Dynamic analysis of rail gearbox bearings

Track and railcar wheels can wear and develop flat spots during use that create vibration and high acceleration shock loading conditions in axle-mounted gearboxes. It is important to understand how these dynamic conditions affect gearbox bearing durability during bearing design and selection. A multistep dynamic analysis process for linking railcar vibration conditions to bearing component motions is presented. Field-relevant vibration conditions are applied to a model of a rail gearbox input shaft supported by two tapered roller bearings. Recently developed bearing load-displacement models are used to calculate the shaft and relative raceway displacements under these imposed vibration conditions. The calculated raceway displacements are then used as inputs for dynamic calculations of roller-cage impact forces within each bearing. Knowledge of the detailed dynamic conditions within the bearings leads to improved bearing designs that reduce the likelihood of cage damage.