the extension of such tangential arcs depends solely on the positions of the inlet yarn guide 19 and the intermediate yarn guides 23 and 25 relative to the drum 5 when the drum 5 rotates in the direction of the arrow 26 the second intermediate yarn guide 25 is located as shown in fig1 and 2 and the same is true of the yarn portions 11a and 11b when the drum 5 rotates in the opposite direction an alternative second intermediate yarn guide 29 is contemplated as shown in phantom line in fig1 on the opposite side of the inlet yarn guide 19 from the intermediate yarn guide 25 in this case the yarn extends from the yarn guide 19 to the yarn guide 23 and from the latter to the yarn guide 29 in the opposite direction to the one shown from the second intermediate yarn guide 25 or as the case may be from the alternative yarn guide 29 the yarn extends to a third intermediate yarn guide 31 and therefrom to an outlet yarn guide 33 such that this portion of yarn is located out of engagement with the feed drum 5 a second sensor 35 bears against the yarn in the portion extending between the yarn guides 31 and 33 such that any breakage of the yarn is detected by the sensor the third yarn guide 31 is not required if the yarn between the second intermediate yarn guide 25 29 and the outlet yarn guide 33 has to extend of necessity remote from the drum 5 the yarn passes from the outlet yarn guide 33 towards a needle 37 other mechanisms have been omitted from.