Surface wear evolution of traction motor bearings in vibration environment of a locomotive during operation

Wear is a major cause of bearing failure,however,compared with other impact failures,smooth wear is often neglected because of its slow gradualness.In a locomotive,under the effect of the intensified wheel-rail interaction and gear mesh,the surface wear can increase the radial clearances of motor bearings,trigger abnormal vibration and noise,and adversely affect the efficiency and safety of the traction motor.In this study,considering the mechanical structure of the traction motor,a locomotive-track spatially coupled dynamics model with traction power transmissions(LTMM)is adopted to provide accurate dynamic loads and obtain the dynamic responses of the system.From the perspective of contact stress and relative skidding at the roller-race interface,the causes and evolution of motor bearings surface wear are analyzed.The results indicate that the wear of inner races of motor bearings is uniform.The outer races of the driving/non-driving end bearings(DB or NDB)are worn in the loaded/main loadbearing regions.The increasing surface wear can increase the internal dynamic forces(e.g.,the centrifugal force of rotor and unbalanced magnetic pull)induced by the instantaneous eccentricity of the rotor,intensify the interactions between the roller and races,and deteriorate the vibrations of the traction motor and its neighboring components in the locomotive.In addition,the effects of the friction coefficient at the roller-race interface and track random irregularity are analyzed.This study offers a theoretical basis in service life prediction and design of the motor bearings.