Objective During the operation of metro vehicles, influenced by factors such as wheel-rail impact vibration and the internal structure of the axle-end grounding device itself, the carbon brush cables within the axle-end grounding devices are prone to breakage. Cable breakage not only disrupts the normal grounding return circuit of the train but also poses a major hidden danger to passenger safety and metro operation safety. Therefore, conducting an in-depth analysis of the causes of carbon brush cable breakage and formulating effective improvement measures is of significant engineering importance.

Method Combining the stress analysis of the application environment of the grounding device carbon brush cables and the morphological analysis of the cable and terminal fracture surfaces, the main factors leading to carbon brush cable breakage are explored. Optimization schemes for the grounding device carbon brush cables are proposed, including changing the terminal crimping form, optimizing the terminal angle and cable length, modifying the spring sheath length, and implementing auxiliary reinforcement at the terminal crimping joint. Through bench comparison tests and on-track actual vehicle tests, a comparative study on the performance of the optimized scheme and the original scheme is conducted.

Result & Conclusion  Vibration impacts and the internal structure of the grounding device are the primary factors causing the breakage of the carbon brush cables. Wheel-rail irregularities and the bending vibration of the axle subject the carbon brush cables to substantial long-term stress. The proposed improvement measures can alleviate stress concentration in the crimping area between the carbon brush cable and the terminal, reduce the dynamic strain of the cable during train operation, restrain the development of cable fatigue damage, and effectively extend the fatigue life of the carbon brush cables.