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 HYDRAMECHANICAL PROTECTIVE SYSTEM
SYSTEMS OPERATION
SCHEMATIC NO. 11 (START-UP OVERRIDE)
2. Low speed oil protection valve. 3. Start-up override valve. 4. Diverter valve orifice. 7. Diverter valve. 8.
Fuel shutoff actuator. 15. Fuel shutoff sequence valve.
START-UP OVERRIDE OF LOW ENGINE OIL
PRESSURE
Make Reference to Schematic No. 11
On a hot restart, after severe operating
conditions, the engine oil pressure can increase
slowly. If the rate of pressure increase is too
slow, the protective system activates fuel shutoff
actuator (8) to move the fuel control linkage to
the "SHUTOFF" position be- cause of a low
engine oil pressure fault condition. Therefore, an
override of the engine oil pressure circuit is
needed in the protective system.
An electric solenoid or air operated start-up over-
ride valve (3) is installed in the diverter valve
return line. The valve is normally closed. When
start-up override valve (3) is operated, the outlet
of the diverter valve is connected to drain. This
maintains a pressure drop across diverter valve
orifice (4) and does not let the diverter valve shift
to the shutdown position.
When start-up override valve (3) is not in use,
the engine oil circuit is put back into normal
operation as in Schematics No. 2 and No. 4.
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