In this study, an active steering bogie with a redesigned primary axial rubber spring for urban trains was developed. The applied axial rubber spring had a reasonable stiffness that can be achieved in the X, Y and Z directions. Therefore, the steering performance of the bogie can improve because of the lower longitudinal stiffness. The running performance of an active steering vehicle on a curved track was simulated by means of a co-simulation with VI-Rail and MATLAB/ Simulink. Further, a control algorithm was developed and applied to an actual active steering bogie. The radius of curvature acquired from the actual active steering bogie by the control algorithm was in reasonable agreement with that acquired from a track inspection vehicle. The numerical analysis revealed a significant improvement in the vehicle safety and ride quality and a reduction in the wheel-rail wear and noise. As a result, the validities of the developed primary suspension and control algorithm of the active steering bogie were confirmed. Further, this study may enable railway vehicles to run more stably and faster on sharp curves.

The primary suspension system of a railway vehicle restrains the wheelset and the bogie, which greatly affects the dynamic characteristics of the vehicle depending on the stiffness in each direction. In order to improve the dynamic characteristics, different stiffness in each direction is required. However, designing different stiffness in each direction is difficult in the case of a general suspension device. To address this, in this paper, an optimization technique is applied to design different stiffness in each direction by using a conical rubber spring. The optimization is performed by using target and analysis RMS values. Lastly, the final model is proposed by complementing the shape of the weak part of the model. An actual model is developed and the reliability of the optimization model is proved on the basis of a deviation average of about 7.7% compared to the target stiffness through a static load test. In addition, the stiffness value is applied to a multibody dynamics model to analyze the stability and curve performance. The critical speed of the improved model was 190km/h, which was faster than the maximum speed of 110km/h. In addition, the steering performance is improved by 34% compared with the conventional model.