某地铁受电弓拉杆球铰轴承在运行过程中发生失效断裂。采用宏观分析、断口分析、金相检验、硬度测试及化学成分分析等方法对球铰轴承的失效原因进行了分析。结果表明：该受电弓拉杆球铰轴承的断裂模式属于高周低应力疲劳断裂。球铰轴承在服役过程中承受频繁的振动和交变载荷作用，折角处的微裂纹成为疲劳裂纹源区，裂纹在交变载荷作用下不断扩展，最终导致球铰轴承失效断裂。

The ball socket bearing of pantograph pull rod in a metro failed and fractured during operation. The failure causes of ball socket bearing were analyzed by means of macro analysis, fracture analysis, metallographic examination, hardness test and chemical composition analysis. The results show that the fracture mode of ball socket bearing of pantograph pull rod belonged to high cycle and low stress fatigue fracture. In the service process, the ball socket bearing was subjected to frequent vibration and alternating load. The micro cracks at the corner became the source of fatigue cracks. The cracks propagated continuously under the alternating load, which eventually led to the failure fracture of the ball socket bearing.