This part of the UNE 18-172 standard specifies the measurements of smooth radial contact joint ball joints, of the dimensional series E and G. These measurements define the ball joints geometrically, without establishing any restriction regarding materials or methods of construction. manufacturing. The established chamfer measurements are minimum values. The corresponding maximum values are given in the UNE 18-132 standard for bearings. The tolerances on the diameter of the hole, the external diameter and the width are given in the UNE 18-173 standard.