Abstract: A rotor to be used in combination with a wheel speed sensor forming part of an anti-lock brake system. The rotor comprises an annular axial central section formed of a magnetic material. First and second annular axial end sections are coaxial and integral with the central section. The first and second annular axial end sections are formed of the magnetic material and arranged such that the annular axial central section is located between the first and second annular axial end sections. A plurality of holes are formed in the annular axial central section. The holes are arranged at equal intervals in the peripheral direction of the annular axial central section. A plurality of first and second depressions are respectively formed in the first and second axial end sections. A pair of the first and each second depressions are respectively located opposite to each other and connected with each hole.

Abstract: An edge prepared with a groove face leaving a vertical root face is combined with another edge prepared with an opposing groove face, a step for receiving a bottom of that edge to be welded thereto, and another step defined by a vertical abutment face for abutting on the root face and a horizontal flat surface, so that a weld groove is continuously defined by the groove faces and the flat surface.