enlargement 6 into contact with the interior surface of hook 3 the drawing also shows a vertical protection member 11 and a cam member 12 which of course forms part of the loom and not of the gripper in the form of a wedge with beveled surfaces the operation of the device is as follows once the illustrated drawing gripper has penetrated into the corresponding carrying gripper the weft thread f is drawn therefrom by the hook 3 and tends to wedge itself between the profiled end 6 of the oscillating element 4 and the upper inner part of the same hook 3 fig1 5 such parts are of complementary shape and stiffly cooperate with each other to retain the thread f thanks to the combined action of the spring 10 which causes the element 4 to oscillate in the gripping position and of the wedging in effect produced by the stretching undergone by the weft thread with a self clamping action of the parts 3 and 6 the thread f is thus firmly retained by the gripper while the latter travels through the shed as shown in fig1 when the gripper has come out of the shed it meets on its path the freeing member 12 member 12 engages the loop tailpiece 7 of the rear end of element 4 and thanks to its wedge surface causes the oscillation of the bar 5 about its own axis defined by the ends of the bar itself the thread f is freed by the profiled end 6 of the element 4 moving away from the hook 3 as shown in fig2 the gripper according to the invention permits the obtaining of numerous very important advantages to start with the pivoting at the two ends of the oscillating element 4 permits.