TROUBLESHOOTING THE M998 ELECT SYST. - OD1617 - LESSON 1/TASK 1
developed as automotive technology progressed.
The modern electric
starting system has reduced the task of starting an internal
combustion engine to the turn of a key or the pushing of a button.
The starter may drive the engine through a pinion, or by a dog clutch
attached to the starter armature shaft.
Operation of the starter
energizes a solenoid which brings the shaft together with the teeth
cut in the rim of the flywheel, or with the mating half of the dog
clutch. To avoid damage to the starter, the drive must be equipped
with
an
overrunning
clutch
or
some
other
means
of
quick
disengagement.
Owing to limitations of size and capacity of the
battery, a high-speed starter with a high gear reduction is used to
obtain the necessary torque.
The great speed reduction required is
usually effected by using the flywheel as a driven gear.
In some
instances, the gear is bolted or shrunk on the flywheel; in others,
as stated above, the gear teeth are cut directly in the rim of the
flywheel itself. The starter is mounted on the flywheel housing.
The starter used on the HMMWV is a 24 volt unit activated by the
RUN/START switch through a solenoid mounted on the starter motor
housing.
The switch is placed to the RUN position and the WAIT TO
START lamp illuminates. A relay in the protective control box (PCB)
energizes the glow plugs and, after approximately six seconds, the
WAIT TO START lamp will extinguish. The vehicle may now be started
by placing the switch to the START position. The starter will engage
the crank and thus start the engine. Releasing the switch allows it
to return to the RUN position. In other words, the switch is spring-
loaded to the RUN position. An AC output from the alternator to the
PCB prevents the starter from re-engaging once the engine is running.
A neutral (safety) switch mounted in the transmission quadrant
prevents the vehicle from being started in any gear other than
neutral (N).
(4) Wiring Design. The vehicle wiring design uses a harness-type
construction arranged to separate the harness into four major sub-
assemblies. These sub-assemblies are: engine, body, simplified test
equipment/internal combustion engine (STE/ICE), and hood.
The
harness sub-assemblies include multi-circuit disconnects, permitting
removal of the major assemblies for maintenance.
4
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