HIGH ENGINE COOLANT TEMPERATURE CIRCUIT (FAULT CONDITION)

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SCHEMATIC NO. 6 (ENGINE COOLANT TEMPERATURE CIRCUIT) (Low Speed Range Shown)

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TM-5-2815-232-14 Engine Diesel Caterpillar Model 3508 Manual

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OVERSPEED CIRCUIT (NORMAL CONDITIONS)

HYDRAMECHANICAL PROTECTIVE SYSTEM

SYSTEMS OPERATION

SCHEMATIC NO. 7 (HIGH ENGINE COOLANT TEMPERATURE FAULT)

1. Selector valve. 2. Low speed oil protection valve. 4. Diverter valve orifice. 7. Diverter valve. 8. Fuel shutoff

actuator. 9. Thermostatic pilot valve. 10. High speed oil protection valve. 15. Fuel shutoff sequence valve.

HIGH ENGINE COOLANT TEMPERATURE

CIRCUIT (FAULT CONDITION)

Make Reference to Schematic No. 7

When engine coolant temperature increases to

99C (2100F), thermostatic pilot valve (9) will

open. This will let engine oil in the circuit drain

and cause a decrease in oil pressure on low

speed oil protection valve (2) and high speed oil

protection valve (10). Valves (2) and (10) will

close and stop oil flow from diverter valve (7).

The difference in oil pressure across diverter

valve orifice (4) will now go to zero. The valve

spool of diverter valve (7) will move down by

spring force, which will cause alignment of the

ports to fuel shutoff actuator (8). The actuator

now causes the governor to move the fuel

control linkage to the "SHUTOFF" position and

shutdown the engine.

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