housing, on starters equipped with the heavy-duty clutch,
is attached to the lever housing by
Fig. 2 - Cross-section of Starting Motor with Sprag Heavy-Duty Clutch Drive
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