<p>The ball joint head (1) is coupled in use to a drive device and comprises: a first spherical body (6) made from steel and formed with a diametral through-hole (7) engaged in use by a first member of the device; a ring (8) in which the first body (6) is forcedly housed but free to rotate; and a second steel body (2) having screw means (3 and 4) for attachment to a second member of the device, and an eye (5) in which the ring (8) is fitted. At least the inner layer of the ring (8) next to the surface of contact with the first body (6) is made of sintered material so as to define pores within the material; these being impregnated with a predetermined lubricant. <IMAGE></p>
