spinnboxes and rotors arranged in them in which each spinnbox comprises among other things a cover arranged on a front side of the particular associated rotor at least one limitation device for limiting the rotor movement in the direction of the longitudinal axis of the rotor onto the cover is provided which limitation device covers a circular segment of a possible circular contact area between rotor and cover application_number US 24545705 A description reference is now made to the embodiments of the invention one or more examples of which are illustrated in the drawings each embodiment is provided by way of explanation of the invention and is not meant as a limitation of the invention for examples features illustrated or described as part of one embodiment may be used with another embodiment to yield still a further embodiment fig1 shows a cover 1 designed in accordance with the invention together with a rotor 2 in an axial sectional view rotor 2 shown on the left side is only shown by its head for the sake of better clarity since a representing of the shaft can be dispensed with for explaining the present invention rotor cover 1 is designed as a cast part designed on the rotor side with plate shaped recess 3 cover 1 forms a component of a spinning chamber that surrounds the rotor and is not shown in more detail the representation chows cover 1 in a position closing the spinnbox in order to open the spinnbox cover 1.