7.3
DETROIT DIESEL 53
STARTING MOTOR
The starting motor is mounted on the flywheel housing
When repositioning of the solenoid is required on a
as illustrated in Fig 1. When the starting circuit is
service replacement starting motor, proceed as follows:
closed, a small drive pinion on the armature shaft
Starter with Intermediate-Duty Clutch
engages with the teeth on the engine flywheel ring
(In-Line Engines)
gear to crank the engine. When the engine starts, it is
necessary to disengage the drive pinion to prevent the
The lever housing and the commutator end frame are
armature from overspeeding and damaging the
held to the field frame by bolts extending from the
starring motor. To accomplish this, the starting motor
end frame to threaded holes in the lever housing. The
is equipped with a Sprag-type overruning clutch.
nose housing is held to the lever housing by internal
attaching bolts extending from the lever housing to
A solenoid switch, mounted on the starting motor
threaded holes in the nose housing (Fig. 2). With this
housing, operates the Sprag-type overrunning clutch
arrangement, it is necessary to partially disassemble
drive by linkage and a shift lever (Figs. 2 and 3).
the motor to provide access to the nose housing
When the starting switch is engaged, the solenoid is
attaching bolts. Relocate the nose housing as follows:
energized and shifts the starting motor pinion into
mesh with the flywheel ring gear and closes the main
1. Remove the electrical connector and the screws
contacts within the solenoid. Once engaged, the clutch
attaching the solenoid assembly to the field frame.
will not disengage during intermittent engine firing.
Then remove the bolts from the commutator end
To protect the armature from excessive speed when
frame.
the engine starts, the clutch "overruns", or turns faster
than the armature, which permits the pinion to
2. Separate the field frame from the remaining
disengage itself from the flywheel ring gear.
assembly and pull the armature away from the lever
housing until the pinion stop rests against the clutch
pinion. This will provide access to the nose housing
The solenoid plunger and shift lever is totally enclosed
attaching bolts.
to protect them from dirt, water and other foreign
material.
3. Remove the nose housing attaching bolts with a box
wrench or open end wrench.
In the heavy-duty clutch type (Fig. 3), an oil seal,
between the shaft and the lever housing, and a linkage
4. Turn the nose housing to the required position.
seal prevents the entry of transmission oil into the
main frame of the starting motor and solenoid case,
NOTE: The solenoid must never be located
allowing the motor to be used on wet clutch
below the centerline of the starter or dust, oil,
applications.
moisture and foreign material can collect and
cause solenoid failures.
The nose housing on the Sprag clutch type starting
5. Reinstall the nose housing attaching bolts and
motor can be rotated to obtain a number of different
tighten them to 11-15 lb-ft torque.
solenoid positions with respect to the mounting flange.
6. Reassemble the motor.
Fig. 1 - Starting Motor Mounting
November, 1973
SEC. 7.3 Page 1
