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
5F., 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 the
abnormal condition. Make the necessary corrections
before starting the engine again.
Fig. 5. Alarm System Wiring Diagram
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