segment of the branch channel 6 returning to the channel 5 the air jet issuing from the blow nozzle 9 ensures that the filling 14 shall reliably rest against the wear resistant element 7 and also against the wear resistant element 11 although the blow nozzle 8 comprises two or more small blow orifices delivering compressed air with well directed jets the blow nozzle 9 comprises only one more substantial blow aperture as shown in particular in fig3 another wear resistant element 10 is mounted in the vicinity of the front edge of the inlet of the branch channel 6 and runs essentially transversely to the direction of insertion a of the filling 14 while forming a first deflection area for the filling 14 the sizing that is the diameter of this element 10 is comparatively small in order that the inlet to the branch channel 6 can be placed as close as possible to the filling insertion conduit 4 the cross section or curvature of the wear resistant element 7 essentially corresponds to that of the branch channel 6 and consequently the yarn rests along a comparatively long path against the wear resistant element 7 in a variation of the shown embodiment the wear resistant elements 7 and 11 as well as the support element 12 are one integral component having a pear or droplet shaped cross section as shown by fig2 a fitting 20 is present at the housing of the device 1 to affix a.