US Patent 7845856 Gas vent plug, bearing device, and bearing

A gas vent plug is mounted in an aperture communicating with a bearing cavity, and includes a metal annular body, and an elastic tubular body constituted of an elastic member in tube form, integral with the metal annular body, and having a vent at one end face of the tube, protruding outwards in the axial direction of the tube. A circular groove is provided at one end face of the elastic tubular body so as to encircle the vent. Accordingly, variation in the working pressure is eliminated even in the case where the interference is increased when the gas vent plug is mounted in the aperture.