Study on vibration characteristics of a locomotive with gear tooth root crack by simulation

Gear transmission is a key element in locomotives where it delivers the traction or braking powers between the motor and the wheelset. Its dynamic performance and service reliability have a direct effect on the performance of the locomotive. Gear failures, such as tooth crack and the induced tooth breakage, are likely to deteriorate the dynamic performance of the locomotive or make the train out of control, or even cause disastrous derailment. Fortunately, these failures will also vary the vibration responses of the locomotive, which enables the possibility of vibration-based fault detection for locomotives. In this study, vibration features of a locomotive when a tooth root crack fault is in presence in one of its gear transmissions. Here, the results for a healthy locomotive and a gear tooth cracked locomotive are compared to reveal the fault vibration features. Also, effect of the rail geometric irregularity excitation is also considered. It is proven that the rail geometric irregularity could slur frequency structure which brings a challenge to the fault feature extraction. Application of the time synchronous averaging (TSA) technique is proven to be effective for solving this problem.