DETROIT DIESEL 53
7.3
STARTING MOTOR
The starting motor (Fig. 1) has a shift lever and solenoid
plunger that are totally enclosed to protect them from
dirt.
The starting motor is equipped with a Sprag overrunning
clutch drive (Figs. 2 and 3). An important feature of the
Sprag type drive is that once the solenoid has moved
the starter pinion in mesh with the ring gear on the
flywheel, it will not disengage during intermittent engine
firing, which prevents damage to the pinion and the ring
gear teeth. The pinion remains engaged until starting is
assured and the solenoid circuit is interrupted.
The solenoid switch, mounted on the starting motor
housing, operates the overrunning clutch drive by
Fig. 1 Typical Starting Motor Mounting
means of linkage and a shift lever. When the starting
switch is engaged, the solenoid is energized, shifting the
threaded holes in the nose housing (Fig. 2). With this
starting motor pinion in mesh with the engine flywheel
arrangement, it is necessary to partially disassemble the
ring gear and closing the main contacts within the
motor to provide access to the nose housing attaching
solenoid. Battery current is then directed to the motor
bolts. Relocate the nose housing as follows:
causing the armature to turn. Cranking torque is
transmitted by the Sprag clutch from the starting motor
1.
Remove the electrical connector and the screws
armature to the engine flywheel ring gear. To protect
attaching the solenoid assembly to the field frame; then,
the armature from excessive speed as the engine starts,
remove the bolts from the commutator end frame.
the clutch "overruns", or turns faster than the armature,
which permits the pinion to disengage.
2.
Separate the field frame from the remaining
assembly and pull the armature away from the lever
The Sprag overrunning clutch drive type starting motor
housing until the pinion stop rests against the clutch
is used with an engine flywheel ring gear which has
pinion; this will provide access to the nose housing
either no chamfer or a Bendix chamfer. It cannot be
attaching bolts.
used with a ring gear which has a Dyer chamfer. When
installing a service replacement starting motor, make
3.
Remove the nose housing attaching bolts with a
sure the correct flywheel ring gear is also used.
box wrench or open end wrench.
Under normal operating conditions, no maintenance will
4.
Turn the nose housing to the required position.
be required on the starting motor between engine
NOTE: The solenoid must never be located below
overhaul periods.
the centerline of the starter or dust, oil, moisture and
foreign material can collect and cause solenoid
Adjustable Nose Housing
failures.
The nose housing on the Sprag clutch type starting
motor can be rotated to obtain a number of different
5.
Reinstall the nose housing attaching bolts and
solenoid positions with respect to the mounting flange.
tighten them to 11-15 Ib-ft torque.
When repositioning of the solenoid is required on a
service replacement starting motor, proceed as follows:
6.
Reassemble the motor.
STARTER WITH HEAVY-DUTY CLUTCH
STARTER WITH INTERMEDIATE DUTY
The nose housing, on starters equipped with the heavy-
CLUTCH
duty clutch, is attached to the lever housing by six bolts
The lever housing and the commutator end frame are
located around the outside of the housing (Fig. 3).
held to the field frame by bolts extending from the end
Relocate the nose housing as follows:
frame to threaded holes in the lever housing. The nose
housing is held to the lever housing by internal attaching
1.
Remove the six socket head screws (1short and
bolts extending from the lever housing to
1971 General Motors Corp.
May, 1971
SEC. 7.3 Page 1
