Keywords: wheel-rail friction coefficient, tribometer, friction modifiers, vehicle dynamics, multibody simulations, wheel-rail interaction, wear.

The level of adhesion between the wheel and the rail, particularly under curving conditions, plays a crucial role in determining the vehicle dynamic behaviour and the wear of the wheel and the rail profiles. Therefore, one of the main objectives of infrastructure owners and train operators is to actively manage adhesion conditions, ensuring safe railway operations while minimizing maintenance costs for both rolling stock and infrastructure. This study investigates the influence of the friction coefficient on vehicle running behaviour and wheel-rail wear under curving conditions. Friction coefficient measurements with a portable tribometer are carried out on a curved section to assess the effectiveness of a track-side lubrication system for flange contact lubrication. Dry and lubricated track conditions are tested, with friction measurements on both the top of the rail and on the gauge face. Test results also show a reduced friction coefficient at the rail gauge face even before activation of the lubrication system, attributable to lubricant deposited by the wheels of trains equipped with onboard flange lubrication systems. The results of friction measurements are used as a reference for vehicle dynamics simulations which are carried out to assess the impact of friction modifiers on curving behaviour and wear. The use of friction modifiers is found to slightly increase the angle of attack and the lateral forces on the leading wheelset, resulting in a reduction in bogie self-steering capability, while still ensuring a significant decrease in wheel–rail profile wear.

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