Shutoff and Alarm
Emergency Shutoff Controls
To silence the bell or horn while repairs are being made,
a two-way switch and a red indicator light may be
Emergency shutoff controls may be electrically,
installed. The red indicator light will come on when the
mechanically or hydraulically operated.
alarm is turned off.
yourself with the types and locations of the shutoff
controls, the conditions which cause each control to
The red light will stay on, to indicate that the engine is not
function, and the resetting procedure required to start
protected, if the switch is left in the OFF position after the
repairs have been made.
The operation of all electrical shutoff controls is similar.
A critical operating condition actuates a switch to stop
the engine. The shutoff control may require resetting
before the engine can start.
All alarms on the engine should be tested twice a year
for proper operation by referring to the Service Manual or
The shutoff controls should be tested every 1000 hours
authorized Caterpillar dealer personnel.
by authorized Caterpillar dealer personnel. Every 500
hours, the Hydra-Mechanical Shutoff can be tested
remotely by engine personnel.
During testing abnormal operating conditions must be
Do not use an emergency shutoff control for a normal
Perform the tests correctly to prevent
possible damage to the engine.
Always determine the cause of the shutdown, and have
the necessary repairs made before restarting the engine.
See the "Troubleshooting" section of this guide.
Alarm switches are set at a less critical temperature,
pressure, or level limit than the shutoff controls. The
purpose of the alarm switch is to warn the operator that
an unsafe operating condition is starting to occur.
Corrective measures must be taken to avoid possible
damage to the engine.
When an alarm is activated, corrective measures must
be taken before the situation becomes an emergency.
This low oil pressure switch is used in the oil system to
Each alarm switch is electrically connected to an
shut the engines down when oil pressure drops below
indicator light, bell or horn. The alarm will continue until
the condition is corrected. Then the light will turn off and
the bell or horn will be silenced.