TM-9-2815-200-35 Maintenance Manual for AVDS-1790-2M AVDS-1790-2A and AVDS-1790-2AM Engines Download
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f. The engine crankcase is vented by an en- closed crankcase breather system which is vented through the crankcase breather tube (fig. 1-7) at the left turbosupercharger exhaust pipe. g. The engine primary and secondary fuel filters (fig. 1-3) have individual drain lines, with drain cocks, which provide a means of draining the filters to remove water which may be ac- cumulated and to purge the fuel system. Late production AVDS-1790-2A engines have a filter / water separator type secondary filter and drain lines to remove entrained moisture from the fuel (fig. 1-6). 1-9. Accessories Refer to paragraph 1-2 for information on engine accessories. 1-10. The crankcase (fig. l-l) is a one-piece Figure 1-8. Legend A - Intake valve rocker arm assembly B - Exhaust valve rocker arm assembly C - Left camshaft assembly D - Camshaft driven gear E - Camshaft drive gearshaft F - Camshaft drive shaft G - Camshaft drive bevel gearshaft H - Accessory drive gearshaft assembly J - Fuel injector pump advance assembly K - Right camshaft assembly L - Transmission accessory drive gearshaft M - Accessory drive gear N - Flywheel P - Generator drive gearshaft Q - Generator idler gear R - Oil pump driven gear S - Piston cooling oil pump driven impeller T - Pressure oil pump driven impeller U - Scavenge oil pump driven impeller V - Oil pump driven shaft W - Scavenge oil pump drive impeller X - Scavenge oil pump driven impeller shaft aluminum casting with forged aluminum main bearing caps. The bearing caps function as an integral part of the crankcase. Each cap is secured on studs with four slotted nuts. Two through bolts clamp the main bearing cap in the tunnel slot of the crankcase. With this type of crankcase and bearing cap construction, uniform load distribution in the bearing area is obtained making possible uniform distribution of com- bustion forces over the entire crankcase. 1-11. Main Bearings The seven replaceable main bearings are the steel-backed, split type, having copper-lead alloy bearing surfaces. The center main bearing is double-flanged with bearing material to control crankshaft end play and thrust. Y - Pressure oil pump drive impeller Z - Piston cooling oil pump drive impeller AA - Oil pump drive gear BB - Starter idler gear CC - Starter driven gearshaft DD - Starter drive gear EE - Front fan drive shaft FF - Fan drive bevel gearshaft GG - Rear fan drive shaft HH - Fan driven gearshaft JJ - Fuel injector pump drive gear shaft KK - Fuel injector pump driven shaft gear LL - Fan drive clutch assembly MM - Cooling fan adapter NN - Rear cooling fan assembly PP - Fan drive bevel gearshaft QQ - Crankshaft assembly RR - Fuel pump drive coupling SS - Fuel pump drive adapter TT - Crankshaft torsional vibration damper UU - Connecting rod assembly VV - Piston WW - Front cooling fan assembly XX - Exhaust valve YY - Intake valve 1-4