Engine Operation 10 UENR0623-02 The port for the inlet valve is on the top of the cylinder head. The port for the exhaust valve is on the right side of the cylinder head. The valve stems move in valve guides that are pressed into the cylinder head. There is a renewable oil seal that fits over the top of the valve guide. The valve seats and the valve guides are replaceable. The connecting rods (4) are machined from forged steel. The connecting rods have bearing caps (6) that are fracture split. The bearing caps (6) on fracture split connecting rods (4) are retained with bolts (7). Connecting rods with bearing caps that are fracture split have the following characteristics:
Pistons, Rings, and Connecting rods The splitting produces an accurately matched surface on each side of the fracture for improved strength. The correct connecting rod must be installed with the correct bearing cap. Each connecting rod and bearing cap have a unique serial number. When a connecting rod is assembled the serial numbers for the connecting rod and bearing cap must match. Crankshaft Illustration 6 g02859336 Typical example The pistons (3) 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 (9) is off- center in order to reduce the noise level.
The position pin (9) is retained in the correct position by two circlips (8). Illustration 7 g02841976 Typical example (1) Crankshaft gear (2) Crankshaft (3) Crankshaft thrust washers The crankshaft can be a spheroidal graphite iron casting. The pistons (3) have two compression rings (1) and an oil control ring (2). 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 crankshaft has five main journals. Thrust washers are installed on both sides of number 3 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. 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 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