Abstract: In the combination of a textile yarn spinning machine, a traveling unit movable along the spinning machine for monitoring production of attenuated strands, and supply strand interruption mechanism responsive to the traveling unit, an improvement which comprises a wedge member movable relative to a back roll pair of a drafting unit between a normal running position withdrawn from a nip formed between the rolls and an interruption position of insertion into the nip, together with actuation mechanism mounted above and overlying the corresponding drafting unit.