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Q3. With reference to the Crosshead of Large two-stroke engines:

A. Explain how crosshead and guide shoe clearances are checked, in large 2 stroke engines. (8)

B. Explain how crosshead alignment is checked and adjusted. (8)

Q6. Write short notes on:

(a) Main air starting valves (4)

(b) Exhaust valve rotator (4)

(c) Scavenge relief valve (4)

(d) Function of Labyrinth Seals in turbocharger (4)

Q4. In a situation where the main engine control system suddenly fails, and it is not possible to rectify this immediately

A. Explain the action that a 2nd engineer should take. (8)

B. State the instruction that the 2nd engineer should issue in order to ensure the continued safe and effective operation of the engine. (8)

Q5. A large marine diesel main propulsion engine, speed fluctuates all the time during the voyage. Make written statements to the chief engineer explaining the observation of various engine parameters, during the voyage which could be indication of some fault, causing engine speed fluctuation. (16)

Q5. A. Describe the events leading to a crankcase explosion.

B. How is overheating indicated other than by a mist detector. (6)

C. How is severity of a crankcase explosion controlled. (5)

D. Discuss the action required when overheating is indicated. (5)

Q8. (a) Explain briefly how the different moving parts of a main engine are subjected to various stresses. (8)

(b) Name the stresses and justify by stating how they originate. (8)

Q6. A. Sketch and describe a pneumatic control system for controlling temperature of main engine lubricating oil at outlet of the cooler (6)

B. Explain why air supplied to a pneumatic control system must be free from dust and water (4)

C. Describe how above impurities are removed (4)

D. State the possible consequences if the air supply is contaminated. (2)

Q7.a) Explain the function of the crosshead guide shoe in a main engine. How is the crosshead guide shoe lubricated? (8)

b) Briefly discuss the maintenance carried out on guide shoe. How can improper maintenance affect the engine’s operation and lead to potential damage. (8)

Q8. Recent experience has shown persistence damage occurring on seating faces of main engine exhaust valve, which is not confined to any particular unit.

(a) State with reason the possible causes. (6)

(b) State the short-term action to be taken in order to minimize engine operational problem. (5)

(c) State with reason how future incident of this nature could be minimized. (5)

Q9. With reference to engine inlet and exhaust valves:

(a) State why tappet clearance is essential and why it must be periodically checked. (6)

(b) List with reasons the likely consequences of excessive and insufficient tappet clearance. (4)

(c) State how carbon build-up can occur during engine running and indicate the possible effects on cylinder performance. (6)

Q7. a) Give reasons why cracks occasionally develop in large piston crown. State to what extent this cracking is considered of consequence. (8)

b) State how it is dealt with in the following instances - A. Fine hairline; B. Localised and shallow crack. (8)

Q1. (a) How is fuel (HFO) for a marine diesel engine (main engine) being delivered from a fuel oil storage tank up to the combustion chamber? Explain with a line diagram. (10)

(b) What is the significance of the following:

          (i) Heating arrangement with temperature control. (3)

          (ii) Prevention of air lock in the system. (3)