Improvement of Dynamic Performance of Trucks with Longitudinally Unsymmetric Structures by Semi-Active Control for Rail Vehicles

This paper presents dynamic characteristics of unsymmetric suspension trucks with semi-active control to achieve compatibility between high-speed stability and curving performance. According to the direction of vehicle motion, the damping coefficient is switched so that the interwheelset structure, characterized by stiffness and damping, is asymmetric fore-and-aft. It was found in a previous study using a simple calculation model that curving performance is especially enhanced in comparison with conventional symmetric trucks. In this paper, unsteady state curving behavior of the proposed unsymmetric trucks during curve entry is calculated using full car body models with nonlinear wheel profile, considering nonlinear characteristics of the contact force between wheel and rail. Calculation results were compared with those for a conventional symmetric truck. The unsymmetric suspension truck with conical wheel profile has the best curving performance while keeping adequate stability even in sharp curves. The profiled wheel tread has not only superior steering ability but also a possibility to improve high-speed stability.