TM 5-3895-346-14
STARTING MOTOR
ENGINE OVERHAUL
STARTING MOTOR
The starting motor is mounted on the flywheel housing as illustrated in Fig. 1. When the starting circuit is
closed, a small drive pinion on the armature shaft engages with the teeth on the engine flywheel ring gear to
crank the engine. When the engine starts, it is necessary to disengage the drive pinion to prevent the armature
from over speeding and damaging the starting motor. To accomplish this, the starting motor is equipped with a
Sprag-type overrunning clutch.
A solenoid switch, mounted on the starting motor
housing, operates the Sprag-type overrunning clutch
drive by linkage and a shift lever (Fig 2).
When the starting switch is engaged, the solenoid is
eneirgi2ed and shifts the starting motor pinion into
mesh with the: flywheel 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 overrules, or turns faster than
the armature, which permits the pinion to disengage
itself from the flywheel ring gear.
The solenoid plunger and shift lever is totally enclosed
Figure 1. Starting Motor Mounting
to protect them from dirt, water, and other foreign
material.
The nose housing an the Sprag clutch-type starting motor can be rotated to obtain a number of different
solenoid positions with respect to the mounting flange. When repositioning of the solenoid is required on a
service replacement starting motor, proceed as follows:
Starter with Intermediate-Duty Clutch (In-Line Engines)
The lever housing and the commutator end frame are held to the field frame by bolts extending from the end
frame
Figure 2 . Cross-Section of Motor with Intermediate-Duty Clutch
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