Apparatus for attaching working elements

In combination, a rotatable fiber-opening roller of a preparatory machine of a spinning mill, said roller being rotatably journalled on opposite ends thereof in longitudinally spaced axle bearing retainers and a longitudinally extending working element attached on spaced inner end surfaces thereof to said axle bearing retainers, by means of respective end caps, said end caps being interposed between end surfaces of said axle bearing retainers and the spaced end surfaces of said working element, with said end caps being one of unitary with said axle retainers and said working element and being fixed in a predetermined position relative to said axle bearing retainers and said working elements being fixed in a predetermined position relative to said end caps, thus assuring exact radial and pivotal location of the working element relative to the fiber-opening roller.