SHUTOFF AND ALARM SYSTEMS
MECHANICAL OIL PRESSURE AND WATER
MECHANICAL SHUTOFF GROUP 1. 011 pressure
sensing valve. 2. Tee. 3. Water temperature sensing
valve. 4. Shutdown cylinder.
The shutdown cylinder (4) is mounted to the rear of the
governor housing. The plunger of the cylinder acts on a
housing. When extended, the plunger rotates the lever
assembly to allow full movement of the fuel rack. When
the plunger is retracted, the lever assembly returns to its
original position which moves and holds the fuel rack in
the shutoff position.
When starting the engine, the knob on shutdown cylinder
(4) must be held in to extend the plunger against the
lever assembly inside the governor housing. This will
full rack movement. After the engine starts and oil
pressure is high enough to hold the plunger extended,
the knob can be released. Oil pressure will hold the
plunger in this position until there is a low oil pressure
Under normal operating conditions, pressure oil from
the engine oil manifold flows to tee (2). Part of the oil
from the tee flows through water temperature sensing
valve (3) into the pressure inlet end of oil pressure
sensing valve (1) where the oil flow is blocked and the oil
pressure is monitored. The other part of the oil flow from
tee (2) flows to and through the drain end of valve (1) on
to shutdown cylinder(4) where the oil flow is blocked and
the pressure holds the cylinder plunger extended.
When the oil pressure gets too low the drain end of
valve (1) will open causing the pressure oil to cylinder (4)
to drain back to the engine block. With no oil pressure in
cylinder (4), the lever assembly in the governor returns to
its original position pushing the cylinder plunger to the
retracted position and moves the fuel rack to the shutoff
position to stop the engine.
When the water temperature is too high, the
pressure oil that flows through water temperature
sensing valve (3) is diverted to drain within the valve
body and flows back to the engine block.
This causes the oil pressure to become too low and the
engine will stop as described above.
Find and correct the problem that caused the engine
to stop. This will help prevent damage to the engine
from not enough lubrication or too much heat.