ARMY TM 9-6115-643-24
AIR FORCE TO 35C2-3-445-22
With the cranking relay energized, power passes from the batteries through closed contacts of the cranking relay to ener-
gize the starter solenoid. With the starter solenoid energized, power passes from the starter solenoid to the cranking mo-
tor. The cranking rnotor then cranks the engine. Engine speed is sensed by the magnetic pickup which sends a signal to the
electronic governor control. As the engine accelerates to approximately 900 rpm, the signal from the magnetic pickup
causes the crank disconnect switch to open one set of contacts and close another set of contacts. The open contacts break
the circuit to the cranking relay and stop engine cranking. The closed contacts cause the field flash relay to be energized.
When the MASTER SWITCH is moved to one of the two RUN positions, both starting control circuits are deenergized. The
other generator set control and instrument circuits remain energized.
The engine may be cranked without starting by use of the DEAD CRANK switch, With the DEAD CRANK
switch in the CRANK position, the cranking relay coil is energized to initiate engine cranking without energizing any other
starting or control functions.
The generator set can be started without batteries by connecting an external 24 VDC power source to the
NATO SLAVE RECEPTACLE. The generator set can also supply starting power to another set through the NATO SLAVE
The batteries are charged by the battery charging alternator that is belt driven by the engine. The BATTERY
CHARGE ammeter indicates the charge/discharge rate of the batteries, from -10 Amps to +20 Amps. A shunt provides
a DC voltage signal, which is directly proportional to the actual battery current flow, to the BATTERY CHARGE ammeter.
Normal operating indication on the BATTERY CHARGE ammeter depends on the state of the charge in the batteries. A
low charge, which may exist immediately after engine starting, will cause a high reading (needle moves toward CHARGE
area). When the charge in the batteries has been restored, the indicator moves near zero (0). The battery charging system
is protected from reverse polarity in the battery connections by a fuse and diode.
Field Flash. When the engine reaches sufficient speed (900 rpm), the magnetic pickup causes a set of con-
tacts in the crank disconnect switch to close and energize the field flash relay. This circuit provides current to the exciter
field windings which sets up an electromagnetic field. The field current is necessary for the set to generate sufficient volt-
age for the voltage regulator (FIGURE 1-11) to begin controlling the output voltage oft he generator set. The field flash
circuit is maintained until the MASTER SWITCH is released from the START position.
Operation. Placing the MASTER SWITCH in the PRIME& RUN or PRIME & RUN AUX FUEL positions keeps
the electronic governor control (FIGURE 1-10) energized, and fuel will be supplied to the fuel injection pump as long as
no fault condition exists. During operation, the operator should periodically check the sets instruments to ensure they are
reading in the normal operating ranges. The VOLTAGE and FREQUENCY potentiometers are adjusted as required to
maintain desired frequency and voltage output.