the sley being derived from the main drive shaft 39 the shaft 19 of the flywheel 15 is driven through a bevel gear pair 40 while for the reciprocating motion of the sley 10 there is provided in a known manner a reciprocating structure 41 which carries the sley 10 and is linked to the loom frame at 42 the reciprocating structure 41 carries the eyelets 43 for guiding the carrier and on the opposite side a cam following roller 44 arranged to engage a cam 45 such an engagement is ensured by a spring 46 the ratios of the various gears and the angular arrangement of the cams 30 and 45 are such as to produce one stroke of the sley after each throw after the carrier has crossed the shed the numeral 47 denotes the heddles of conventional design and 48 the beam taking up the cloth 49 the carrier 3 before being thrown is centrifuged in the structure 13 by means of the flywheel 15 and pawl 20 the door 23 being closed thus the carrier acquires the necessary throw off velocity which had been reduced during the preceding cycle at a suitable instant as allowed by the stop 28 the door 23 opens under the action of the cam 30 and the carrier starts along the linear throwing portion 17 emerging at a very high speed from the structure 13 facing the latter there is a weft thread 8 suction drawn by the vacuum nozzle 38 and arranged in the very path of the carrier which then catches the weft thread in its movement.