35 34 extending towards the abutment 33 when the element 5 assumes the position shown in fig8 i e the twelve o 39 clock position shown in fig7 its left hand free end is withdrawn from the warp thread if now the arm 20 is shifted towards the left in fig8 it displaces the element 5 in the same direction via bearing 31 and ring 30 this movement of element 5 is initially a straight line movement as long as the projection 36 sliding in the groove 35 has not reached the portion 35 39 thereof during this part of its movement the element 5 can advance freely above the plane of the warp 2 just before the projection 36 enters the groove portion 35 39 the element 5 is in the position shown in fig1 in which its free end has passed the effect weft thread 3 so that the latter is in contact with the element 5 during further leftward movement of element 5 in fig8 the projection enters the groove portion 35 39 this causes the ring 30 and with it the element 5 to turn first in counterclockwise direction see arrow f in fig7 in order to clear the raised warp threads 2 39 and then to advance slightly further towards the left as.