on the flexible bend 17 and can be displaced parallel to the flexible bend 17 and can be of wedge form construction on the upper side of the carrier element 24 the two curved slideways 20 and 21 of for example anti friction plastics material are arranged in a secure manner side by side in operation the sliding element 14 b ii slides on the sliding contact surface 20 a see fig4 a to 4 c of the slideway 20 and the disc 14 1 of the sliding element 14 b i slides on the sliding contact surface 21 a see fig4 a to 4 c of the slideway 21 because the diameter d 1 of the disc 14 1 is larger than the diameter d 2 of the pin 14 b ii and the distance f is larger than the distance g at the card flat entry the sliding element 14 b i extends over the sliding contact surface 20 a to engage with the sliding contact surface 21 a arranged lower down at the same time the shorter sliding element 14 b ii engages with the sliding contact surface 20 a arranged higher up in this way the opening carding nip of angle u03b2 is formed as the card flat bar 14 iv slides in direction c at the card flat exit the sliding element 14 b having slid beyond the intersection point of the two sliding contact surfaces 20 a.