HYDRAMECHANICAL PROTECTIVE SYSTEM
TESTING AND ADJUSTMENT
system. Pull emergency manual shutoff
knob ( I). Successful shutdown of intake
air and fuel indicate correct operation.
After the emergency manual shutoff has been
operated, the air inlet shutoff valve must be opened.
Also, the start-up override must be operated to
release hydraulic pressure from the fuel shutoff
actuator before the engine can be started again.
Remove seal and wire from the bolts and
remove the cover from over the high idle
adjustment screw on the Caterpillar 3161
Governor, or the seal wire from high idle screw
3. High idle adjustment screw.
lock nut on Woodward UG-8L Governor.
clockwise. Again, slowly increase the
Connect a tachometer of known accuracy to the
engine rpm to check for engine
shutdown at 18% + 25 rpm above full
NOTE: Some types of engine driven equipment, such as
generators, pumps or compressors, can be damaged if
operated at 18% above full load speed. If so, the driven
equipment must be disconnected from the engine during
this test. If this cannot be done, adjustment of the
shutoff control group can be made on the
CATERPILLAR FUEL INJECTION TEST BENCH. See
Form No. SEHS7466 for the complete test bench
Start the engine again and operate it at high idle
with no load.
Turn the governor high idle adjustment screw
ADJUSTMENT OF HIGH IDLE ON 3161 GOVERNOR
slowly to increase engine rpm. The air inlet
shutoff must close and the fuel must be shut off
NOTE: If engine shutdown occurs before 18% + 25 rpm
through the governor and fuel control linkage at
of full load rpm, turn overspeed adjusting bolt (2)
18% + 25 rpm above full load rpm. For example,
clockwise to increase the shutoff control group
this is 2124 + 25 rpm for an engine rated at 1800
Repeat the above procedure until
shutdown occurs at the correct rpm.
After the hydramechanical protective system has
been activated, the air inlet shutoff valve must be
Adjust engine high idle to the specifications
Also, the start-up override must be
shown on the Engine Information Plate which is
operated to release hydraulic pressure from the fuel
attached to one of the right side camshaft
shutoff actuator before the engine can be started
inspection covers. If the Engine Information
Plate is missing, see the FUEL SETTING AND
RELATED INFORMATION FICHE for the correct
If engine shutdown does not occur at 18% + 25
specifications to use.
rpm above full load rpm, slowly increase engine
rpm 50 rpm more. For example, this is 2174
Install the seals and lockwires for the shutoff
rpm for an engine rated at 1800 rpm. If engine
control group and the governor high idle
shutdown still does not occur, decrease the
engine rpm and remove the seal and lockwire
and turn overspeed adjusting bolt (2) one turn