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Q9. With regards to connecting rod ovality of four stroke diesel Engine.

Explain Following.

a) Importance of connecting rod ovality.

b) Method of measuring the connecting rod ovality.

C) Discuss the impact of ovality if it increases beyond the maximum allowable limit.

d) Method of ascertaining the elongation of connecting rod bolts.

Q4. A. Discuss the nature of the forces to which a main engine crankshaft is subjected in normal service and explain how the resulting stress are maintained at a safe limit by design and efficient maintenance respectively.

B. Indicate the circumstances under which the crankshaft may--

i. over stressed; ii. Become defective without being over stressed.

Q6. A. Describe how a crank pin bearing of a 2 stroke main propulsion engine is opened up for inspection;

B. Which half of the bearing is subject to greater wear?

C. What are the various causes of wear down of the bearing.

Q1. Explain why auxiliary engine bottom-end bolts are prone to failure, even under normal running conditions. Identify those features, incorporated into the design of bottom-end bolts, to inhibit failure. Explain how this tendency is either aggravated or inhibited during maintenance and what checks are to be carried out.

Q7. Fatigue is one of the main causes of crankshaft failure - A. Indicate on a sketch the most likely location of a fatigue crack; B. Explain how a fatigue failure is identified; C. Describe how a fatigue crack may be initiated; D. Describe, with the aid of sketches, the methods used to inhibit fatigue cracks.

Q5. A. Briefly describe any one of the manufacturing process involved in semi built or welded construction of crankshaft of large marine engine; B. Give a composition of material used; C. Draw a stress diagram for stress in web of a crankshaft.

Q4. Explain each of the following:

A. Why wear down in main bearings is critical to the condition of the crankshaft and propeller shaft system.

B. Why total reliance is placed on frictional grip in conventional built up crankshaft

C. Why hole oils are given large fillets in crankpin and journals.