Analysis of the causes of damage to frame bearings and crankshaft of Caterpillar 3412 diesel-generator

The results of the analysis of the causes of damage to the frame bearings of the Caterpillar 3412 marine diesel engine used as part of an auxiliary diesel generator (ADG) are presented. During attempts by the crew of the QUARTZ vessel to launch the parallel operation of ADG No. 1 and No. 3 (after replacing their diesel crankshaft speed regulators (actuators)) there was an emergency stop of the ADG No. 1. When disassembling the diesel engine, damage was found to the frame bearing No. 4 and the corresponding frame neck of the crankshaft. The cylinder block in the area of the frame neck No. 4 had a characteristic white coating, which indicated local overheating. The shipowner's specialists identified the main cause of the described injuries - a violation of the lubrication conditions of the crankshaft frame bearing assembly No. 4. The following possible initial causes of damage are considered: the use of a brand of lubricating oil that does not comply with the diesel operating instructions or has characteristics that do not meet quality standards; diesel operation with an unacceptably low or high oil level in the crankcase; poorly performed diesel repairs; violation of the rules of technical operation of diesel by heavy mechanics, as well as other reasons. The induction of scientific and practical knowledge in the field of operation and repair of marine diesels, Caterpillar 3412 engine operating instructions, authors' own research, and statistics on damage and failures of marine diesel crankshafts is applied. The most probable cause of the damage has been determined, which consists in a combination of the following factors: multiple starts of the diesel engine with a violation of the start procedure with an excess of the crankshaft speed and an inappropriate quality and quantity of oil in the crankcase of the diesel engine. The research is of a practical nature, and its results can be used to familiarize ship mechanics and specialists in the field of operation of high-speed marine diesel generators.