Section Xll. MAINTENANCE OF ELECTRICAL SYSTEM

Figure 4-23. Timing marks on timing gear and governor drive gear.

Section Xll. MAINTENANCE OF ELECTRICAL SYSTEM

4-36. Description

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

instructions

may

damage

the

the engine is started and is restored by the battery

alternator rectifiers, voltage regulator,

charging system consisting of the alternator (1) and

and wiring.

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

CAUTION

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

disengage relay.

alternator and regulator.

Do not

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.

The

circuit

with

the

rotor

winding

terminals are molded onto the cables.

energized.

Do not ground the

f. The engine controls and instruments are

alternator output circuit. Take care to

prevent reversing polarity of the

4-39