The dynamics of a railway wheelset is investigated, focusing on the effect of the contact force models. For large values of creep velocities, the Coulomb model can be used as an asymptotic approximation of wheel-rail contact forces. Then, we get a nonsmooth dynamical system with codimension-2 discontinuities. At the discontinuity of the phase space, the so-called limit directions can be found, which correspond to the possible transitions between slipping and rolling. By this analysis, the nonsmooth model can complement the usual linear creep force model from the opposite direction, and we can explore more details about the qualitative behaviour of the wheelset.