Clutch plate

Abstract

On a frictional engage surface of one of inner and outer clutch plates constructing a wet-type multi-disk clutch, a plurality of convex ridges are formed at an infinitesimal predetermined interval distance. Lubricating oil is kept between the convex ridges, so that the wedge operation in oil can be reduced, whereby the torque transfer characteristic can be improved. Further, a height of the convex ridge is set equal to or more than 1 .mu.m and the interval distance of the convex ridge is set equal to or less than 600 .mu.m, preferably. In the configuration of the clutch plate, it is made of steel as a substrate. Further, a nitrogen diffusion layer, a nitrided layer and an oxidation tunic is formed on said nitrided layer are formed on the substrate in its order therefrom.

Dependencies are inferred from the claim text.