A truncated spherical ball enters a cavity in a link using an entry slot in the link away from the end of the link and axially extending toward the link arm. Passage of the rotated ball through the entry slot is prevented by excess thickness of the ball relative to slot width until the link is expanded by heating. Full bearing surface exists at the end and sides of the link cavity and bearing surfaces are not contacted while forcing a fit. The ball is secure from inadvertent removal.
