The axial piston pump (APP) is the core power component of hydraulic systems. Its friction pair wear can cause the degradation of piston pump performance until the function is completely lost or the service life is terminated. The slipper pair, prone to wear failure, is selected as the research object in this paper. The prediction method for the eccentric wear of the slipper pair is established, and the gradual change rules of the performance with wear accumulation are explored. The micro-surface rough peak contact and the stress state of the slipper pair are analyzed, and the mixed lubrication model of the slipper pair is established based on the elastohydrodynamic lubrication (EHL) model of the slipper pair. Grid discretization of a sealing belt of the slipper pair is carried out based on two-body abrasive wear and Archard adhesive wear models to improve the prediction method for eccentric wear of the slipper pair. The effectiveness of the proposed method is verified by a surface morphology analysis of the worn slipper. The results showed that the wear depth and wear width of the outer edge of the slipper bottom surface are positively correlated with the oil discharge pressure and the inclination angle of the swashplate, and negatively correlated with the rotational speed and the dynamic oil viscosity. The outer edge of the slipper is wedged after eccentric wear, and the hydrodynamic effect of the lubricating oil film of the slipper pair is enhanced. Hence, proper wear can improve the lubrication performance of the slipper pair.

This research investigates the dynamic mechanism arising from the coupling between multi-path stiffness modulation and geometric eccentricity in multi-stage gear transmission systems (MGTS) for high-end equipment. The study aims to address the critical challenges in vibration suppression and precision control for such systems. A lumped parameter model integrating translational and rotational degrees of freedom was established, and an analytical method for three-path stiffness modulation based on center distance fluctuation, pressure angle reconstruction, and contact ratio transition was proposed. The influence of geometric eccentricity on the dynamic characteristics via the combined action of stiffness excitation and displacement error was then systematically analyzed. It was found that a strong nonlinear coupling exists between the eccentricity ratio and the initial phase difference: the combination of extreme asymmetry and an anti-phase condition markedly amplifies the stiffness modulation amplitude, inducing severe vibration, while symmetric eccentricity coupled with phase optimization effectively mitigates these oscillations. The feasibility of the established model was verified experimentally. The simulated and measured frequency spectra showed good agreement at the meshing frequency and its major sidebands, thereby demonstrating the accuracy of the stiffness-error coupling mechanism. Ultimately, a dynamic performance-based “parameter design safety domain” was constructed, which explicitly defines a low-vibration design interval centered on the eccentricity ratio and phase difference. This work thereby not only deepens the theoretical understanding of the error-stiffness-vibration coupling mechanism in the MGTS but also provides theoretical support and a practical guide for the dynamic design, vibration suppression, and operational optimization of high-precision gear transmission systems.

To address the challenges of strong electromechanical coupling, nonlinear friction, and poor disturbance rejection in semi-direct-drive scraper conveyor systems under complex coal mining conditions, this paper aims to propose a high-performance drive control strategy that balances dynamic response speed with steady-state operational smoothness. First, an integrated electromechanical coupling dynamic model incorporating Permanent Magnet Synchronous Motor (PMSM) vector control and the time-varying meshing stiffness of a two-stage planetary gear train is established. Subsequently, a Sliding Mode Control (SMC) strategy optimized with a saturation boundary layer is designed and compared with traditional Proportional-Integral (PI) control under multiple operating conditions. Time-frequency domain analysis indicates that SMC significantly enhances the dynamic stiffness of the drive system. Under sudden load change conditions, the speed recovery time is shortened by approximately 76%, and the steady-state error is reduced by 37% compared to PI control. Microscopic characteristic evaluation based on FFT and Total Variation (TV) metrics reveals that SMC achieves active disturbance rejection through spectral broadening of the electromagnetic torque. Crucially, the steady-state cumulative control effort of SMC is equivalent to that of PI, implying no additional mechanical stress burden, while the equivalent dynamic transmission force fluctuation in the mechanical chain is reduced by about 3%. The study confirms that the proposed strategy successfully achieves a synergistic optimization of “macroscopic rapid response” and “microscopic smooth operation,” providing a theoretical basis for the high-precision control of heavy-duty underground transmission equipment.