HYDRAMECHANICAL PROTECTIVE SYSTEM
SCHEMATIC NO. 3 (LOW ENGINE OIL PRESSURE FAULT)
(Low Speed Range)
1. Selector valve. 2. Low speed oil protection 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.
LOW SPEED RANGE (LOW ENGINE OIL
Make Reference to Schematic No. 3
If the engine oil pressure goes below 140 kPa
(20 psi), the spring force on low speed oil protection
valve (2) will close the valve. The oil flow in the
circuit is then stopped and can not flow to drain.
The pressure of the oil will become equal to both
sides of diverter valve 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
activate the fuel shutoff actuator, which will cause
the governor to move the fuel control linkage to the
"SHUTOFF" position and shutdown the engine.