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An owner of a bulk carrier had suffered a failure of main bearings 3 and 4, which caused severe damage to the crankshaft journals. Spark erosions were determined as the cause of the damage. They occur when a voltage is discharged between the main bearing and the shaft journal, which is normally eliminated by the onboard earthing device, which, however, was not working on this vessel. For this ship, it caused a development of heat in journal 3 and 4, which consequently led to a collapse of the bearing supports and even damage to the bedplate. Therefore, a new crankshaft was required, and the bedplate needed machining. After almost 7 months, this big overhaul was successfully completed and the ship is now fit for service again.
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