1　组合活塞的故障分析1．1　活塞环槽的磨损　　活塞顶环槽磨损是导致活塞失效的主要原因。从许多机务段反馈情况来看，一般机车运行 2 5万ｋｍ时，第一道环槽磨损为 0 0 5～ 0 2 0ｍｍ，其主要原因为：①机车高速重载，中修里程延长；②活塞与缸套不匹配，性能差，寿命短； A combination of piston failure analysis 1.1 piston ring groove wear piston ring groove wear is the main reason leading to the failure of the piston. From the feedback of many locomotive depots, the wear of the first ring groove is 250 ~ 200mm when the general locomotive runs 25,000 km. The main reasons are as follows: ①The locomotive is overloaded at high speed and the mileage of middle repair is extended; ② Piston and cylinder liner does not match, poor performance, short life expectancy;