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Q3. With reference to 2-Stroke Slow Speed Engine:

A. Sketch and describe Main Engine Exhaust Valve.

B. List out a procedure for test of Main Engine Exhaust Valve after overhaul.

Q5. Sketch and describe the arrangement of a main engine camshaft chain. Describe the repair procedure following fracture of one chain link during operation of the engine. Give possible reasons for the failure and explain how the chain is set initially at the correct degree of tension.

Q7. 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. A. Briefly describe the causes and effects of bacterial attack of lubricating oil.

B. Bacterial activity has been detected in the lubricating oil of the main engine fitted in the ship aboard which you are serving as 2ndeng. Write a letter to the owner/operator of the ship indicating the action you intent to take and offer suggestion to the avoidance of future incidents.

Q8. Explain why the use of residual fuels for the operation of large slow speed or of medium speed engines, may be responsible for the following problems with turbocharger nozzles, shrouds and blades and how in each, the problem may be minimized:

A. Build-up of deposits.

B. Hot corrosion.

C. Erosion (16)

Q7. Sketch and Discuss the precautions and protections that are provided to minimize the possibility of a diesel engine crank case explosion and the transmission of dangerous flame into the machinery space;

A. By design and equipment; B. By operating personnel

Q4. a) Enumerate the causes of vibration in diesel machinery and shafting. (5)

b) Describe procedures by which it may be reduced by operating personnel, suitable design and devices. (6)

c) State the possible effects of vibration on machinery and crewmembers. (5)

Q5. With reference to mechanical/hydraulic governors explain:

A. Why flyweights are driven at a higher rotational speed than the engine;

B.  How dead band effects are reduced;

C.  How hunting is reduced;

D.  How the output torque is increased.

With respect to control air supply system for Main Engine Control:

A. Define the essential conditions, which must be satisfied by the air supply for a pneumatic control system;

B. Sketch a control air supply arrangement and give a reasoned explanation for positioning of dryers and filters.