yarns by preventing the weft thread grasping members from hitting the same it is moreover appropriate to create in the gripper body 16 a hardened zone cooperating with the elastic lamina 10 for example by applying to said body a hard metal element or in some other way the drawing gripper 2 according to the invention has its head part 6 fig1 and 12 shifted sideways in respect of the rear part 20 connected to the advancement strap 8 on the head part 6 of the gripper are arranged fig1 and 12 weft thread grasping and holding means 4 of the type described in u s pat no 4 040 454 the gripper 2 draws the weft thread from the gripper 1 when as in fig1 to 6 these two members meet and their heads 5 and 6 come up side by side on a single side such means comprise a fixed hook 21 and an oscillating lever 22 whose head wedges into the hook 21 so as to lock therein the weft thread under the action of spring means 23 fig1 to 6 according to the invention the head part 6 of gripper 2 is provided fig1 and 12 with a thread guard 24 comprising a profiled appendix 25 extending substantially parallel to the gripper.