Abstract: Paddles are fastened on an inside of a drum casing by fastening elements. The paddles contain a hollow body, which is open in the direction of the drum casing and has a cross-sectional surface area similar to a triangle, and stiffening structures on the insides of its flanks. For secure and permanently stable fastening, in the region of at least some of the structures, strip-shaped installation parts are connected in a form-fitting manner, by way of a section located essentially parallel to the surface of the drum casing, to the inside of the flanks. Moreover, the sections have at least two fastening elements by which the paddle is fastened on the drum casing.