Patent ID: 8424664

Claim:
A friction part for a frictionally acting device, comprising: an annular friction surface having an inner edge and an outer edge, with at least one set of rectilinear grooves being provided in the friction surface, said set of grooves having a first groove which defines a radial line extending from the inner edge to a branching point between the inner edge and the outer edge, and second and third groves extending in each case from the branching point to the outer edge, the second groove forming a first angle oriented in one circumferential direction, and the third groove forming a second angle oriented in the opposite circumferential direction; wherein both second and third groove orientation angles are referenced with respect to the radial line to the branching point, the set of grooves being formed in a Y-shape having only three edge-side openings, the first, second and third grooves being merged so as to end at the branching point, a branching angle of less than 180° being formed between the second and third grooves, the branching angle being between 76° and 86°; wherein the orientation angle of the second groove with respect to the radial line equals the orientation angle of the third groove with respect to the radial line, and the second groove and the third groove have in each case one outlet opening, the one outlet opening being arranged in front of the radial line in the one circumferential direction, and the other outlet opening arranged in front of the radial line in the opposite circumferential direction, and the first groove having an inlet opening; and wherein the cross sections of each of the second and third grooves increase in size continuously in the direction of the outlet openings, and the smallest groove cross section of the first groove is larger than the smallest groove cross section of the second groove and is larger than the smallest groove cross section of the third groove.