PULLEY AS-IDLER 1154204 - Caterpillar

Cylinder Block and Cylinder Head
The cylinder block has four cylinders which are arranged in-line. The cylinder block has five main bearings which support the crankshaft. Thrust washers on both sides of the center main bearing control the end play of the crankshaft.A cylinder head gasket is used between the engine block and the cylinder head in order to seal combustion gases, water, and oil.The engine has a cast iron cylinder head. An inlet valve and an exhaust valve for each cylinder are 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.Pistons, Rings, and Connecting Rods
The pistons have a 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 skirt has a layer of graphite in order to reduce wear.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.A piston and connecting rod are matched to each cylinder. The piston height is controlled by the length of the connecting rod. Six different lengths of connecting rods are available in order to attain the correct piston height. The different lengths of connecting rods are made by machining the small end bearing off-center in order to form an eccentric bearing. The amount of the eccentricity of the bearing creates the different lengths of the connecting rods.Each cylinder has a piston cooling jet that is installed in the cylinder block. The piston cooling jet sprays engine oil onto the inner surface of the piston in order to cool the piston.Crankshaft
The crankshaft changes the combustion forces in the cylinder into usable rotating torque in order to power the engine. Vibration is caused by impacts from combustion along the crankshaft. The vibration forces are minimized by the use of a vibration damper. The vibration damper is located on the front of the crankshaft.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
Lower idler gear which turns the gear of the lubricating oil pumpLip type seals are used on both the front of the crankshaft and the rear of the crankshaft.Camshaft
The engine has a single camshaft. The camshaft is driven by an idler gear in the front housing. The camshaft uses only one bearing on the front journal. The other journals rotate in the bore of the cylinder block. The front bearing and the camshaft bores in the