Abstract
Abstract The large longitudinal impact of heavy-haul trains is the main factor limiting their development, and the asynchronous nature of train-braking systems is the main cause of this longitudinal impact. In this paper, a segmented electro-pneumatic braking solution fully compatible with the existing freight-train braking system in China is proposed to improve the synchrony of train-braking systems. A simulation model for this braking system is developed based on air-flow theory, the 120 distribution valve and electronic control devices. The braking characteristics obtained from simulations are compared to those from the train-brake testing platform, and show high fidelity. On this basis, the effects of the new braking system on the braking capacity and longitudinal impact of a 20 000 t heavy-haul train are analysed by further simulation. The results show that during service brakes, the segmented electro-pneumatic braking system can increase the braking capacity by 4.2–24.7% and reduce the coupler force by 21.6–68.0%. Therefore, it can be seen that the segmented electro-pneumatic braking system is a new type of electro-pneumatic brake that meets the needs of the Chinese railway network. It solves the problem of the longitudinal impact of heavy-haul trains satisfactorily, and its compatibility with the existing braking system (resulting in a reduced modification workload) makes it possible to maintain normal operations on heavy-haul lines while trains undergo modification.
Highlights
Because of its high efficiency and low cost, the heavy-haul train is widely used in railway freight transportation across the world, especially in the long-distance transportation of bulk goods such as ore and coal
It can be seen that the segmented electro-pneumatic braking system is a new type of electro-pneumatic brake that meets the needs of the Chinese railway network
The airwave propagation speed is about 320 m/s, so a braking system relying on pure air transmission is limited by the speed of air transmission, and it is impossible to solve the problem of longitudinal impact completely by increasing the braking-wave speed in the pneumatic braking system
Summary
Because of its high efficiency and low cost, the heavy-haul train is widely used in railway freight transportation across the world, especially in the long-distance transportation of bulk goods such as ore and coal. Segmented electro-pneumatic braking relies on compressed air and electrical signals to transmit braking signals together, so the braking capacity and synchrony of trains will change greatly; at the same time, its brakingwave propagation law is completely different from that of the pure pneumatic braking system or the ECP system in the United States, as both the braking-system propagation characteristics and the brake-cylinder pressure-variation characteristics will greatly affect the longitudinal impact of the train. This study develops simulation models of train-braking and longitudinal train-dynamics systems, and, based on the characteristics of the new braking system obtained from a stationary testing platform, determines the difference in longitudinal impact via simulation This is of great significance for further improving the design of the segmented electro-pneumatic braking system and guiding the study of longitudinal impact testing
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