For a bearing mounted between two concentric races rotating relative to each other, and forming an annular gap that accommodates the bearing and is closed by seals, at least one grease tube is provided between the periphery of one of the two races and the annular gap, and is connected to a corresponding grease reservoir. At least one main grease tube opens into the annular gap in an angular sector where an overpressure occurs, a corresponding main grease reservoir is adapted to collect grease flowing from the annular gap through the main grease tube due to the overpressure that may occur within the annular gap in the angular sector.