Re-evaluation of the limitations of the railway wheelset: Passive and active

The fundamental conflict between stability and steering of railway vehicles using the conventional wheelset with a solid axle and coned or profiled wheels may be resolved using various passive suspension arrangements or forms of active control. Various configurations are considered on a strictly comparative basis on the basis of their dynamic response and the corresponding energy dissipation in the wheel-rail contact patch as a basic indication of wear. Though the optimum performance of the wheelset may be achieved on steady-state curves with various forms of steering linkages or yaw relaxation, it is shown that appreciable creep forces, with corresponding energy dissipation, are generated on curve transitions with variable curvature. As a measure of comparison with the above, the application of freely rotating wheels in a passive bogie is also considered. In order to overcome the inherent limitations associated with a passively stabilized solid-axle wheelset, two alternative solutions are considered: first, active stabilization of bogies with conventional wheelsets with reductions in primary yaw stiffness and secondly, active guidance of bogies with independently rotating wheels.