Dynamic Behavior of Rack Vehicle System Under Offset of Gravity Center

Addressing the problem that the rack vehicle dynamic characteristics are affected by the gravity center offset of the rack vehicle on a large slope, based on the analysis of the mechanism of gear-rack meshing disturbance, considering the disturbance effect of gear rack meshing impact and wheel/rail dynamic contact behavior, and the effectiveness of the model was verified by field experiments in this paper. Adopting the established model, the impact of the horizontal and vertical offsets of the vehicle gravity center on the dynamic contact behavior of the drive gear and the safety and stability of the rack vehicle in the straight section and the ramp section was explored. Results show that when the rack vehicle has a gravity center offset, the gear rack meshing disturbance has a significant impact on the vehicle running characteristics. The wheel-rail force is not only increased or decreased due to the offset of the vehicle gravity center, but also affected by the dynamic meshing of the gears and racks to produce severe vibrations. The lateral offset of the vehicle gravity center has a linear effect on the wheel-rail vertical force and the wheel load reduction rate. When the lateral offset of gravity center reaches 0.3 m, the wheel-rail vertical force reaches 75 kN, and the wheel load reduction rate reaches 0.44. The vertical acceleration of the car body and the stability of the car body are more sensitive to the longitudinal offset of the gravity center of the car. When the center of gravity is set to 2.0 m behind, the vertical acceleration is increased by 1.8 times, and the ramp section is increased by 3.7 times. When the center of gravity is 1 m behind, the stability of the car body is optimal. The conclusions of this study provide theoretical support for the design and safe operation and maintenance of mountain cog railways in China.