Investigation of diesel generator shaft and bearing failures

A shaft failure in a 634 kW diesel generator after 4000 hours of operation required investigation, especially when similar sets began to show signs of excessive bearing housing wear. The failure was found to be due to torsional fatigue caused by operation at an unforeseen resonant condition. The damage to the bearing housing of this type of set was also attributed to this behaviour. Replacement of the bearings and housings and redesign of the flexible coupling has been undertaken to prevent further failures. Modifications to design procedures are now being adopted to ensure similar problems do not occur in other existing or new machines