PIVOT JOINT

摘要

A pivot joint is disclosed comprising a first structure (10,12) having a ball (32,114) retained in a receptacle (30,106), a second structure (14,20,102,104) movable with respect to the first structure and in contact with the ball via a bearing (43,46,126), the contact defining location of a pivot point wherein the bearing is shaped to receive the ball and as the bearing wears, the pivot point is substantially maintained in its defined location. The second structure may be biased (108,110) into contact with the ball. The bearing may comprise two or three bearing surfaces (43A,43B,43C, 46A,46B,126A,126B,126C) which may be sloped at an angle to a line perpendicular to the plane of the bearing surface. A third structure (104), moveable with respect to the first and second structures may be provided. The ball may be retained in the receptacle by contact with the receptacle at two points which can be provided at diametrically opposed points of the ball. Also disclosed is a positioning machine comprising a pivot joint.