COVER AS 1302677 - Caterpillar

Cylinder head
Illustration 2 g01336270
Typical cylinder head
The engine has a cast iron cylinder head. The inlet manifold is integral within the cylinder head. There are two inlet valves and two exhaust valve for each cylinder. Each pair of valves are connected by a valve bridge that is controlled by a pushrod valve system. The ports for the inlet valves are on the left side of the cylinder head. The ports for the exhaust valves are on the right side of the cylinder head. The valve stems move in valve guides that are machined into the cylinder head. There is a renewable valve stem seal that fits over the top of the valve guide.Pistons, Rings and Connecting Rods
Illustration 3 g01336272
Typical example
The pistons have a Quiescent combustion chamber in the top of the piston in order to provide an efficient mix of fuel and air. The piston pin is off-center in order to reduce the noise level.The pistons have two compression rings and an oil control ring. The groove for the top ring has a hard metal insert in order to reduce wear of the groove. The piston skirt has a coating of graphite in order to reduce the risk of seizure when the engine is new.The correct piston height is important in order to ensure that the piston does not contact the cylinder head. The correct piston height also ensures the efficient combustion of fuel which is necessary in order to conform to requirements for emissions.The connecting rods are machined from forged molybdenum steel. The connecting rods have bearing caps that are fracture split. The bearing caps on fracture split connecting rods are retained with Torx screws. Connecting rods with bearing caps that are fracture split have the following characteristics:
The splitting produces an accurately matched surface on each side of the fracture for improved strength.Crankshaft
Illustration 4 g01336274The crankshaft is a chromium molybdenum forging. The crankshaft has five main journals. Thrust washers are installed on both sides of number three main bearing in order to control the end play of the crankshaft.The crankshaft changes the linear energy of the pistons and connecting rods into rotary torque in order to power external equipment.A gear at the front of the crankshaft drives the timing gears. The crankshaft gear turns the idler gear which then turns the following gears:
Camshaft gear
Fuel injection pump and fuel transfer pump
Lower idler gear which turns the gear of the lubricating oil pump.Lip type seals are used on both the front of the crankshaft and the rear of the crankshaft.A timing ring is installed to the crankshaft. The timing ring is used by the ECM in order to measure the engine speed and the engine position.
Illustration 5 g01336276Gears and Timing Gear Case
Illustration 6 g01336278The crankshaft oil seal is mounted in the aluminum timing case. The timing case cover is made from pressed steel.The timing gears are made of steel.The crankshaft gear drives an upper idler gear and a lower idler gear. The upper