Frictional part with a zig-zag or undulating circumferential groove in the frictional surface

The present invention relates to a frictional part (2) for a device operating in a frictionally engaged fashion, said part having an annular frictional surface (30) comprising an inner edge (32) and an outer edge (34), wherein a circumferential first groove (40) is provided extending in the frictional surface (30) between radially interior and radially exterior deflection points (44, 42) in a zig-zag or undulating fashion, a plurality of second grooves (54) is provided that originate from the inner edge (32) and extend to the exterior deflection points (42), and a plurality of third grooves (56) is provided that extend from the outer edge (34) into the circumferential first groove (40). According to the invention, the third grooves (56) open at opening points (58) disposed between the deflection points (42, 44) in the circumferential first groove (40).