Introducing/removing device of the end in an open-end spinning rotor

Introducing/removing device of the end of the thread for an automatic service trolley for spinning units of open-end spinning machines for carrying out intervention cycles for starting, reattachment and lifting on the spinning units, said trolley carrying on-board members or groups of members dedicated to single or multiple operations of the various cycles, said introducing/removing device (30) comprising a moving structure (31), capable of taking a gripping member into various working positions to take, grip, pull, release and deliver the thread to the various members of the trolley and of the spinning machine, characterised in that its gripping member (32) consists of a pair of parallel rollers (32a, 32b) pressed against each other according to their generatrices, and arranged with their axes substantially perpendicular to the direction of movement of the device (30) and can be moved apart from each other to take and release the thread, said rollers (32a, 32b) being equipped with an actuation motor (34) capable of making the rollers themselves rotate in commanded rotation in the two directions and controlled in angular position and speed, to introduce and re-extract the end of the thread in the opening (9) of the rotor (8).