FILATOIO LUNGO

An assembly of fiber-drawing rollers, used for stretching rovings or fiber bundles in a spinning machine, is divided into a plurality of stages each including an elongate driven roller and a set of coacting counterrollers, the driven rollers being rotated at predetermined relative speeds with the aid of several motors including at least one pair of synchronous motors positively coupled with a drawing roller at opposite ends thereof. These synchronous motors are energized with three-phase current of a frequency determined by the setting of a digitally adjustable frequency selector controlling a solid-state frequency inverter. The selector comprises a frequency divider in the output of a preferably also adjustable source of timing signals which may be a pulse generator driven by a motor coupled with another drawing roller.