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.