not only the rotational speed of the friction spinning drum sections 90 and 91 but also the sub atmospheric pressure or vacuum in their interiors is determinant for imparting the twist to the fibers at the yarn end furthermore the width of the converging space formed by the two pairs of friction drum sections can be made variable and adjustable during build up of the yarn the fibers on the more distant friction spinning drum section 91 form the inner yarn region at a yarn forming position or location 93 the fibers on the closer friction spinning drum section 90 form the outer yarn region at the yarn forming position or location 92 a modification of the apparatus illustrated in fig1 is shown in fig1 in this modification the pair of friction drum sections more distant from the withdrawal rolls 20 and of which in fig1 only the friction spinning drum 91 is shown is upwardly displaced or offset as viewed in the direction of viewing fig1 in an axially parallel manner as a result the yarn portion produced at the associated yarn forming position or location 93 is drawn over the drum edges of which in fig1 only the drum edge 100 of the friction spinning drum section 91 is shown during withdrawal in the yarn withdrawal.