For improving the reliability of main bearing in large 2-stroke marine diesel engine, it is indispensable to grasp the journal movement behavior in main bearing with high accuracy. We have studied to disclose the journal movement behavior. Firstly, the journal movements of actual engines were measured. The journal center locus and the journal tilting angle were clarified. Secondly, a theoretical calculation model has been developed in order to simulate the journal movement behavior under uneven alignment between two adjacent main bearings. For confirming the validity of the model, calculated results were compared with measured results. The model was proved effective to simulate the journal movement in high accuracy. At last, by indicating an actual bedplate deflection owing to the loading of a vessel, the calculated journal movement results under the uneven alignment is compared with measured results. As the results, the developed model is able to simulate the journal movement under the uneven alignment. Considering the circumstances mentioned above, the model is proved effective to simulate the journal movement with high accuracy. The developed simulation technique of journal movement behavior has been applied in practical machinery design for high reliability.
