electric locomotives;  critical speed;  Serpentine movement;  Optimize parameters

Taking the locomotive as a whole system, 17 degrees of freedom are used to describe the spatial position of the locomotive in the transverse plane in general. Considering the elastic support of the suspension device of the first series and the damping characteristics of the shock absorber, the mechanical model of serpentine motion of the four-axis bogie vehicle was established, and the differential equations of motion were listed. The eigenvalues obtained by the variable step method are used to study the serpentine motion stability and the critical speed of the locomotive, and the conclusion is that increasing the lateral and longitudinal stiffness and damping of the wheelset can reduce the serpentine motion of the bogie and the car body. Reasonable optimization parameters were obtained, and improvement measures were proposed: the hydraulic shock absorber was changed to an electromagnetic hydraulic shock absorber or a serpentine shock absorber, and the original column spring was replaced by a cone spring.