TM 5-3895-379-23
THEORY OF OPERATION - CONTINUED
0003 00
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 harnesses. There are four wiring harnesses on the roller: the instrument, engine, and front and rear har-
nesses. Electricity is sent through the harnesses to the electrical systems then 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 to 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 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.
Battery Cables. The positive battery cable is connected to the NATO connector and the starter. The negative cable is
3.
connected to the battery disconnect switch which is then connected to the roller chassis.
NATO Connector. The NATO connector is a standard receptacle with which NATO jumper cables can be used to "jump
4.
start" one roller by another roller in the event of battery failure.
5.
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 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 cur-
rent by a three-phase, full wave rectifier system. Direct current flows to the alternator output terminal. The rectifier
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, alterna-
tor excitation occurs when the engine start switch is turned on.
Alternator Circuit Breaker. The alternator circuit breaker is a heat-triggered switch that opens the battery circuit when
6.
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 00-8
