b 18 c in the region of the extraction chambers 18 a 18 b 18 c there are arranged as described below with reference to fig3 a 3 b guide elements 19 a 19 b and 19 c respectively the separating blades 17 a 17 b and 17 c and the extraction hoods 18 a 18 b and 18 c are each arranged on a respective displaceable support 20 a 20 b and 20 c see fig3 a 3 b showing blade 17 a and hood 18 a arranged on support 20 a referring to fig2 a cleaning device which is arranged in a closed housing is supplied with the fibre material to be cleaned arrow h which is especially cotton in flock form this is effected for example by a filling chute not shown by a conveyor belt or the like the lap is supplied by means of two feed rollers 32 33 under the clamping action of a pinned roller 23 having pins 23 a which is rotatably mounted in the housing and rotates anticlockwise downstream of the pinned roller 23 there is arranged a clothed roller 24 which is covered with sawtooth clothing 24 a the roller 23 has a circumferential speed of about from 10 to 21 m sec the roller 24 has a circumferential speed of about from 15 to 25 m sec the direction of rotation.