一、概况1974年9月初,成昆线快车开始装用4—2号低摩合成闸瓦。起初效果较好,因此在短期内就扩大装用至16列客车。经过冬季运行,至1975年4月初发现车轮出现热裂纹。对此进行了调查和分析,分析结果认为造成裂纹的原因主要是合成闸瓦的技术性能未达到要求,其次是机车操纵方法、车辆技术状态及车轮材质未达到规定要求。事后经过试 First, an overview In early September 1974, Cheng Kun line Express installed 4-2 low friction synthetic brake shoe. At first, the effect was better, so in the short term it will be expanded to 16 passenger cars. After winter operation, a hot crack was found in the wheel by early April 1975. The investigation and analysis indicated that the main reason for the crack was that the technical performance of the synthetic brake shoe did not meet the requirements, followed by the locomotive operation method, the vehicle technical condition and the wheel material did not meet the requirements. After the test