ROBERT BOSCH MODEL MW INJECTION PUMP - CONT

ROBERT BOSCH MODEL MW INJECTION PUMP - CONT - TM-5-3820-256-24-5_346

ROBERT BOSCH MODEL MW INJECTION PUMP - CONT - TM-5-3820-256-24-5_348

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 ROBERT BOSCH MODEL MW INJECTION PUMP Section 11 Mounting Adapter A mounting adapter incorporating four studs attaches to the injection pump housing. Capscrews through the injection pump drive gear cover secure the mounting adapter to the engine front plate. Removal of the timing pointer plug in the adapter is necessary when verifying or adjusting pump to engine timing. The mounting adapter is an integral part of the injection pump because it contains the timing pointer. During injection pump calibration, a port closure mark is stamped on the injection pump hub directly in line with the pointer. Because the timing pointer is located on the mounting adapter and the mounting adapter is fastened to the injection pump housing by the four studs and nuts, these four nuts should not be loosened. Loosening the nuts and rotating the pump housing in relationship to the mounting adapter will change the relationship of the timing pointer/hub mark which was established during injection pump calibration. MW Injection Pump Within the MW injection pump housing are the individual barrels and plungers, roller tappets and activating camshaft. Each barrel and plunger assembly is connected with the control rack to allow simultaneous changes of fuel delivery. A notch in the end of the pump camshaft drives the tachometer adapter. Fuel is drawn from the vehicle fuel tank through the primary and final fuel filters by the supply pump. Supply Pump with Hand Priming Pump The piston-type supply pump is activated by the eccentric on the injection pump camshaft and serves as a mount for the hand priming pump. Since all fuel entering the injection pump must be filtered to ensure long pump life, the hand priming pump should be used when changing fuel filters. Always install the fuel filters "dry" and use the hand pump to fill the filters and bleed air from the fuel system. RQV and RSV Governors A variable speed governor known as the "RQV" is used on truck engines. RSV variable speed governors are used on agricultural and construction equipment engines. RQV governors are used on truck engines because control lever forces are much lower and do not stress the driver’s foot. Aneroid Assembly Exhaust smoke levels during engine acceleration are controlled by using an aneroid. The aneroid limits fuel delivery during acceleration until the turbocharger speed is sufficient to provide adequate air for complete combustion. An external line connects the intake manifold to the aneroid to allow manifold pressure to activate the aneroid. A leak in the aneroid diaphragm or intake manifold to aneroid line will cause the injection pump to stay in the "cutback" position and reduce engine power. Fuel Return Valve A fuel return check valve is mounted to the injection pump housing and all fuel that is not injected passes through the check valve and then through a special orificed rubber hose. The function of the fuel return check valve is to provide a positive seal to prevent fuel from draining out of the pump housing when the engine is stopped. The fuel return check valve opens at approximately 18 psi. Therefore, total fuel flow through the injection pump housing is controlled by the orifice in the rubber hose as long as the supply pump pressure is above 18 psi. After the fuel flows through the orifice, the fuel pressure drops from the intermediate pressure ahead of the orifice to low pressure. CGES-185-3 PRINTED IN UNITED STATES OF AMERICA Page 3

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