the pressure line 49 which is connected to a ring line 51 is opened the ring line 51 applies excess pressure to a large number of workstations 4 the compressed air from the ring line 51 flows through the pressure lines 48 and 49 into the squeezing valve 47 and closes the pressure line 30 the rotor housing 21 no longer has negative pressure applied as the yarn end 16 is generally drawn out of the spinning box because of the high winding speed after the yarn break the yarn end 16 has to be found on the cross wound bobbin 18 lifted from the bobbin drive roller and some layers have to be unwound therefrom once the yarn end 16 has been prepared for the following piecing and a pieceable fiber tuft has been produced on the yarn end 16 the yarn end 16 has to be introduced counter to the normal withdrawal direction through the yarn withdrawal tube 37 and the withdrawal nozzle 26 in the direction of the spinning rotor 23 once the control mechanism of the workstation 4 has been activated by means of a switching element not shown the magnetic valve 50 receives the signal for closing thereupon the squeezing valve 47 opens and the pressure in the pressure line 48 reduces the rotor housing again has the necessary negative pressure for spinning applied at the same time the fiber band feed cylinder 43 is driven and.