１　问题的提出东风５型机车主接触器触头烧损现象在我段时有发生。主触头表面经常烧出大小不一的金属瘤或深浅不等、形状各异的麻坑，造成主触头接触不良，需要经常维修打磨，严重的还需更换。这不仅增加了工人的工作量和维修费用，也影响了生产。２　原因分析　　图１为东风 1 questions put forward Dongfeng 5 locomotive main contactor contact burning phenomenon occurred in my time. The main contact surface often burned metal tumors of varying sizes or shades of unequal shape of Ma Hang, resulting in poor contact of the main contacts, the need for frequent maintenance and grinding, serious need to be replaced. This not only increases the workload and maintenance costs of workers, but also affects production. 2 reasons analysis Figure 1 for the east wind