groove bottom an apparatus for cleaning the rotor includes a cleaning device having a scraper to be positioned in a predetermined position in the fiber collecting groove of the rotor the scraper automatically assumes an optimal length independently of its abrasion from wear upon entry of the cleaning device into the rotor for assuring a secure placement of the scraper in the bottom of the fiber collecting groove application_number US 41324095 A description in the operation of open end rotor spinning machines it is customary to clean the rotor before restarting a spinning unit in particular the fiber collecting groove of the rotor must be cleaned of any fluff and other soil sticking to it otherwise a proper outcome of spinning cannot be attained maintenance units that patrol in the region of the spinning machines and automatically correct yarn breaks as they occur therefore have a cleaning device by means of which cleaning of the rotor and in particular of its fiber collecting groove is possible referring now to the figures of the drawing in detail and first particularly to fig1 thereof there is seen a cleaning head 5 of such a cleaning device in a sectional view the cleaning head 5 is positioned in front of an opened rotor housing 1 of an open end rotor spinning unit a spinning rotor 2 is disposed inside the rotor housing 1 the spinning rotor 2 is supported by a rotor shaft 3 on a rotor disk bearing in a manner which is known and is therefore not shown in detail herein and the spinning rotor has a fiber collecting groove 4 in the.