统计资料表明,在有些国家,例如苏联,他们的新发动机,尤其是大修后的发动机,其寿命分别低于各自的标准定额。其原因,他们的专家认为与客观上的使用条件,如道路差,保养欠佳;主观条件如司机的驾驶技术差,平时保养检查不及时等有关。但是,即使是性能良好的发动机,随着使用时间的增长,其技术状态总会恶化的。尤其象缸套一活塞、曲轴轴颈和轴承及其它一些配合副,非得拆修不可。通常,又正是这些配 Statistics show that in some countries, such as the Soviet Union, their new engines, especially overhauled engines, have their lifetimes below their respective standard quotas. The reason, their experts believe that objective and conditions of use, such as poor roads, poor maintenance; subjective conditions such as driver’s driving skills is poor, peacetime maintenance inspection is not timely and so on. However, even with a well-performing engine, the state of the art will always deteriorate as time goes by. In particular, such as a cylinder liner, crankshaft journal and bearings and some other co-deputy, must be overhaul. Usually, these are the same ones