EKM-Aug-2019

Q1. Explain the functional and constructional diffidence between the Torsional and Axial vibration dampers with the help of neat sketches, Explain the function of the side and Top bracing of the main engine.


Q2. What is “virtual tappet” in the hydraulically actuated air spring return exhaust valves, and how is it set. Explain why the damage occurs to the seats of the exhaust valves due to furrowing and cutting and how an incident of “valve drop” leading to extensive damage to running gear can occur.


Q3. With reference to the 4-stroke medium speed engines: A. Define the cause and effect of thermal stressing in cylinder Heads, liners and pistons. B. Explain why thermal stressing are aggravated with increase in cylinder bore. C. Explain how stress concentration and its effects are relieved by maintenance and operational practices.


Q4. How can an explosion occur in the starting air line of an internal combustion engine and how can the possibility of such an occurrence be reduced? Sketch and describe devices, which may be fitted to reduce the severity of such an explosion. State the attention which air starting valves should be given before stand by.


Q5. Sketch and describe Heavy fuel oil system of a large bore internal combustion engine and give temperature and pressure at important points. Discuss atomization, penetration and swirl and their inter relationship.


Q6. Discuss the consequences of failure to maintain correct clearances in the case of main diesel engine crankshaft and bottom end bearings. Sketch a bottom end bearing paying particular attention to the arrangement of ensuring uninterrupted flow of oil to the top end bearing.


Q7. With reference to main engine turbocharger; A. Explain why cleanliness throughout the turbochargers system is critical to engine performance? B. Describe in-service cleaning procedure for gas and air sides of a turbocharger indicating safety precautions to be observed?


Q8. While operating at Sea during rough weather conditions, fire sparks have been observed coming out from the chimney. On investigation, it has been observed that the fuel contains considerable quantity of water and sludge. As the Second engineer of the vessel. Explain: a. Immediate actions taken to rectify the problem. b. Precautions you take to avoid recurrence of this type of problem.


Q9. State how EACH of the following defects becomes apparent, describe its effect on engine operation or safety and indicate the corrective action required to restore normal engine condition;A. Leaking air inlet and exhaust valves; B. Leaking air start valve;C. Cracked cylinder liner; D. Broken piston rings.


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