Figure 8. Exploded View of Fuel Injection Nozzle and Holder Assembly

Figure 7. Cut-Away View of Governor Assembly

TM-5-3820-256-24-5 Drilling System Well Rotary Truck Mounted Air Transportable 600 Feet Capacity Model LP-12 NSN 3820-01-246-4276 Manual
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SERVICE MANUAL GENERAL Section 1 The functions of the governor are: (1) limit minimum (lo-idle) engine speed, (2) limit maximum engine speed and (3) maintain smooth speed control (without stalling, surging or hunting) within the limits of its regulation throughout the operating speed range of the engine. The all-speed governor provides speed control at any fixed position of the control lever (accelerator pedal). This provides the vehicle operator with the most satisfactory driving characteristics. The governor tends to keep engine speed constant at the level determined by position of the accelerator pedal and automatically increases or reduces fuel delivery in response to minute changes in engine speeds without a significant change in road speed and without the operator changing position of the accelerator pedal. The transfer pump, a single action none positive displacement plunger type pump, is driven by the injection pump camshaft. The transfer pump can supply more fuel than is required for injection. Excess fuel, utilized for cooling injection pump, is routed from the injection pump fuel gallery back to the fuel pump. NOZZLE The American Bosch ADB-M type nozzles (Figure 8) are of the closed differential hydraulically-operated type. Fuel, under high pressure, flows into the fuel duct in the body and enters the pressure chamber. When fuel pressure in the pressure chamber exerts sufficient force on the differential area of the nozzle valve to overcome the opposing spring preload, the nozzle valve is lifted, allowing fuel to enter the nozzle body sac and flow through the spray holes. The fuel flowing through the spray holes is atomized as it enters the combustion chamber. When the end of the pumping stroke occurs, there is a sudden drop in line pressure. As a result, the pressure in the nozzle pressure chamber drops rapidly. Since the pressure adjusting spring is exerting a downward force on the nozzle valve and is no longer being opposed by fuel pressure, the nozzle valve moves downward rapidly until it seats in the nozzle body - the nozzle is now closed. Since there is a slight amount of clearance (controlled) between the nozzle valve and body, a small amount of leakage between the valve and body will occur. This leakage is necessary for valve O.D. and body I.D. lubrication. NOZZLE HOLDER The American Bosch AKN-M type nozzle holder (Figure 8) is a unit which retains the nozzle in the cylinder head and transfers the fuel from the high pressure tubing to the nozzle duct. The holder Figure 8. Exploded View of Fuel Injection Nozzle and Holder Assembly 1. Holder Body 5. Valve Stop Spacer 2. Shim(s) 6. Nozzle Body and Nozzle Valve 3. Pressure Adjusting Spring 7. Cap Nut 4. Spring Seat Guide 8. Copper Gasket CGES-375 Printed in United States of America Page 6

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