Effect of Coupler Position Errors on Dynamic Performance of Heavy Haul Locomotive

Several geometric parameters of the locomotive underframes are measured to determine the lateral deviation between the center lines of the car body underframe and the coupler box, and then to reveal the effect of the lateral deviation on the dynamic performance of the heavy haul locomotives under braking conditions. The measurements indicate that the amplitude of the lateral deviation is distributed within the range about 5-10 mm. According to the measured result and the structural features of the coupler/draft gear system which is commonly used in China, a dynamic model for the coupler/draft gear system is established considering the time-varying contact characteristic between the arc surfaces of coupler tail and the front follower. Furthermore, a train dynamic model composed of 2 eight-axes locomotives is established, based on which, the coupler angle, the transverse displacements of car body, and the running safety of the locomotives were calculated under different lateral deviation distances. The results show that under the test conditions in the enterprise, the coupler angle will be larger and the running safety will be deteriorated under braking when the coupler box center lines deviate more from the car body underframe center line. In order to ensure the running safety of train, the deviation distance should be no more than 9 mm.