Abstract: An electrical apparatus is disclosed to increase the adhesive load per driving axle and therefore the corresponding permissible tractive and braking forces per driving axle of locomotives and motor-coaches which travel on rails and to contribute directly to the over-all tractive force or braking force of such vehicles. In one configuration the electrical apparatus includes a system of linear inductors for generating travelling magnetic fields in the rails, the inductors including a double sequence of conjugate poles, the lines of force of which pass transversely through the upper flange of the rail. In another configuration, the electrical apparatus includes both a system of linear inductors for generating, in the rails, a magnetic field, travelling or fixed, and a conjugate system of electrical brushes for injecting, in the rails, electrical currents in controlled relationship with the magnetic field.