Dynamic Characteristics Analysis of Gear Transmission System with Three Kinds of Bearings of a High-speed Train

The traction transmission system is a key part of high-speed electric multiple units (EMUs). It is crucial to the safe operation and dynamic performance of the train. A coupled dynamic model considering the gear transmission system of a high-speed EMU is established in this paper. The transmission system contains helical gear meshing, a gearbox, and three types of bearings: tapered roller bearings on the gear shaft, two cylindrical roller bearings and a four-point contact ball bearing on the pinion shaft. In the model, the rollers of cylindrical and tapered roller bearings are divided into multiple slices to obtain the load state of the bearing rollers. The gear transmission model is included in a vehicle-track coupling dynamics model to investigate the dynamics characteristics of the bearings of the transmission system of the high-speed EMUs. After validating the proposed model with field test results, the dynamic responses of gearbox components under track irregularities and traction torques are comprehensively investigated. The results show that the traction torque plays a dominant role in the gearbox bearing loads. Track excitation increases the contact load of the gearbox bearings, the tilt and skew angles of the rollers, and changes the force state of the rollers in different slices, especially tapered roller bearings. Under track irregularity, the maximum dynamic contact load of the tapered roller bearings on the wheelset increases by 486.8% and 394.1%, respectively. The standard deviation of the contact load between the roller and the raceway of NU215 and QJ214 bearings shows a bimodal distribution, with larger deviations when the roller enters and exits the contact area, and is most stable at the position of maximum contact load. The load distributions of the bearings in the front and rear gearboxes are different. The proposed model can also be used for bearing life, roller slip calculation, and gearbox bearing selection.