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Q5. With reference to the crankshaft and running gear of an engine, explain static balance, Dynamic balance, Torque reaction couple, and Critical speed

Q9. With reference to crankshafts, explain EACH of the following:

A. The cause and effects of torsional vibration;

B. The term critical speed indicating why it can be a problem;

C. The term fatigue cracking and state, with reasons, TWO factors of crankshaft operation which have greatest influence on the likelihood of fatigue cracking

D. How a torsional vibration damper can reduce the effects of torsional vibration

Q4. Fatigue is one of the main causes of crankshaft failure.

A. Indicate on a Sketch the most likely location of a fatigue crack;

B. How is a fatigue failure is identified;         C. Describe initiation of a fatigue crack;

D. Sketch and Describe the methods used to inhibit fatigue cracks

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.

Q9. Sketch and describe the -different types of Crankshafts used in Marine engines. Also describe the process of Induction Hardening performed on crankshafts and give the advantages of this process for the crankshafts.

Q8. A. Discuss the principal forces a large diesel engine crankshaft must withstand while in service and how the stresses resulting from these forces are kept within acceptable limits by good design and operation criteria; B. Discuss the manner in which the crankshaft may be overstressed and the consequences arising there from.

Q3. A. Compare the advantages of forged and built-up crankshafts with special reference to the magnitude of the stresses in the cranks; B. How would you check the deflections by means of a dial gauge through one revolution of the shaft? C. How are the readings obtained interpreted?  D. How wear is down measured?

Q8. With reference to Main engine crankshafts:

a) Explain the term axial vibration

b) Describe, with the aid of a sketch, how axial vibration may be minimised

c) State with reasons which bearing would be most at risk due to the effects of axial vibration

d) Describe how damage to the bearing stated in part (c) may be repaired.

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.

Q5. Crankshaft deflections taken from a large slow speed engine show an apparent alignment problem.

a) (i) Describe the investigation to find the actual degree of misalignment. (4)

(ii) State FOUR possible causes of the misalignment. (4)

b) State the influence of changes of hull loading, sea water temperature and the temperature of the deck on crankshaft alignment. (4)

c) State why bearing wear may be a result of misalignment rather than a cause. (4)

Q2. (A) Explain why crankshaft deflections are taken. (4)

(b) Write a procedure for the taking of main engine crankshaft deflections. (8)

(c) Explain the action to be taken if some crankshaft deflection readings are outside acceptable limits. (4)