 Parts of the magnetic circuit are normally not laminated, which creates delays between excitations and fluxes, but the machines are used in applications where a quick response is not essential.Their predominant use has been in trains, where they are axle-driven, and used to provide lighting and the charging of batteries.An axle-driven generator is subject to variable speeds and changes in the direction of rotation, but the characteristics of the machine allow it to produce useful energy down to very low speeds.