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A system of taking a tuft of yarn and inserting it into a surface is the subject of International Patent WO 01/79611. Describing the invention, Patent Applicant Tapijtfabriek H. Desseaux BV of Oss, The Netherlands, reveals that a tuft of yarn is cut from a supply and then carried by air through a tube, after which it is delivered to an insertion unit. In each system there are at least two moveable tubes and a knife that can be positioned between them so that the requisite length can be cut from either tube. To avoid the danger of dirt entering the system or operatives being cut, the knife travels around an axis within a closed structure that contains the tufts. The system comprises a guide tube that is coaxial with the tube for a first position, and there is virtually an uninterrupted path between the tubes that lead to a second position leading to the insertion element. By having a movable guide tube it is possible to ensure correct guidance of the tuft too. This is particularly important as the tuft is carried by airflow. The airflow controls the tuft and avoids the need to grip it. As soon as the tuft is sufficiently extended beyond the insertion element it is cut and pressed into the surface. Using aVenturi arrangement ensures that airflow is used most efficiently and also means that tufts are processed more effectively. (TheVenturi effect is a special case of Bernoulli's principle, in the case where fluid or air flows through a tube or pipe with a constriction in it. The fluid must speed up in the restriction, reducing its pressure and producing a partial vacuum via the Bernoulli effect. It is named after Giovanni Battista Venturi 1746-1822), an Italian physicist.) By usingVenturi flow, it is possible to ensure the tufts are not opened during handling and that they do not contact the tube walls between the cutter and the insertion point. A single tuft insertion device comprises a yarn feed through a tube connected to a roll. The tube opens on a side remote from the roll and into a feed-through plane between two opposed wheels that rotate in different directions. A tube is arranged opposite these wheels on a side remote from the feed-through tube. The central axis of the tube lies through the plane. One end of the tube, remote from the wheels, opens into a Venturi device . A tube with a central axis coincides with the central axis of the tube and extends from theVenturi device. The yarn cutter comprises a knife that can rotate around a central axis and is provided on a side of the tube remote from theVenturi device. On a side of the knife and away from the tube is a yarn-clamping device and the yarn-inserting unit. The tuft insertion device includes a yarn feedthrough channel - the central axis of which coincides with the axes I I and 14. The yarn feed channel is terminated at an end-plate . Arranged between the yarn clamp and this endplate is a tuft insertion device that comprises a yarn insertion pin, the yarn feed channel, a guide channel arranged beneath, and an opening in a press-down plate. These can be moved independently of each other in a direction or in the opposite direction by means of bellows that are actuated by compressed air.