Author: Hudson, RJF;
Published: 7
March
2007
| Date Received: 5
February
2007
Abstract
The author discusses the failure in service of the crankshaft of a 670mm bore Doxford LBD4 marine diesel main engine caused by cooling water leakage through minute cracks in a cylinder liner, adjacent a fuel valve. The water passed into the cylinder combustion space formed by two opposing pistons, in one of the cylinders. The hydraulic shock caused crankshaft journal slippage and major axial misalignment, with consequential main bearing and other damage. This occurred when the engine was wrongly tested using starting compressed air without first checking the main machinery by slowly rotating it once or twice, using the electric driven mechanical crankshaft turning gear.
Any return to service by such an affected vessel usually requires removal of the crankshaft from the engine for its repair or renewal. This would always require a lengthy lay-up of the ship at a dockyard and be associated with great allied costs.
Using four tonnes of liquid nitrogen, the author recounts how the crankshaft of the MV Eastern Rover was successfully restored to operational alignment afloat. The bearing damage was also repaired and realigned afloat, with full cargo intact, at Moji, Japan, where the casualty occurred.