Apparatus for separating fibers in open-end spinning machines

In an apparatus for separating fibers in open-end spinning machines, comprising a housing having a cavity, a combing-out cylinder mounted in the cavity and having on its periphery a card clothing by which a fibrous sliver supplied by a feeding device is separated, and means including an insert disposed in the cavity and positionable adjacent the periphery of the combing-out cylinder for defining with said periphery a combing-out zone, the cross-section of a portion of said zone decreasing in the fiber flow direction, the improvement wherein the insert defines, with the adjacent portion of the cylinder periphery, an input portion only of the combing-out zone, and wherein the insert comprises, in combination, at least two peripherally spaced concave operating faces cooperable with the cylinder periphery for providing different combing-out zones therebetween, means for peripherally adjusting said insert into positions in which any desired one of said concave operating faces cooperates with the cylinder periphery to provide the combing-out zone, and means for holding the insert in its adjusted position.