Collision and wear are common phenomena in revolute clearance joints, caused by the positional deviation between the journal and bearing centers. The freedom of motion and contact–impact characteristics are reflected in the mechanism’s movement. The penetration behavior of the clearance joint is described using modified elastic contact model combined with Coulomb’s friction. In addition, the dynamic model of a high-precision mechanism with a clearance joint is established using Largrange’s equation. A dynamic performance experiment is also conducted. The results prove the validity of the proposed method. The kinematic accuracy of this mechanism is then used to evaluate the stability and motion error in a case study. Furthermore, the influence of the clearance joint on the dynamic behavior of the high-precision mechanism is thoroughly analyzed. The results show that the fluctuation range of the slider’s dynamic repeated precision for slider is only 0.022 mm under high-speed conditions, meeting the design requirement.

In this study, a dynamic response model that incorporates lubricated clearance is developed to examine the evolution of contact and friction in a mechanical system. The dynamic model of a lubricated clearance joint is established by considering the contact, friction, and hydrodynamics. The expression of contact force in normal and tangential directions is developed using elastic contact theory. The lubrication characteristics of a revolute joint are obtained using hydrodynamic theory, which is introduced into the simulation model. This case study is conducted to investigate the effects of design parameters on the dynamic stability of a mechanical system with a lubricated clearance joint. The results elucidate the relationship between lubrication characteristics and vibration response, offering valuable insights for the optimization of mechanical systems.

Joint clearances inevitably deteriorate kinematic accuracy and operational stability of heavy-load mechanical presses. Most existing studies focus on single-type clearances or uniform contact states, failing to reveal the coupled dynamic behavior of multi-type clearances with differentiated lubrication conditions. This work develops a five-degree-of-freedom coupled dynamic model for a double-crank mechanical press, integrating hydrodynamic lubricated revolute joints and dry contact–impact translational joints. Nonlinear dynamic responses under varying clearances, driving speeds and contact regimes are systematically analyzed. Results show that moderately enlarged translational clearance improves positioning accuracy by suppressing oil film whirl-induced chaos; lubricated revolute joints effectively isolate high-frequency impact energy via squeeze-film damping, and the system exhibits non-monotonic dynamic characteristics with speed. This study provides a theoretical basis for clearance matching and operating optimization of mechanical presses.

Brake-induced steering wheel shimmy is a critical nonlinear dynamic phenomenon that severely compromises vehicle handling stability and driving safety. While clearances in steering mechanism kinematic pairs are widely recognized as a primary cause of shimmy instability, the coupling effect of multiple concurrent clearances remains poorly characterized, particularly under transient braking conditions. In this work, a 5-degree-of-freedom non-autonomous dynamic model of brake-induced shimmy is developed using Lagrange’s equations. The model comprehensively incorporates the non-smooth contact behavior of multiple clearance joints, transient braking axle load transfer, and the longitudinal–lateral coupling nonlinearity of tires. The nonlinear dynamic evolution of the system is investigated through phase portraits, Poincaré sections, and continuous wavelet transform analysis. Numerical results demonstrate that multi-clearance coupling increases the peak shimmy angle by more than 40% compared to the single-clearance case. As the clearance magnitude increases from 0.05 mm to 0.40 mm, the system undergoes a transition from stable periodic motion to high-dimensional chaos, accompanied by a 67% reduction in vibration energy concentration at the 0.4 mm clearance level. This study elucidates the nonlinear mechanism underlying clearance-induced brake shimmy, providing a robust theoretical foundation for steering system parameter optimization and shimmy mitigation strategies.