Performance Simulation Of Mt-2Draft Gear

With the development of heavy haul freight cars, more and more problems emer-ged in the use of coupler and draft gear. The high failure rate of coupler and draft gear can increase not only the maintenance workload but also endanger the security and reliability of the train. Therefore, in order to better improve the performance of draft gear, it is necessary to do more in-depth research on the performance paramet-ers of freight car draft gear.The geometric relationships among the displacements of MT-2draft gear’s main parts after its installation are calculated,and its impedance forces formulas are deduced, combined with drop-hammering experimental data, theoretical calculation formulas of its initial pressure with release spring force and that without release spring force are provided. The effect of static friction coefficient and geometric contact angle on initial pressure is discussed. Considering release spring force and different sliding friction coefficients of friction pairs, the impedance forces formulas of four working conditions are deduced. In addition, the relationship between sliding speed of each friction pair and operating speed of MT-2draft gear is deduced based on kinematics. Eventually, an equivalent inversion model for calculating the dynamic friction coefficient is established and function of dynamic friction coefficient is calculated based on this model. The function of dynamic friction coefficient is verified by simulating drop-hammering experiment.The effect of each geometric contact angle on dynamic evaluation indexes of draft gear is discussed within its tolerance. Moreover, the range of maximum stroke, maximum impedance force, capacity and absorption rate under rated impact velocity is respectively calculated according to the tolerance of each geometric contact angle. Finally, the no self-locking conditions of forward stroke and backward stroke and the maximum range of each geometric contact angle is deduced. Under the above conditions, the simulation range of each geometric contact angle is determined, and the effect of each geometric contact angle on four dynamic evaluation indexes is discussed. Finally, the effect of rated impact velocity on the performance of draft gear is studied.Eventually, a theoretical method for calculating initial pressure is provided, and it can be used as an auxiliary reference index when checking and designing draft gear. It’s better to take release spring force into account when accurate initial pressure is required. It is necessary to select appropriate angle value according to the effect of each geometric contact angle on initial pressure. The results show that the equivalent inversion model for calculating the dvnamic friction coefficient is feasible, and the function of dynamic friction coefficient is reasonable. The range of maximum stroke, maximum impedance force, capacity and absorption rate under rated impact velocity is respectively calculated according to the tolerance of each geometric contact angle, and the results accord with the related regulation on the performance of21t axle-load freight car draft gear in the TB/T1961-2006. Studies show that there is no much change in the effect of each geometric contact angle on the performance of draft gear after the expansion of the range. It can be seen that if other conditions do not change, it is very difficult to increase capacity and ensure maximum impedance force, maximum stroke and absorption rate accord with the related regulation on the performance of211axle-load freight car draft gear in the TB/T1961-2006only by changing a certain geometric contact angle. Furthermore, the simulation results suggest that impact velocity has a great effect on the performance of draft gear...