Abstract: A tapered roller bearing has a rib ring against which the large ends of the tapered rollers for the bearing bear to prevent those rollers from being expelled from the annular space between the tapered raceways. The rib ring includes a porous, yet rigid, core and a jacket which covers the exposed surfaces of the core, except along an abutment face at which the large end faces of the rollers contact the rib ring. Here the pores of the core are exposed. The core at one of its other faces has a groove and the jacket has a port that opens into the groove. Pressurized oil is directed through the port and into the groove, from which it flows through the pores of the core and emerges at the abutment surface where it reduces friction between the abutment surface and the roller end faces.