Bearing unit with retaining cage

A wheel hub assembly for motor vehicles, comprising:

• a hub;
• and
• a bearing unit comprising:
• a radially outer ring provided with respective radially outer raceways;
• at least one radially inner ring provided with respective radially inner raceways;
• at least one row of rolling bodies between the radially outer ring and the radially inner ring;
• and
• at least one cage, wherein the at least one cage comprises:
• a base rib comprising partially spherical concave surfaces;
• a plurality of fingers spaced circumferentially and extending at least from one side of the base rib, said fingers also comprising partially spherical concave surfaces;
• a plurality of partially spherical cavities for holding the rolling bodies, each cavity being defined by the partially spherical concave surfaces of a pair of fingers of the plurality of fingers and of the base rib;
• a radially outer second rib and each cavity of the plurality of cavities is defined by the partially spherical concave surfaces of a pair of fingers of the plurality of fingers, of the base rib and of the second rib;
• wherein the rolling bodies and the cages are in contact with each other via a plurality of protrusions formed on the partially spherical concave surfaces of the fingers and of the base rib, and
• wherein the plurality of protrusions comprise:
• at least one lateral protrusion formed along the surface of each finger of the plurality of fingers of the cage;
• and
• a radially inner central protrusion, centered on the internal lateral surface of the radially inner base rib and a radially outer central protrusion, centered on the internal lateral surface of the second rib.