Fault Vibration Features of Heavy-Haul Locomotive with Tooth Root Crack in Gear Transmissions

High-power heavy-haul locomotive has already been the development trend of Chinese heavy load freight. As a vital equipment of the locomotive system, gear transmission system is usually employed to deliver the traction or the braking power between the traction motor and the wheel/rail contact interface. The increasing dynamic load of the gear transmission induced by the raising of locomotive traction or braking power is likely to cause failures to the gear transmission system, which will affect the reliability and safety of the railway vehicles. This paper established a spatial dynamics model of high-power heavy-haul locomotive considering dynamic effect of the gear transmission based on the multibody dynamics theory in which the gear transmission is established as a sub-model. The time-varying mesh stiffness of the gear pair with tooth root crack was obtained by `slice method' which is an analytical mesh stiffness calculation approach based on the potential energy principle. The fault vibration characteristics of the gear transmission under the complicated excitations from the wheel/rail nonlinear contact, the rail geometric irregularity, and the periodic gear mesh process are studied.