Abstract:In order to study the effect of longitudinal impact on vehicle safety, the dynamic model of draft gear was corrected and the correction model was verified by impact simulation; wheel-rail lateral force and derailment factor of vehicle on curve were calculated in mixed train model and combined train model, and the results was compared to single vehicle system dynamic model. The results indicate that the characteristic curves can be simulated by correction model of draft gear; the performance of curve negotiating and vehicle safety is decreased because of longitudinal impact produced by brake, and the coupler force should be considered while studying the vehicle system dynamics; the results of combined train model is smaller than that of mixed train model because of the constant coupler deflection angle in combined train model; Mixed train model is closer to actual condition because the coupler deflection angle is variable with the train running.