Figure 4-23. Timing marks on timing gear and governor drive gear.
Section Xll. MAINTENANCE OF ELECTRICAL SYSTEM
When using a
a. The electrical system includes two 12-volt, lead-
battery booster or fast charger, make
acid-type storage batteries connected in series to power
sure the leads are connected with
the 24-volt electrical system. Battery output is used to
proper polarity. Failure to follow these
energize the electrical starting motor (7, fig. 3-3) to start
the engine. The battery charge is partially depleted as
the engine is started and is restored by the battery
alternator rectifiers, voltage regulator,
charging system consisting of the alternator (1) and
voltage regulator (10).
c. Reverse polarity connections to an alternator can
The alternator and regulator are typical
severely damage the alternator.
To prevent this
automotive types in which the alternator output is
damage, the system is protected by a reverse polarity
controlled through the voltage regulator, depending
protector (9, fig. 3-3) which is mounted on the panel
upon the state of charge of the batteries. When the
next to the voltage regulator.
battery charge is low, the voltage regulator increases the
d. The engine starting motor (7, fig. 3-3) is a
strength of the alternator field to increase the output of
solenoid-operated type in which the solenoid switch (6)
the alternator. When the battery charge is normal, the
is mounted on top the starting motor. The solenoid
output of the alternator decreases to near zero.
switch uses electrical energy to pull the starting motor
drive into engagement with the fly-wheel ring gear and
Though this engine is equipped with a
to make the electrical circuit which energizes the
reverse polarity protector to protect
starting motor after the drive is engaged. When the
the alternator against damage due to
engine starts, the starting motor drive is disengaged,
reverse polarity connections, it is good
preventing the engine from driving the starting motor
practice to take special precautions
which could be severely damaged by engine operating
when connecting and disconnecting
speeds. Reengagement of the starting motor while the
electrical leads and cables. Do not
engine is running is prohibited by the starting motor
ground the field terminal between the
alternator and regulator.
e. The battery cables are automotive type, with a
operate the alternator in an open
large cross section of copper wires to transmit the heavy
current required when starting the engine.
terminals are molded onto the cables.
Do not ground the
f. The engine controls and instruments are
alternator output circuit. Take care to
prevent reversing polarity of the