the guide element is associated two securing screws 38 and 39 pass through the respective slots 40 and 41 to fasten the guide element 5 to a non illustrated component of the cleaning machine by loosening the screws 38 39 the guide element 5 may be as a unit radially adjusted relative to the fiber processing roller with which it is associated turning to fig4 in the embodiment shown therein the extruded carrier body 5 is provided with a cylindrical projection 5g receiving a complementally curved hollow cylindrical attachment 9d forming part of the suction chamber 9 this securing arrangement permits the suction chamber 9 to be pivoted for example with manual force for adjustment in the direction of arrows h i turning to fig5 the carrier element 5 has at its downstream end as viewed in the direction of rotation a of the cylinder 3 a projection 5k underneath which the circular recess 5c is situated the cross sectionally generally u shaped guide element 15 has at one end a cylindrical enlargement 15a which is received in the cylindrical opening 5c such that the guide element 15 is pivotally held in the recess 5c for swinging motion as indicated by the arrows j and k thus in order to enlarge the width of the waste discharge opening bounded by the guide element 15 the latter may be pivoted into its dash dot line end position 15 39 in which it is received in a large.