Observations to Prevent Failure
Since there are so many ways in which a crankshaft might fail, it is important to know various checks and observations which need to be done regularly so that such a situation does not arise and given below are a few such important points.
Firstly as described in the previous articles a routine check on the crankshaft alignment is a must and this helps to detect any major defects that are in the process of development.
If the differences in the bearing wear are substantial this means that the cause for the same needs to be rectified. Sometimes this may be due to the use of main bearings having different material which could be due to a different manufacturer etc.
Since lubricating oil is an important ingredient of the lubricating system, care should be taken to ensure that only clean and proper grade oil is used which could otherwise lead to bearing damage and ultimately affect crankshaft alignment. Apart from being cleaned thoroughly by the lub oil purifier, the oil should also be regularly checked for its pH value to ensure that it is not acidic in nature.
Since the bedplate and the foundation bolts acts as a base for the proper support of the crankshaft both these should be kept in order. The bolts should be properly tightened while a rigid bedplate should be used which is of course more of a design issue rather than in the hands of the engineer on duty.
Finally since resonance can give rise to excessive forces, care should be taken to avoid operating the marine diesel engine at such speeds which gives rise to critical frequencies.
Having learnt so much about crankshafts in previous few articles, it is now time to move on to the next component of the marine diesel engines namely pistons.