Since in a braking operation the shortest possible brake distance is required at all times an efficient and robust slip prevention control must be developed. The aim of this paper is to present a control strategy based on an estimation method for the actual wheel-rail friction coefficient. The proposed control procedure does not use measured values of the slip ratio. The estimation method is based on an adaptive observer design. The proposed scheme estimates a set point that prevents wheel-slip and provides a suitable control to maintain the system at the prescribed set point. If external conditions change a new set point is estimated corresponding to the current situation. The control algorithm is tested through simulation examples.