Many publications show that the ride comfort of a railway vehicle can be significantly improved using a semi-active damping control of the lateral secondary dampers. However, the control efficiency depends on the selection of the control algorithm and the damper dynamic behaviour, i.e., its force rise response time, force drop response time and force dynamic range. This paper examines the influence of these parameters of a magnetorheological (MR) damper on the efficiency of S/A control for several control algorithms. One new algorithm has been designed. Hardware-in-the-loop simulation with a real magnetorheological damper has been used to get close to reality. A key finding of this paper is that the highest efficiency of algorithms is not achieved with a minimal damper response time. Furthermore, the force drop response time has been more important than the force rise response time. The Acceleration Driven Damper Linear (ADD-L) algorithm achieves the highest efficiency. A reduction in vibration of 34% was achieved.

It is generally accepted that semi-actively (S/A) controlled dampers can significantly improve the behaviour of a road or rail vehicle. In the case of a railway vehicle, it is possible to increase comfort using S/A control of vertical or lateral secondary dampers. On another way, S/A control offers the possibility of solving a contradiction in the damping requirements for different driving modes, in the case of control of bogie yaw dampers. However, this case has not yet been sufficiently investigated. This paper deals with applying magnetorheological dampers with semi-active control in the locomotive bogie to reduce hunting oscillation. The magnetorheological bogie yaw damper design, new algorithms for its control and application on a complex multi-body locomotive model that simulates fast running on a real straight track are shown. An essential part of the paper focuses on the effect of the damping force level and damper force transient response time. The results have shown that using the semi-active control of the yaw dampers makes it possible to reduce vehicle body lateral oscillation by 60% and improve running stability for higher equivalent conicity and subcritical speed. The critical speed can be increased by more than 250 km/h. The efficiency of the proposed semi-active control increases with increasing damping force level and decreasing transient response time. The control is most effective under conditions of low equivalent conicity.

This paper deals with the lateral force effects of conventional four-axle railway vehicles in conditions of S-shape curves, which are represented especially by switches negotiated in the diverging direction. With the use of a multi-body model of an electric locomotive, a sensitivity analysis of selected vehicle parameters on the maximum guiding force in the S-curve is performed. Subsequently, a definition of so-called equivalent guiding force is proposed. This simplified parameter can be used for the purposes of a quantification of the damaging effects of a vehicle in switches, e.g. in wear-dependent track access charge systems. Attention is also paid to the particularities of systems for active radial bogie or wheelset steering in conditions of tight S-curves and relevant requirements on these systems. The problem of a punctual on-board recognition of the S-curve is demonstrated using experimental data measured on an electric locomotive.

The method currently used for the estimation of train resistance based on specific train resistance has some shortcomings. This method is applied by various railway infrastructure managers, e.g. in the Czech Republic. In this article, first, the Czech formulae for the calculation of train resistance of freight trains are introduced and compared with selected foreign methods. Operational experience from recent years shows that the train resistance formulae used are too conservative and do not correspond to the state-of-the-art railway technology. Therefore, a modified approach for the estimation of train resistance is proposed in this paper. The modification is based on an analysis of run-down tests conducted with ordinary container trains currently operating on the Central European railway network. The contributing factors in the proposed train resistance formula are discussed.

Many publications have shown that semi-actively controlled dampers could significantly improve the behaviour of a road or rail vehicle. In the case of a railway vehicle, these dampers promise to solve the contradiction between the damping requirements of different running modes (fast running on a straight track vs negotiating a tight curve). It is known that semi-active control of a bogie yaw damper can improve the vehicle behaviour when running fast on a straight track, but it is not known whether such semi-active control worsens the vehicle behaviour when negotiating a tight curve. This paper investigates the application of magnetorheological bogie yaw dampers in the locomotive bogie to reduce guiding forces and wear in wheel-rail contact when the vehicle negotiates the S-curve. The paper describes the magnetorheological damper, its mathematical model and the strategies for its semi-active control, followed by the results of simulations on a complex multi-body locomotive model and on-track testing on a real vehicle. The simulations and on-track tests have shown that the use of semi-active control of the yaw dampers reduces the guiding force by about 10%. The reduction in these forces will lead to a reduction in wear in the wheel-rail contact.