TM 5-3810-300-24&P-3
7.4
INSTRUMENT PANEL AND INSTRUMENTS
The instruments generally required in the operation of a
voltage. The small current registered prevents rapid
diesel engine consist of an oil pressure gage, water
brush wear in the battery-charging generator. If lights or
temperature gage, ammeter, and a mechanical
other electrical equipment is connected into the circuit,
tachometer. Instruments with slotted cases are available
then the ammeter will show discharge when these items
for use with lighted dashes. Also, closely related and
are operating and the engine speed is reduced.
usually installed in the general vicinity of these
instruments are certain controls consisting of an engine
Tachometer
starting switch, and engine stop. knob, and an
The tachometer, driven by the engine, registers the
emergency stop knob.
speed of the engine in revolutions per minute (rpm).
Oil Pressure Gage
Throttle Control
The oil pressure gage registers the pressure of the
lubricating oil in 'the engine. As soon as the engine is
The engine throttle is connected to the governor speed
started, the oil pressure gage should start to register. If
control shaft through linkage. Movement of the speed
the oil pressure gage does not register at least the
control shaft changes the speed setting of the governor
minimum pressure listed in the "Operating Conditions" in
and thus the engine speed.
Section 13.2, the engine should be stopped and the
cause of the low oil pressure determined and corrected
Engine Starting Switch
before the engine is started again.
To start the engine, a switch is used to energize the
starting motor. Starting switches may vary in design and
Water Temperature Gage
their contacts must be rated sufficiently to carry the
The engine coolant temperature in the water manifold is
registered on the water temperature gage.
Engine Stop Knob
Incorrect water temperature readings will be registered if
the gage assembly is incorrectly installed or the capillary
A stop knob is used to shut the engine down. When
tube is damaged.
stopping an engine, the engine speed should be reduced
to idle and the engine allowed to operate at idle for a few
To prevent damage to the gage assembly from vibration,
minutes, to permit the coolant to reduce the temperature
the capillary tube must be securely fastened to the
of the engine's moving parts. Then, the stop knob
engine the full length with suitable clips at intervals of 10
should be pulled and held until the engine stops. Pulling
inches or less. Sharp bends in the tube must be
on the stop knob manually places the injector racks in
avoided, particularly at the gage or bulb connection
the no-fuel position. The stop knob should be returned
areas. Where the tube must be bent around any object,
to its original position after the engine stops.
the bend must not be less than 1 inch radius.
Emergency Stop Knob
Any extra length can be taken up by coiling, the diameter
of which should not be less than two inches. The coils
In an emergency, or if the engine continues to operate
must be located so that they may be securely fastened to
after pulling the stop knob, the emergency stop knob
prevent vibrating.
may be used to stop the engine. When the emergency
stop knob is pulled, the air shutdown valve, located
between the air intake and the blower, will trip and shut
An ammeter is wired into the electrical circuit to show the
off the air supply to the engine. Shutting off the supply of
current flow to and from the battery. After starting the
air to the engine will prevent further combustion of the
engine, the ammeter should register a high charge rate
fuel and stop the engine.
at rated engine speed. This is the rate of charge
received by the battery replenishing the current used to
The emergency stop knob must be pushed back in after
start the engine. As the engine continues to operate, the
the engine is stopped, and the air shut-down valve must
ammeter should show a decline in the charge rate to the
be re-set manually. The cause of the malfunction should
battery. The ammeter will not show zero charge rate
be determined before the engine is started again.
since the regulator voltage is set higher than the battery
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