TM 5-3895-379-23-1
0003
ELECTRICAL SYSTEM
1. General.
a. Two batteries wired in series provide the roller with a 24-volt electrical system. Battery cables
connect the batteries to the starter and the alternator. From the starter, electricity is sent to the
engine wiring harness and to the operator station. When the roller is running, the alternator produces
24 volts that are sent to the batteries to maintain a full charge. Control switches at the operator
station allow the flow of electricity to power the roller systems through the wiring harness. There are
four wiring harnesses on the roller: the instrument, engine, front, and rear harnesses. Electricity is
sent through the harnesses to the electrical systems the returned to the harness, which ground the
electricity to the roller chassis. Fuses are used to protect the electrical systems from an overload.
The negative battery cable is attached to the chassis, completing the circuit. A NATO connector on
the battery positive side allows the roller to be connected to another vehicle. This connector allows
another roller's electrical system be connected to the roller if, for example, the roller does not have
enough electrical energy to start the motor with its own batteries.
b. The starting system is used to start the engine. When the start switch is tuned to the START position,
electricity is sent from the battery to the fuses and then through the main relay, the neutral start relay
and the starter relay. The starter relay engages the starter solenoid. The starter solenoid sends
electricity to the electricity to the electric starter motor and forces it to turn the engine crankshaft.
The engine will crank until the start switch is turned to the center or OFF position.
2. Batteries. Two 12-volt batteries provide stored electricity to the electrical system. Combined, the two
batteries provide 24 volts. The batteries are negatively grounded.
3. Battery Cables. The positive battery cable is connected to the NATO connector and the starter. The
negative cable is connected to the battery disconnect switch which is then connected to the roller chassis.
4. NATO Connector. The NATO connector is a standard receptacle with which NATO jumper cables can be
used to "jump start" one roller in the event of battery failure.
5. Alternator.
a. The alternator is an electrical and mechanical component driven by a belt from engine rotation. The
alternator is used to charge the storage batteries during engine operation. The alternator is used to
charge the storage batteries during engine operation. The alternator is cooled by an external fan
mounted behind the pulley. The fan pulls air through holes in the back of the alternator and exits to
the front, cooling the alternator.
b. The alternator converts mechanical and magnetic energy to Alternating Current (AC) and voltage
by rotating a Direct Current (DC) field inside a three-phase stator. The alternating current and voltage
are changed to direct current by a three-phase, full wave rectifier system. Direct current flows to the
alternator output terminal. The rectifier has three exciter diodes that rectify the current needed to
start the charging process.
c.
A solid state regulator is installed in the back of the alternator. A capacitor protects the rectifier from
high voltages.
d. The alternator is connected to the battery through the engine start switch for alternator turn-on.
Therefore, alternator excitation occurs when the engine start switch is turned on.
6. Alternator Circuit Breaker. The alternator circuit breaker is a heat-triggered switch that opens the battery
circuit when the current in the electrical system goes higher than the rating of the circuit breaker (60 amps).
Push the reset button to close the circuit again.
0003-8
03/15/2011Rel(1.8)root(thrywp)wpno(G00006)
