Q.11 The lubricating oil supplied to the crankpin bearing in a marine diesel engine Ans. by internal crankshaft passages.
The internal passages in the crankshaft are made in such a manner, in case of small diesel engines where crankshaft size is comparatively small, that oil is supplied to the main bearing. From there to the passage in the crankshaft it is feed to the crank pin bearing. Thus avoiding the complicated piping to supply oil to the crankpin bearing and gudgeon pin bearing. This is applicable only in case of small crankshafts. Bigger crankshafts may fail under fatigue if the holes are drilled out for the passage of the oil. Hence in case of the bigger crankshafts, no drilling of the holes is done on the crankshaft and hence this method of lubricating the bottom end bearing and gudgeon pin bearing is not applicable. In that case, there is a separate supply of lubricating oil to main bearing and as well as to the crosshead bearing, which will be further bifurcated into two: the crosshead bearing and piston cooling, and the bottom end bearing, for lubricating.
Q.12 Gudgeon pin bearings are difficult to lubricate because of their oscillating motion and
Ans. (d) their position in the lubricating system.
As a gudgeon gearing is fitted between the 
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