Abstract: The present invention concerns a drafting system (30) with a drive (M2) provided with a regulating device (M3, 33) for levelling out mass variations in a fiber mass (6) supplied to the drafting system by a supply source (1). The mass variations are detected by at least one measuring sensor (70) coordinated to the drafting system and the corresponding signals are transmitted to a control unit (S). A further device (11, 12, 62, 63) may be coordinated to the drafting system (30) which is suitable for detecting differences between the delivery speed of the supply source (1) and the intake speed of the drafting system (30) and apply it for influencing the base rotational speed of the drafting system or to detect long term mass variations from a predetermined desired value in which arrangement these mass deviations detected are applied for influencing the base rotational speed of the drafting system.