NMWR-9-2815-220 Overhaul Manual for M60 M88 Engine AVDS-1790-2CA, AVDS-1790-2DA, AVDS-1790-2DR Download
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NMWR 9-2815-220 EQUIPMENT DESCRIPTION AND DATA—Continued 0002 00 LOCATION AND DESCRIPTION OF MAJOR COMPONENTS - CONTINUED (2) Models AVDS-1790-2DA and AVDS-1790-2DR Engine Generators. The Models AVDS-1790-2DA and AVDS-1790-2DR engines use a 28 volt air cooled dc generator capable of developing 300 ampere output. Cooling air is drawn from the crew compartment via an air intake tube by a blower mounted on the generator. The intake tube extends along the crankcase below the intake manifold on the right side of the engine. Exhaust air is conveyed from the generator by an air exhaust tube elbow connected to the rear of the engine shroud. Generator outlet air is exhausted through the engine’s rear cooling fan vane. e. Engine Starter. The engines are equipped with a 24 volt solenoid operated starter. A low voltage sensing module is included to prevent starter operation with improperly charged batteries. f. Engine Lubrication System. Engine lubrication is provided by a force feed system consisting of four circuits. These are the scavenge circuit, the main or pressure oil circuit, the leveling circuit, and the make up circuit. Each circuit is operated independently by a single oil pump consisting of four separate sections. g. Engine Crankcase Breather System. The engine crankcase is vented by an enclosed breather system which is vented through the crankcase breather tube at the left turbosupercharger exhaust pipe. h. Engine Manifold Heater System. The engines are equipped with two intake manifold heaters that are installed between the intake manifold elbows and the turbosuperchargers. The heaters, when operated, preheat air entering the cylinders to facilitate cold weather starting and idle operations. NOTE Smoke generating system will not produce smoke if the vehicle fuel is JP-8. i. Smoke Generating System. The engine is equipped with a smoke generating system which can be used to spray vaporized diesel fuel, from the vehicle’s fuel tanks, directly into the engine exhaust system. This creates a dense smoke screen to conceal the vehicle’s location and movements. 3. Detailed Description. a. Crankcase. The crankcase is a one-piece 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 thru studs 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 combustion forces over the entire crankcase. b. Main Bearings. The seven replaceable main bearings are steelbacked, 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. c. Crankshaft, Flywheel, and Damper. Details of the crankshaft, flywheel, and damper are shown in Figure 1. The key numbers in parentheses below refer to Figure 1 unless otherwise indicated. (1) Crankshaft Assembly. The crankshaft assembly (44) is a nitrided steel forging with seven main bearing journals and six crankpins. Each crankpin accommodates two opposing connecting rod assemblies (52). Flanges are provided on the crankshaft assembly for mounting the flywheel (13) on the rear end and crankshaft torsional vibration damper (51) on the front end. The crankshaft assembly and flywheel are both statically and dynamically balanced. The crankshaft torsional vibration damper is a precision viscous type and is replaceable only as an assembly. (2) Bearing Journals. All crankpin and main bearing journals are hollow to reduce weight. Holes are drilled diagonally through each main bearing journal and extend through the crank cheek and crankpin to provide a direct passage for oil under pressure to the connecting rod assemblies (52) and crankshaft main bearings. 0002 00-2 Change 1