Abstract: To end or start the spinning operation on an open-end spinning unit by means of a switching device with which the connection to a spinning element or a delivery channel is alternately unblocked and blocked during the reversal of a switching device, the fiber flow is taken out of the region of the particular fiber path to be blocked, and only then is this region blocked. To influence the fiber flow, the volumetric flow rates of suction air flowing through the switching device are controlled. The switching device (6) has at least one closing member (60) with a first orifice (61) which leads to the spinning element (1) and the cross-section of which is enlarged geometrically in a discontinuous manner in the direction of the orifice opening, and with a second orifice which leads into the delivery channel (51) and the cross-section of which is reduced geometrically in a gradual way in the direction of the orifice closure.

Abstract: A method and apparatus for piecing a yarn in a spinning rotor of an open end spinning device is disclosed wherein an increased quantity of fibers is momentarily fed into the spinning rotor after the yarn is returned to the spinning rotor, whereupon the fiber supply is reduced to the normal supply quantity. Preferably, during termination of the spinning process, fibers are stored between a supply device and a fiber opening device which on commencing the piecing process are suddenly released, while at the same time the fiber supply resumes at the normal rate. For effecting the method an abutment surface (110) is preferably provided in a feed channel (11) on the side of a clamping point (15) of a clamping lever (5) for acting on the feed channel (11) facing away from the opening roller (2).