Draft Gear Characteristic Optimization Research Of High-speed Freight Train

China railway has been widely constructing fast freight transportation to adapt to the rapid development of market economy.To achieve convenience and efficiency of railway freight transportation by opening 160km/h high-speed freight train.With the increasing of running speed of high-speed freight train,this ensures the efficiency of freight transportation.At the same time,it also leads to increase of the acceleration of vehicle and the longitudinal impact of train,which will affect the steady running of train and endanger the transportation safety of high value-added freight.Draft gear is an important device for weakening vehicle impact and vibration,it is necessary to optimize and improve existing draft gear performance for the heavy haul train to adapt to the requirement of high-speed freight transportation.This article uses the air brake system and longitudinal dynamics of train combined simulation system,bases on MT-2 draft gear and takes emergency braking of high-speed freight train as the model.Researching generate mechanism and numerical distribution of the longitudinal impulse of train in the process of emergency braking.Analyzing the influence of different characteristics of draft gear on longitudinal dynamic performance of train by changing local characteristic of draft gear.Optimizing the characteristic of draft gear for high-speed freight train.Verifying the characteristic of draft gear and checking its performance parameters after optimization.The result shows that the maximum in-train force and the maximum acceleration occur in the rear of train length in the process of emergency braking,which is generated by rear vehicles impacting,and their numerical dimension will increase with the increase of initial braking velocity and couple slack.In addition,the characteristic of draft gear optimized by four schemes can reduce the longitudinal impulse of train in the operating condition.And with the extension of optimization range of characteristic curve in the small deflection range,the maximum in-train force will be reduced,the maximum acceleration tends to be stable after being reduced to a certain extent,the capacity and energy absorption rate of draft gear will be reduced.Consequently,the MT-2 draft gear can be considered to improve.Its initial pressure can be designed in 90~120kN.And in the small deflection range of 20 mm or 30 mm,the impedance force increase to 300 kN smoothly to reduce longitudinal impulse in the operating condition.In the large deflection range of 20 mm or 30 mm outside,it can maintain the original characteristics to ensure sufficient capacity for shunting impact.