Improving rail vehicle dynamic performance with active suspension

Today, it is difficult to further improve the dynamic performance of rail vehicles with conventional passive suspension. Also, simplified vehicle respectively running gear layouts that significantly could reduce vehicle weights are difficult to realize with modern requirements on passenger vibration comfort and wheel and rail wear. Active suspension is a powerful technology that can improve the vehicle dynamic performance and make simplified vehicle concepts possible. The KTH Railway group has, together with external partners, investigated active suspensions both numerically and experimentally for 15 years. The paper provides a summary of the activities and the most important findings. One major project carried out in close collaboration with the vehicle manufacturer Bombardier and the Swedish Transport Administration was the Green Train project, where a 2-car EMU test bench was used to demonstrate different active technologies. In ongoing projects, a concept of single axle - single suspension running gear is developed with active suspension both for comfort improvement and reduced wheel wear in curves. The results from on-track tests in the Green Train project were so good that the technology is now implemented in commercial trains and the simulation results for the single-axle running gear are very promising.