In the ultra-low temperature environment, the material properties of the bearing change, which puts forward higher requirements for the dynamic performance of the bearing cage. The bearings operating in ultra-low temperature environments commonly use solid lubricants. This study first focused on measuring the traction coefficients of molybdenum disulfide (MoS₂) solid lubricant in a nitrogen atmosphere, and the Gupta fitting model is constructed to derive the traction equation. Subsequently, the dynamic differential equation of angular contact ball bearings was established, and the stability of the bearing cage in a nitrogen environment was simulated and analyzed based on the dynamic model. The accuracy of the simulation model was verified through comparison. The results show that less than 10% of errors exist between the experimental data and the traction curve fitted by the Gupta model, and the stability of the cage is closely related to operating parameters and bearing structure parameters. Cage stability increases with axial load but decreases with radial load. The cage stability is optimal when the radial internal clearance of the bearing is approximately 0.06 mm. When other conditions remain unchanged and the ratio of the cage pocket hole gap to the cage guide surface gap is 0.2, the cage stability is the best. The research results will provide a foundation for the design and application of solid-lubricated angular contact ball bearings in ultra-low temperature environments.

The traction motor is a crucial component of high-speed electric multiple units, and its operational reliability is directly impacted by the temperature increase in the bearings. To accurately predict and simulate the temperature change process of traction motor bearings during operation, a fluid–solid–thermal simulation analysis model of grease-lubricated deep groove ball bearings was constructed. This model aimed to simulate the temperature rise of the bearing and the grease flow process, which was validated through experiments. The results from the simulation analysis and tests indicate that the temperature in the contact zone between the bearing rolling element and the raceway, as well as the ring temperature, initially increases to a peak and then gradually decreases, eventually stabilizing once the bearing’s heat generation power and heat transfer power reach equilibrium. Furthermore, the established fluid–solid–thermal coupling simulation analysis model can accurately predict the amount of grease required for effective lubrication in the bearing cavity, which stabilizes along with the bearing temperature. The findings of this research can serve as a theoretical foundation and technical support for monitoring the health status of high-speed EMU traction motor bearings.

Bearings operating in ultra-low-temperature environments are commonly lubricated with solid lubricants. This study first focused on measuring the traction coefficients of molybdenum disulfide (MoS₂) solid lubricant under various working conditions. Based on this data, the friction power consumption of the bearings was calculated and analyzed using a dynamic model. Additionally, experimental verification of the bearing friction power consumption in ultra-low temperature environments was conducted. The research findings will serve as a foundation for the application of solid lubrication bearings in ultra-low-temperature environments.

Oil–air lubrication technology is commonly utilized in the lubrication design of traditional components to reduce friction between contact pairs. This study focuses on testing the point-contact friction pairs of two quantitative valves using a self-made oil–air lubrication traction force machine with a G95Cr18 disk and ball as the friction pairs. The test data are analyzed using a four-parameter exponential model. Additionally, a calculation model of the oil–air lubrication flow field is established, defining boundary conditions and conducting flow field simulation analysis. The results of the ball and disk test show that the traction coefficient increases with load and decreases with entrainment speed. Furthermore, when the air-speed is 12 m/s, the traction coefficient is lower for the oil supply of 6 mL/min than for the oil supply of 1.5 mL/min. According to CFD analysis, the volume fraction of the oil phase in the contact area increases with the increase of entrainment speed when the slip–roll ratio is 0.1. The theoretical values from the four-parameter exponential model align well with the experimental results, and the fitting accuracy is higher than 0.95.

The numerical simulation of metal heat treatment is of great significance for the development of new materials or processes. The complex coupling relationship in metal heat treatment poses a huge challenge to the overall solution. A finite volume method based on the Crack–Nicolson (C-N) scheme with parallel algorithms is proposed for solving the coupling of metal thermal phase transition. Taking the quenching simulation problem of bearing rings as an example, the calculation accuracy and speed of this method were evaluated by comparing the results of the temperature field and phase transformation field obtained from the literature. In addition, grid independence analysis was conducted to demonstrate the rationality of the established model. The finite volume method using a hexahedral mesh C-N format improves the accuracy of calculations. Optimizing the equation form and using parallel algorithms have improved computational speed. In the trial example, in the 850 °C quenching simulation of GCr15, the outer ring of the bearing is composed of 89.1% martensite and 10.9% residual austenite. The results compare with test verification, which shows that the model performs well in the numerical simulation of metal heat treatment.