TM-9-2815-200-35 Maintenance Manual for AVDS-1790-2M AVDS-1790-2A and AVDS-1790-2AM Engines Download
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c. Oil Pump. The oil pump assembly consists of three sections combined as a single unit. The twin scavenge oil pump section of the unit picks up oil from the front and rear compartments of the oil pan and delivers it to the main pressure pump oil compartment. The main pressure oil pump section picks up oil from its respective compartment and supplies oil to the engine oil galleries and bearings. The piston cooling oil pump section picks up oil from the rear sump section of the oil pan and supplies oil to the piston oil sprayer nozzles (a, above). d. Oil Filters and Control Valves. The main and auxiliary oil filters (figs. 1-3 and 1-6) and the bypass valves are located in the crankshaft damper and oil filter housing at the front of the engine. All engine oil passes through a screen type main oil filter. Engine oil, which lubricates the fuel injection pump and the two tur- bosuperchargers (figs. 1-1, 1-2, and 1-4), is further filtered by a replaceable element type auxiliary oil filter. Two oil filter bypass valves are used, one for the main oil filter and one for the auxiliary oil filter. The main oil filter bypass valve opens at a differential pressure of 35.6 psi and the auxiliary oil filter bypass valve at a differential pressure of 15 psi. The bypass valves permit oil to bypass the filters in the event that they become clogged. 1-18. Fuel System a. Fuel Supply Pump Assembly. The engine driven vane type fuel supply pump assembly (figs. 1-3 and 1-6) is used to supply fuel under pressure to the fuel injection pump. The fuel pump is crankshaft driven by the fuel pump drive adapter (SS, fig. 1-8) and the drive coupling (RR ) located at the front of the engine. b. Fuel Injection Metering Pump. The fuel in- jection metering pump is located in the “V” of the engine between the fan drive housings, and supplies fuel under high pressure to each cylinder. The pump is driven at engine speed from the fan drive housing located at the rear of the engine. A fuel injector pump advance assembly (J, fig. 1-8) is incorporated in the accessory drive housing to automatically provide a gradual degree advance of injection timing during the engine speed range from idle to 1800 rpm. c. Fuel Injector Nozzles and Tubes. Twelve fuel injector nozzles (fig. 1-11), one per cylinder, are used to inject fuel into the combustion chambers, Twelve fuel injector tubes of equal length carry the fuel from the fuel injection pump to the nozzles. The nozzles on each cylinder bank are interconnected by fuel return lines to provide a path for the return of excess fuel. d. Fuel Purge System. A manually operated purge pump is provided in the vehicle operator’s compartment and is used to clear the engine main fuel system and flame heater system of air, and fill them with fuel. Purged air is forced through the main fuel tubes into the fuel return lines and on to the vehicle fuel tanks. The fuel filters contain drain lines, with manually operated valves, which are used to drain the water from the filters, and for purging the fuel system. 1-12