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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.

Q7. With reference to medium speed engine cylinder liners:

A. Explain the cause and effects of Polishing or glazing;

B. Describe, with the aid of sketches, an anti-polishing ring and how it is fitted in the liner;

C. Explain the action of anti-polishing ring during the operation of the engine.

Q3. Discuss critically the following alternative types of main propelling machinery for installation in a proposed new ship - A. 2 stroke single acting cross head type slow speed engine; B. 4 stroke single–acting with reverses / reduction gear.

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.

Q5. Give a list of the properties or tests by which distillate and blended fuels may be specified or decisions be made on their fitness for use. Name the properties or constituents that may be found in a blended fuel having a high viscosity and high carbon content. Explain how they may cause problems in engine operation

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.

Q4. Misalignment of the main shafting between engine and propeller causes bearing overloads and shaft stress;

A. State the difficulties associated with checking shaft alignment and the reasons why results are unreliable due to external factors;

B. Explain with a simple sketch how a bearing load is assessed.

C. Explain how uneven loading could be rectified

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.

Q8. (A) A set of indicator diagrams including draw cards has been taken for a main diesel engine, noted that compression curve is normal. Examine critically and give reasons for following observations.

i. The maximum pressure is lower;

ii. The maximum pressure is higher;

iii. The expansion curve is lower;

iv. The expansion curve is higher.

(B). Describe how the faults as mentioned above can be rectified