Q3: Your ship after having been accidentally grounded was taken to a dry-dock for inspection and necessary repairs. What defects would you look for in the following parts, that may have sustained damage due to grounding and suggest methods of repairs and tests that may be required to be carried out to the defects noticed:
A. Propeller and tail end shaft.
B. Main engine crankshaft.
Q3. A. Sketch a transmission shaft coupling which enables the propeller shaft to be withdrawn outward.
(a) describe the coupling and the method fitting and dismantling;
(b) state how the grip of the coupling can be checked when fitted;
(c) State what safety precaution should be taken when dismantling the coupling.
Q9. Misalignment of the Main shafting between engine and propeller causes bearing overloads and shaft stress.
a) State the difficulties associated with checking the shaft alignment and the reasons why results are unreliable due to external factors.
b) State the reasons for misalignment
c) Explain with a simple sketch how a bearing load is assessed.
d) Explain how uneven loading could be rectified
e) Why wear down in main bearings is critical to the condition of the condition of the crankshaft and propeller system.
Q3. With reference to main Thrust bearing of the pivoting pad type, explain with sketches where necessary –
a) The principle of operation of the bearing
b) The critical clearances and why they are critical?
c) How these clearances are adjusted
d) Why such bearings sometime overheat although the clearances are adequate?
e) How is the lubrication film between faces of collar and thrust pad maintained?
Q8. With reference to shaft alignment:
(a) Explain the meaning of fair curve or rational alignment;
(b) Shaft alignment is often verified using hydraulic jacks to obtain a simple graph. Sketch such a graph, indicating the following:
(i) Static load;
(iii) Influence number;
(c) Explain the limitations of checking shaft alignment solely by hydraulic jacking methods.
Q6. With reference to main shaft bearings that are excessively loaded or very lightly loaded state for each condition what are the;
a) Indications of the fault,
b) Effects on adjacent bearings
c) Remedial steps.
Explain why load distribution on main shaft bearings changes in service.
Q3. With reference to propeller shaft alignment:
a) state the objectives of a satisfactory alignment
b) state the conditions that must be met to achieve satisfactory alignment
c) explain what is meant by fair curve alignment.
d)Define "sag and gap" in shaft alignment calculation.