Automobile wheel bearing unit

An automotive vehicle wheel bearing unit comprising:

• a cylindrical external member having an outer flange through which the cylindrical external member is to be attached to a chassis of an automotive vehicle;
• an internal member having a flange at one end thereof to which a wheel of an automotive vehicle is to be attached, said internal member extending within said external member in an axial direction of the unit;
• rolling elements and a cage spacing said rolling elements apart interposed between said cylindrical external member and said internal member, said rolling elements rotatably supporting said internal member relative to said external member;
• a nut secured to the other end of said internal member and mounting the internal member to said external member via said rolling elements;
• a sealing member fixed to said cylindrical external member and covering said nut;
• an annular body extending around said internal member adjacent said nut and fixed relative to said internal member so as to rotate in conjunction therewith, said annular body having a rear surface lying in a plane perpendicular to the axial direction of the unit and facing away from said internal member, and a plurality of projections extending radially along said rear surface and disposed at uniform intervals in the circumferential direction of the annular member;
• and
• rotational detector means for detecting the rotational speed of said annular member, said rotational detector means having a front end and a rear end, and said rotational detector means being fixed to said sealing member at said rear end thereof and extending in the axial direction of the unit between an inner peripheral surface of said sealing member and an outer peripheral surface of said nut, the front end of said rotational detector means confronting a respective location past which location said plurality of projections travel when said annular body is rotated in conjunction with said internal member.