1.前言 DD51型机车的DML61Z型柴油机自出厂以来运用时间约达20年,由于各部件的老化,使柴油机的故障率增大。尤其突出的是机体老化造成气缸套裂纹。仅1984年度一年间,耗费在这方面的资金就达4000万日元左右。此外,在为解决与柴油机有关的问题而出差的任务中,与气缸套问题有关的占一半以上。1984年度故障件数共28件,总计出差人数达126人,这不仅在经费上造成极大损失,而 1. Introduction DD51 locomotive DML61Z diesel engine from the factory since the use of time of about 20 years, due to the aging of the components, so that the failure rate of diesel engines increased. Particularly prominent is the aging of the cylinder liner caused by cracks. In the year of 1984 alone, about 40 million yen was spent in this area. In addition, more than half of the problems associated with cylinder liner problems were encountered in missions to address diesel-related issues. A total of 28 pieces of fault in 1984, a total of 126 people on a business trip, which not only caused significant financial costs, and