Thread spinning-in apparatus in an open-end spinning machine

The apparatus is designed for returning thread to be spun in, by transferring means to the take-off tube (17) of a spinning unit and for reintroducing it through said tube (17) into the spinning rotor. According to invention, the thread transferring means consists of a guiding duct (16) and a continuing spinning-in duct (16.1) having an air-tight socket (18) to be put on the take-off tube (17) so that, in the spinning-in position, the ducts (16,16.1) form an extension of said tube (17). Thus the end cannot fail to be fed back through the take-off tube 17. Tube 16 has an end 19 for catching the end on bobbin 11. Tube 16, roller 46 for lifting bobbin 11 off its normal drive 9, lever 13 for separating rollers 7,8 and unit 21 for preparing the end to be fed back are all carried on a travelling service unit 1.