Engine Equipment
DETROIT DIESEL
ALARM SYSTEM
The alarm system shown in Fig. 5 is similar to the
automatic electrical shut-down system, but uses a
warning bell in place of the air shut-off valve solenoid.
The bell warns the engine operator if the engine
coolant overheats or the oil pressure drops below the
safe operating limit.
When the engine is started and the oil pressure is
sufficient to open the oil pressure switch contacts
(opening pressure is stamped on the switch cover), the
alarm switch must be turned on manually to put the
system in operation. The water temperature switch is
normally open. Should the engine coolant exceed
205 5 F (96 15 C), the water temperature
switch will close the electrical circuit and sound the
alarm bell. Likewise, if the oil pressure drops below
the setting of the oil pressure switch, the switch will
close and cause the bell to ring. The bell will continue
to ring until the engine operator turns the alarm
switch off. The alarm switch must also be turned off
before a routine stop since the decreasing oil pressure
will close the oil pressure switch and cause the bell to
ring.
If the alarm bell rings during engine operation, stop
the engine immediately and determine the cause of
Fig. 5 - Alarm System Wiring Diagram
the abnormal condition. Make the necessary corrections
before starting the engine again.
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