TM 9--2815--247--34
0004 00--13
THEORY OF OPERATION -- CONTINUED
0004 00
TRANSMITTERS AND SWITCHES
Oil Pressure Gage Transmitter The electrical oil pressure gage transmitter is located at the right side of the
crankcase damper and oil filter housing on an adapter with the low oil pressure switch (Figure 1--2). This sealed
transmitter consists of a threaded plate to which a diaphragm, a radially--notched spring, and an overload guard
plate are crimped. Electrical resistance in the transmitter varies directly as the oil pressure varies. The resulting
variation in the current is transmitted to the electrical oil gage on the vehicle instrument panel.
Low Oil Pressure Warning Light Switch The low oil pressure warning light switch is furnished with the engine
and is located at the RH side of the crankshaft damper and oil filter housing (Figure 1--2). The electrical contact
points in this switch close when the oil pressure in the main oil gallery is below 11 ± 2 psi
(75.8 + 13.8 kpa). Completion of the electrical circuit lights the low pressure warning lamp on the vehicle instru-
ment panel.
Oil Temperature Transmitter The oil temperature gage transmitter is located on the lower RH side of the crank-
shaft damper and oil filter housing.
High Engine Oil Temperature Warning Light Switch The oil temperature warning light switch is located at the
upper RH side of the crankshaft damper and oil filter housing above the oil regulator valve. The warning light send-
ing switch thermostatically controlled electrical contact points close when oil temperature in the engine main oil
passage reaches 245 ± 5°F (118 + 15°C). Completion of the electrical circuit lights the oil high temperature warn-
ing lamp on the vehicle instrument panel.
SMOKE GENERATING SYSTEM
The smoke generating system uses the engine fuel pump to supply diesel fuel, from the vehicle fuel tanks, through
a manual fuel shutoff valve, to a solenoid valve mounted at the front of the engine. When the solenoid valve is en-
ergized (open), diesel fuel is sprayed into the engine exhaust system. The fuel vaporizes and together with the
engine exhaust gases, cools on contact with the ambient air and condenses to form a dense, homogeneous smoke
screen. The electrical power to energize the solenoid valve is applied via an ON/OFF switch activated by the ve-
hicle driver. The system is electrically enabled only when the engine is running to prevent accidental activation of
the smoke generating system when the engine is not running.
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