Department of automobile engineering



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Figure 8 CRANK-SHAFT
OUT OF ROUND:

The out of round wear in journals crankpin is due grip pressure the imposed on bearing and journal in power and compression strokes imposed during the intake and exhaust stroke since the crankpins are usually smaller in diameter having less wearing or they tend to wear out of crown more than main bearing.



TAPER:

If a journal is tapered it means that it has a smaller diameter on one end and a larger diameter on the other end. This is an undesirable condition however it is allowed if it falls within the tolerances of the engine manufacturer. Generally it is .0001 (1/10,000) of an inch. From one end of the journal to the other.

On crankshaft with drilled hole oil passage adjust materials in oil land to wear on one side of crankpin more than the other side this is caused by the oil hole in the crank case is drilled out an material to flow more readings to the side of the crankpin in direction of flow.

CHECKING THE CRANKSHAFT ALIGNMENT:

If an engine crankshaft is not correctly aligned in its bearings, it distorts and becomes subject to damaging stresses. Any misalignment causes a change in the distance between webs when the shaft revolves and can be detected by placing an indicating device between the webs.



The crankshaft alignment gauge is designed for this purpose. Its contacts are pointed and fit into dimples in the webs. A heavy spring pressure ensures that the gauge is retained but is free to turn in relation to the crankshaft and an adjustable balance weight restrains the gauge against rotation of the crankshaft so that the dial always faces the inspect.



Figure 9 CRANKSHAFT ALIGNMENT

INSPECTING CRANKSHAFT JORNALS:

If the main bearing journal of the crankpin is scrod at produce the central shaft should either or replaced right seal on the journal can be honest with oil stem polished with polishing paper. The journal that in the bearing rotates in cost inset type bearing with no preview for adjustment need not be regards. Journal that bearing worn evenly wormless then 0.001 in the taper +less then 0.001in out of round.






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