screws 6a a guard 6b carried by the member 6 surrounds but is spaced from the mixing tubes 3 as shown in the drawing the nozzle bodies 2 as seen from the free end of the mixing tube 3 have a somewhat diverging position with respect to each other said position facilitates supplying at 8 the weft yarn from the separate weft yarn supplies cooperating with each of the blowing nozzles said supplies being not further shown in fig1 the nozzle assembly is in a position in which the mixing tube 3 of the upper blowing nozzle 1 is in the operative position relative to the weft transport channel formed by the assembly of the contoured reed lamellae 9 therein the reed 9 is shown in a plane which is rotated through 90 u00b0 with respect to the remainder of the structure the nozzle assembly may be pivoted from the position as shown in fig1 around the axis 5 in the direction of the arrow p to a position in which the mixing tube 3 of the lower blowing nozzle arrives in its operative position with respect to the reed 9 the end pieces of the mixing tubes 3 diverge somewhat as seen in the insert direction so that the outflow ends of both mixing tubes have in their operative position identical positions with respect to the reed for carrying out the pivotal movement around the axis 5 an actuating element 10 is used this actuating element comprises a block 10a enclosing both mixing tubes 3 at a position between the nozzle bodies 2 and the outflow ends of the mixing tubes which block is pivotably connected through a strap 11 extending as shown in the drawing through a space provided between the member 6 and the laterally.