3. Verify that the following items are not functioning:
electrical components, hour meter and engine
cranking. If any of the items continue to function
with the battery disconnect switch in the OFF
position, consult your Caterpillar dealer.
i01927889
Engine Shutoffs and Engine
Alarms
SMCS Code: 1900; 7400; 7418
Shutoff and Alarm Systems
Shutoffs and alarms are electrically operated or
mechanically operated. The operation of all electric
shutoffs and alarms utilize components which
actuate switches in a sensing unit.
Shutoffs are set at more critical levels for the
operating temperature, operating pressure, operating
coolant level, and operating speed (rpm) than the
alarms. The particular shutoff may need to be reset
before the engine will start.
NOTICE
Always determine the cause of the engine shutdown.
Make necessary repairs before attempting to restart
the engine.
Be familiar with the following items:
• Types and locations of shutoff
• Conditions which cause each shutoff to function
• The resetting procedure that is required to restart
the engine
Alarm switches consist of a sensor and a contactor.
Examples of sensors are the magnetic pickup for
detecting speed, and the pressure and temperature
sensors. Sensors are wired to contactors. The
contactors activate alarm circuits in the annunciator
panel.
Alarm switches are set at less critical levels than the
shutoffs. The alarms warn the operator that an
unsafe operating condition is occurring. The engine
will continue to run when an alarm sounds.
When an alarm is activated, corrective measures
must be taken before the situation becomes an
emergency in order to avoid possible engine
damage. If corrective measures are not taken within
a reasonable time, engine damage could result.
Alternatively, a corresponding shutdown device (if
equipped) will stop the engine. The alarm will
continue until the condition is corrected or the alarm
is reset by the operator.
A switch may be installed in the alarm circuit for
silencing the alarm while the engine is stopped for
repairs. Before starting, be sure that the switch is
moved to the closed ON. Be sure that the warning
lamps will operate. The engine will not be protected if
the switch is left in the open OFF position.
NOTICE
Always determine the cause of the engine shutdown.
Make necessary repairs before attempting to restart
the engine.
Air Shutoff Solenoid (If Equipped)
This optional solenoid is located on top of the engine.
The air shutoff is part of the air inlet system. When
the solenoid is activated, the solenoid mechanically
shuts off the inlet air to the engine. The solenoid can
be activated only by the overspeed switch or by the
emergency stop push button (ESPB). The air shutoff
must be reset before the engine is restarted.
Fuel Shutoff Solenoid
The fuel shutoff solenoid is located on the governor
or the fuel shutoff solenoid is located on the fuel
injection pump. When the fuel shutoff solenoid is
activated, the solenoid moves the fuel rack “OFF” .
The fuel shutoff solenoid moves the fuel rack directly
or the fuel shutoff solenoid moves the fuel rack
through the governor.
Mechanical Oil Pressure and Water
Temperature Shutoff
Illustration 77 g01009004
(1) Water temperature sensing valve
(2) Oil pressure sensing valve
(3) Shutdown cylinder
(4) Shutdown cylinder knob
70
SEBU7125-13
Operation Section
Engine Shutoffs and Engine Alarms
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