Abstract: An electrical machine is suggested, in particular an electrical commutated brushless direct current motor or tacho-alternator with a preferably permanent magnetic excitation and air slot winding, wherein the individual coils of the air slot winding are subdivided into at least two partial coils (14a,b to 21a,b) and are arranged in such a manner that the subsequent partial coils (14,15,16,17,18,19,20,21) encompass the preceding partial coils at both sides from the outside in the circumferential direction uniformlly large induced voltages are obtained when switching the different partial coils in series, so that a high running quietness is obtained in the motor operation and a low fluctuation is assured in the generated voltage in the alternator operation.