BREAKDOWN OF THE DRIVE GEAR IN AN AUXILIARY ENGINE :
About 6 months back on board, a running A/E on load, high CW temperature alarm came. The St/by A/E was started and put on load. The running A/E offloaded and inspected. The C.W pr-gauge was not showing any reading and some abnormal noise was heard from CW pump. All precautions observed, pump was removed and checked.
The C.W. p/p gear found sheared off and the main drive gear also found damaged. Upon investigation it was found that same incident happened about 5 months back. When they fitted the main drive gear it was not fitting properly in the boss which was fitted to crank shaft. So they machined the boss so that the drive gear can be fitted on to the boss.
It was assumed that the machinery had created more wear between boss and drive gear which in turn caused more back lash in the mating gear, and this in turn resulted in quick wear down and damage. When new spares received all the measurements were taken into account and gears were fitted. After trials, and frequent checks were made. The gears were found working in good condition.