Nonlinear investigation of the effect of suspension parameters on the hunting stability of a railway truck

The mathematical model of a single conventional railway truck (bogie) consisting of two wheelsets moving with constant speed on a smooth, level, and tangential track is used to numerically investigate the nonlinear dynamics of the truck. Nonlinearities in the model include the nonlinear wheel-rail profile, the friction-creep characteristics of the wheel-rail contact geometry, and the Coulomb friction element between truck frame and bolster. Single-point and two-point wheel-rail contact scenarios are considered in the model. Sensitivity of the critical hunting velocity to primary and secondary suspension parameters is examined. Results of the lateral stability study indicate that the critical hunting velocity of the truck is most sensitive to the primary longitudinal stiffness. A method involving semi-active control of the primary longitudinal stiffness is developed to raise the critical velocity of hunting. This approach is seen to considerably increase the truck critical hunting velocity