How to calculate misalignment of crankshaft in main engine? What may be the reasons of misalignment?


Crankshaft deflections are measured to detect the misalignment of main bearings. The misalignment occurs due to bearing wear or deflection of crankshaft. The horizontal and the vertical misalignment are checked.

  • Bearing temperature increases
  • Damaged bearings
Conditions under which crankshaft deflection to be taken:
  • Ship should be afloat (i.e. not in dry dock)
  • Calm weather
  • Comparison should be made under same temperature and loaded condition

The crankcase alignment is checked using a dial gauge. The gauge is fitted between the adjacent webs, opposite the crankpin at half of the diameter from the shaft centre. The dial gauge measures the crank web spread at different angular position of the shaft.

About the author

Anand Gautam

Anand Gautam is a marine engineer, Graduated from M.E.R.I. Mumbai. He likes to sail onboard ship and is one who is passionate about his job. He loves to share his knowledge, information, and ideas to everyone in a simplified way just for his satisfaction.

1 Comment

  • Why fore end and most aft end unit’s (main bearing ) deflection result are quite differ from others?

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