Q4. (a) describe a method of checking main transmission shaft alignment which does not involve the removal of shaft coupling bolts. (5)
(b) State why the shaft alignment should be checked when the ship is afloat in a light ship condition. (1)
(c) A shaft system is found to be excessively misaligned so as to cause serious bending of the shaft. State what effect this could have on EACH of the following:
(i) the shaft coupling bolts; (1)
(ii) the shaft bearings. (1)
(d) State, with reasons, which of the effects in part (c) would cause the most concern. (2)
>> Question intends to check your competence in shafting system. The answer describes a “Hydraulic Jacking” method which is commonly used.
Why not the conventional methods?
>> Alignment can be checked with conventional methods, employing light and targets, laser or measurements from a taut wire. There is, however, a continuity problem because the line of sight or taut wire cannot extend over the full length of an installed shaft.
(a) Mostly all right, although a few candidates described crankshaft deflections.
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