Diesel engine crankshaft journal bearings failures: Case study

Wear as a tribological process has major influence on the reliability and life of engine crankshaft bearings. The importance of field examinations of bearing failures due to wear is very well known. They point to the possible causes of wear and to the necessary treatment for its reduction or elimination. The paper presents the results obtained by examining 616 crankshaft bearings, damaged by different mechanisms. The bearings were installed in high-speed diesel engines, and were gathered for two years, during general repairs of the engines (overhaul), i.e. after 3000-5000 working hours. After the examination of the bearings, the fault tree analysis (FTA) was performed to determine the root causes for engine bearing failures. Each type of damage that was identified was illustrated with an appropriate high-resolution photograph. The investigations show that the basic and most conspicuous types of damage which cause bearing failures are abrasive, adhesive and surface fatigue wear. The paper also considers the effects of the place of installation and type of bearing material in respect to each type of wear.