In this paper an electro-mechanical model for a locomotive is presented. The mechanical part of the model includes the members of transmission from motor rotor to wheels, the weight transfer on locomotive axles and the model of stick-slip phenomenon between rail and wheels. The electrical part of the model consists of a flux oriented induction motor. A new anti slip system is then proposed: the control action is strictly multi-axles and uses only electrical measurements. Moreover it acts with different strategies for temporary or long time slipping phenomena. Simulations have shown that the controlled system is very effective, even if more axles slip.