TM-9-2815-220-24 Maintenance Manual for AVDS-1790-2CA AVDS-1790-DA and AVDS-1790-2DR Engines Download
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TM 9-2815-220-24 THEORY OF OPERATION 0004 00 ENGINE COMPONENTS (Continued) Crankcase (Cylinder Block): The crankcase is a solid metal (aluminum) casting that makes up the bulk of the engine. The cylinder mounting holes and various oil passages are bored in the block. It is a one-piece aluminum casting with forged aluminum main bearing caps. Seven main bearing caps function as an integral part of the crankcase. Each cap is secured with four studs and four slotted nuts in addition to two through bolts that clamp the main bearing cap in 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. IMPORTANT Main bearing caps must be kept in their original location. They are numbered 1 through 7 beginning at the front (damper) end of the crankcase. The caps are secured to the crankcase before being line- bored making them an integral component of the crankcase. The seven replaceable main bearings are steel-backed, split type, having copper-lead alloy bearing surfaces. The center main bearing is double-flanged with bearing material to control crankshaft endplay and thrust. Crankcase Main Bearing Caps WP 0004 00-13