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 HYDRAMECHANICAL PROTECTIVE SYSTEM
SYSTEMS OPERATION
SCHEMATIC NO. 14 (LOW ENGINE OIL PRESSURE FAULT)'
(Low Speed Range)
1. Selector valve. 2. Low speed oil protection valve. 3. Start-up override valve. 4. Diverter valve orifice. 6.
Speed sensing valve spool. 7. Diverter valve. 8. Fuel shutoff actuator. 10. High speed oil protection valve. 15.
Fuel shutoff sequence valve. 17. Oil pump. 19. Remote normal shutoff valve.
As the crankshaft rpm becomes slower, the
LOW SPEED RANGE (LOW ENGINE OIL
governor feels the speed reduction and moves the
PRESSURE FAULT)
terminal shaft and linkage in the fuel "ON" direction,
against fuel shutoff actuator (8).
This moves the
Make Reference to Schematic No. 14
protective system oil back toward the system oil pump.
The check valves in diverter valve (7) move to stop this
If the engine oil pressure goes below 140 kPa
oil flow and keep the engine from surging.
(20 psi), the spring force on low speed oil protection
valve (2) will close the valve. The oil flow in the circuit is
NOTE: The start-up override valve (3) must be operated
then stopped and can not flow to drain. The pressure of
to release the fuel shutoff actuator hydraulic pressure
the oil will become equal on both sides of diverter valve
before the engine can be started.
orifice (4). Spring force will move the valve spool of
diverter valve (7) down so that there is alignment with the
passage that leads to fuel shutoff actuator (8). Oil
pressure will now move the fuel shutoff actuator which
will cause the governor to move the fuel control linkage
to the "SHUTOFF" position and shutdown the engine.
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