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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)

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)

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. 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; (b) State the short-term action to be taken in order to minimize engine operational problem; (c) State with reason how future incident of this nature could be minimized

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)

Q3. 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. (16)

Q5. (a) Sketch and describe a device employed for continuous monitoring of the viscosity of heavy fuel oil being supplied to a main engine (8)

(b) Explain how the system employing the device described in (a) operates to adjust the fuel viscosity. (8)

Q9. (a) Describe how it is determined whether a crankshaft was twisted during a major “smash up” in a main engine.

(b) Explain where twisting is most likely to occur.

(c) Specify with reasons the degree of twisting that might be accommodated without correction

(d) Explain briefly what adjustments and precautions should be instituted when putting an engine with a twisted crankshaft back into service.

Q2. During your watch, main engine operation suddenly becomes erratic with speed varying widely even though fuel control remains at the value originally set:

a) State with reasons the possible cause of this behavior (8)

(b) Explain in detail how this cause can be traced, and the problems rectified. (8)

Q8. What is a “Cam"? Explain its function. With reference to its application in diesel engines

Discuss the requirement and the type of cam used in

a) Fuel Pump

b) Indicator drive

c) Inlet Valve

d) Exhaust Valve

e) Starting air distributor. (16)

Q1. What is the meaning of “de-rating” of machinery?

a) Explain the principles behind de-rating a ship propulsion engine as a retro fit. And the benefits. (8)

b) Can a de-rated engine be run at full power? If yes, under what conditions? (8)

Q7. Analyse the problem of cylinder liner lubrication with reference to oil injection timing relative to piston position, speed and direction of motion. Describe the worst effects of inaccurate lubricant injection timing and how it can have a detrimental effect on developed power in the cylinder. Describe with sketches the arrangement for conveying the oil through the cylinder jacket. (16)