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