4. (a) Describe how unequal loading of main transmission shaft bearings may be partially corrected at sea.
(b) Suggest, with reasons, what remedial action should be taken upon arrival in port.
(c) State the indication, while at sea, that unequal loading of such bearing exists.
Class 3
1. How is alignment of a crankshaft checked? Does the loaded condition of the ship have any effect on alignment?
2. What are the forces on a diesel engine crankshaft and are these forces uniform along the length of the crankshaft? Give reasons for your answer.
3. What is the purpose of putting a thrust bearing between the main engine and the propeller? How is the thrust bearing cooled?
4. Explain how a variable pitch propeller operates.
Test Examples 7
Class 1
1. (a) Draw a line diagram of an accommodation air conditioning plant, labeling the principal components and showing the direction of air flows in all ducts.
(b) Explain why humidity control is essential for comfort.
(c) State how ambient temperature affects humidity control.
(d) Give a reason why compensation for air losses is necessary and how it is accomplished.
2. (a) Identify, with reasons, those properties of Freon which makes it such an attractive refrigerant.
(b) Give reasons why each of the following gases has fallen into disfavour as a refrigerant:
(c) Carbon dioxide
(d) Ammonia
(e) Methyl chloride