Paper 6: Alignment Investigation following a Medium-Speed Marine Engine Crankshaft Failure

Abstract

The multiple fracture, apparently without warning, of the crankshaft of one of a pair of medium-speed propulsion engines in a modern cargo ship in mid-Atlantic led to a programme of tests, involving many alignment measurements, chiefly on a sister ship. The damage to the engine is reviewed and an account is given of the investigation into the cause of failure. The measured values of alignment are recorded, together with changes of alignment due to temperature variations of the machinery, the lubricating oil, and the cooling water, and to cargo loading and distribution. Conclusions are stated and a set of rules, which have been supported by subsequent experience, are postulated.