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R ailway freight vehicles that are run with full payload on long downhill slopes with many tight curves must be braked more or less continuously. The in¯uence of braking on the curving performance of iron ore freight cars equipped with different types of three-piece bogie designs and pneumatically actuated single-block tread brakes run on curved track in a downhill slope is investigated. The focus is put on the change in performance in terms of self-steering ability, track forces and expected wear in contacts between wheels and rails. M odelling and simulation of the strongly non-linear dynamic interaction between vehicle and track in braked conditions are performed. The large in¯uence of wheel/rail pro®le matching and the quite different responses to braking for the studied vehicles are shown.

The pantograph-catenary system is a critical component for trains required to run at higher speeds. The pantograph often includes nonlinear characteristics and the scope of this work is to investigate if nonlinear dynamic phenomena can occur in an existing design. A model of a pantograph suspension subsystem has been developed according to physical parameter values of the head suspension of the Schunk WBL88/X2 pantograph, providing electric power to the Swedish high-speed train X2. Studies of the system response for different force excitation show both harmonic, subharmonic and chaotic behaviour for the investigated parameter regions.