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In addition to the discontinuity of the rail profile of a normal turnout, the unique S-shaped curve of a crossover significantly affects the negotiation performance of a train. For heavy-haul freight trains, the in-train forces generated during the braking process may further deteriorate the running safety. Investigating the dynamic behaviour of the train passing through the crossover under braking forces, therefore, can provide a reasonable basis for ensuring train safety. This paper analyses the dynamic response and wheel wear of a three-vehicle train negotiating a single crossover under variable conditions, including variable braking forces, wheel-rail friction coefficient, and crossover layout forms. The results show that the three factors have considerable influences on train safety. If one of the three factors keeps an ideal level, the safe probability of empty wagons can be significantly improved. Considering that there are still some crossovers with tight curves in the existing railway system, avoiding large braking or lubricating the wheel flange in the crossover is still an effective solution to improve the vehicle's performance. In addition, for a new single crossover, a 600-m-radius curve is a good option for balancing permissible train speeds and construction costs of the crossover. [ABSTRACT FROM AUTHOR]

Aiming at preventing frequently occurred coupler jack-knifing in slave control locomotives of 20,000-tonne heavy-haul trains, a theoretical and experimental research on enhancing the coupler stability has been carried out. Field tests are conducted to ascertain the load characteristics of the slave control locomotive, and the coupler stability mechanism of the locomotive is studied. A dynamic simulation model considering the locomotive, adjacent wagons, and attached coupling devices is established and validated. Based on the model, countermeasures for improving the coupler stability are studied. The field test results indicate that: 1) the slave control locomotives suffer from sustained compressive forces less than 1500kN at the braking stage of cycle braking, while the maximum short-term impact force at the release stage exceeds 2000kN; 2) The coupler jack-knifing mostly occurs at the braking stage, and the yaw angles of the middle couplers are larger than the front and rear couplers. According to the theoretical analysis and dynamic simulation results, the coupler stability can be improved by increasing the stiffness of secondary lateral bump stops and reducing its clearance. Moreover, the proposed countermeasure of setting up lateral bump stop to locomotive couplers is proved to be effective to prevent the coupler jack-knifing. [ABSTRACT FROM AUTHOR]