of the creel 13 as well as compensating for the weight of the bobbin 12 and the creel 13 the belt transmission unit 19 functions without play and without hysteresis to a practical extent in the exemplary embodiment the belt transmission unit 19 includes two belts 21 22 which are wound helically around the drive shaft 23 of the electric motor 20 in opposition to one another such that upon a rotation of the drive shaft 23 one belt winds around the drive shaft 23 while the other belt is unwound from the drive shaft 23 the belts 21 22 should have high tensile strength yet nevertheless should be flexible suitable materials for the belts 21 22 are both metal and plastic an example being belts of aramide fibers or other fiber reinforced plastic the belts 21 22 are preferably steel belts in the illustrated embodiment as best seen in fig2 and 3 the belts 21 22 are secured at their respective ends to the drive shaft 23 by securing means 24 25 and are wound up helically onto the drive shaft 23 with identical pitch midway along the length of the drive shaft 23 the belts 21 22 are secured to the transmission lever 18 at spaced securing points 26 27 located at an angular spacing relative to the rotational axis of the pivot shaft 17 of the creel about which the transmission lever 18 also pivots.