Cylinder Block and Cylinder Liners
A steel spacer plate is used between the cylinder head and the cylinder block. This plate serves two main functions:
- The spacer plate eliminates the counterbore in the cylinder liner flange.
- The spacer provides the maximum liner flange support area.
The cylinder liner flange sits directly on the cylinder block.
Engine coolant flows around the cylinder liners. This cools the cylinder liners. Three O-ring seals are at the bottom of each cylinder liner, and a filler band is at the top of each cylinder liner. These items form a seal between the cylinder liner and the cylinder block.
Pistons, Rings, and Connecting Rods
The piston has three rings:
- Two compression rings
- One oil ring
All three oil rings are located above the piston pin bore.
The two compression rings seat into an iron band. The iron band is cast into the piston. The pistons use keystone rings. Keystone rings are compression rings. These rings have a tapered shape. Notice that the piston groove also has a tapered shape.
The movement of the rings in the piston groove results in a constantly changing clearance between the ring and the groove. This action (scrubbing) results in both a reduction of carbon deposit and potentially sticky rings.
The oil rings are a standard type, and the oil rings are spring loaded. The holes in the oil ring return the oil to the crankcase.
The piston pin bore in the piston is offset from the center of the piston by 0.76 mm (.030 inch). This reduces engine noise and liner cavitation due to the piston slap. The piston contains a full floating piston pin that is held in the piston by two snap rings. The snap rings fit into grooves in the piston pin bore.
The piston pin end of the connecting rod is tapered. This provides more bearing surface at the area of highest load. The connecting rod is installed on the piston with the bearing tab slots on the same sides as the "V" mark on the piston.
Crankshaft
The crankshaft changes the combustion forces in the cylinder into usable rotating torque that powers the machine. A gear at the front of the crankshaft drives both the timing gears and the engine oil pump. The surfaces of the connecting rod bearing receive lubrication oil through passages that are drilled into the crankshaft.
A lip type seal and a wear sleeve are used to control oil leakage in the front crankshaft seal. A grooved seal assembly helps to prevent oil leakage from the rear of the crankshaft. The hydrodynamic grooves in the seal lip move any lubrication oil back into the crankcase as the crankshaft turns.
Vibration Damper
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| Illustration 1 | g00321767 |
Cross Section Of A Vibration Damper (1) Weight. (2) Case. | |
Twisting of the crankshaft occurs due to the regular power impacts along crankshaft's length. This is called twisting vibration or torsional vibration. A vibration damper is used to reduce any torsional vibrations. A vibration damper also stops the vibration from building up to the levels that can cause damage.
A vibration damper is installed on the front of the crankshaft. The damper has a weight in a metal housing. The space between the weight and the housing is filled with a thick fluid. The weight moves in the housing in an effort to limit the torsional vibration.
| NOTICE |
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Thoroughly inspect the viscous damper for signs of leakage or for signs of a dented (damaged) case. Either of these conditions can cause the weight to make contact with the case. This can affect the viscous damper's operation. |