HYDRAMECHANICAL PROTECTIVE SYSTEM
SYSTEMS OPERATION
Air Inlet Shutoff The air inlet shutoff consists of a shutoff valve in the engine air inlet housing and a hydraulic actuator that holds the shutoff valve in the "OPEN" position. If an engine is operated in a combustible atmosphere, such as an oil or gas blow out on an oil rig, the air supply must be stopped to give a positive method of engine shutdown. If only the fuel control linkage was moved to the "SHUTOFF" position, the engine may continue to run on the air-oil-gas mixture pulled into the engine air intake.
SHUTOFF CONTROL GROUP 3. Shutoff control group. 4. Engine oil pressure line. 7. Diverter valve. 9. Oil line to thermostatic pilot valve. 10. Oil line to fuel shutoff actuator.
The hydramechanical protective system closes the air inlet shutoff valve to stop combustion air supply to the engine in an overspeed condition, to give a more positive shutdown. The air inlet shutoff valve is also closed when the emergency manual shutoff is operated. Since overspeed is a serious occurrence, the air inlet shutoff must be manually reset. This action requires a person t6 physically go to the engine and see if any damage has occurred. Fuel Shutoff Actuator This actuator is located on top of the Woodward UG-8 or the Caterpillar 3161 Governor. The actuator can be either an electric or hydraulic actuator that is operated any time the hydramechanical protective system causes engine shutdown. When operated by the diverter valve, the actuator moves the governor shutoff strap which causes the governor to move the engine fuel control linkage to the "SHUTOFF" position.
AIR INLET SHUTOFF 11. Air inlet shutoff housing. 12. Air inlet shutoff actuator. 13. Aftercooler housing.
COMPONENT LOCATIONS ON ENGINE
SHUTOFF CONTROL GROUP 1. Oil lines to air inlet shutoff actuator. 2. Rack sequence valve. 3. Shutoff control group. 4. Engine oil pressure line. 5. Emergency manual shutoff valve. 6. Cover (oil reservoir). 7. Diverter valve. 8. Air inlet sequence valve.
AIR INLET SHUTOFF 11. Air inlet shutoff housing. 13. Aftercooler housing. 14. Reset knob.
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