１　引言东风４型机车在运用过程中，其牵引电动机的牵引小齿轮破损经常发生，破损后造成的后果也比较严重，轻则发生电机转子轴颈拉伤，更换电机轴，严重的会使电机环火，电机无载转速飞升，造成无纬带崩开，电机转子报废，非正常磨耗还会造成从动大齿轮的磨损报废。因此，如 1 Introduction Dongfeng 4 locomotive in the use of the process, the traction motor traction pinion damage often occurs, the consequences of damage after the more serious, ranging from the occurrence of motor rotor shaft strain, replace the motor shaft, the serious will make the motor Ring of fire, the motor no-load speed soaring, resulting in non-latitude band collapse, motor rotor scrapped, non-normal wear and tear can also cause wear and tear of driven gear scrap. So, for example