Summary : The method of D-partitioning enables us to determine for a linear system the stability limit curves in a plane in which some parameter of the system represents the abscissa and another one the ordinate. Hitherto the method was used for the case that the coefficients of the characteristic equation are linear functions of both of the parameters. By applying it on the case of a single railway vehicle, moving along the track, it is shown that the method is not restricted to such linearities.