bars 14 have at opposite ends spaced from one another parallel to the cylinder axis m a flat bar head 14 a from which extend two steel pins 14 b adapted to glide on the convex upper surface 20 a of the slide guide 20 in the direction of the arrow c the underface of each flat bar 14 carries a flat bar clothing 18 the circle circumscribed on the flat bar clothings 18 is designated at 21 the carding cylinder 4 has along its circumference a cylinder clothing 4 a such as a sawtooth clothing the circle circumscribed about the cylinder clothing 4 a is designated at 22 the clearance between the circles 21 and 22 is designated at d and amounts to for example 0 20 mm the clearance between the convex upper surface 20 a of the slide guide 20 and the circle 22 is designated at e the convex upper surface 20 a has a radius r 1 and the circle 22 has a radius r 2 the radii r 1 and r 2 intersect in the rotary axis m of the carding cylinder 4 fig3 a 3 b and 3 c show to an exaggerated extent for better understanding the change of the distances between the clothings 18 of the flat bars 14 and the clothing 4 a of the carding cylinder 4 fig3 a shows the initial.