Ball and socket joints with wear indicator

Abstract

A wear indicator for knuckle or swivel joints of the ball and socket type wherein the spherical surfaces in swivelling engagement are urged in bearing engagement by a retainer member accomplishing the double function of holding the ball and the socket in assembly and of applying a pre-load force to the ball to prevent vibration and rattle and to compensate for wear of the bearing surfaces. The wear indicator is in the form of an elongate member attached to the pre-load retainer member at a portion thereof which is progressively movable in the direction of wear of the bearing surfaces of the joint for maintaining the pre-load pressure upon the bearing surfaces. The elongate member which, preferably, takes the form of a grease fitting in lubricated joints or the form of a rod in dry or in lubricated-for-life, projects a predetermined distance from an end of the socket when the joint is new, and retracts at least flush or even with a reference plane, such as the plane of the socket end, when the joint has worn to a degree requiring replacement. Alternatively, the tip of the elongate member projects through an aperture in a closure plate mounted at the end of the socket when the joint is new, and retracts with its tip at least flush with the outer surface of the plate when the wear of the joint is such as to require replacement, thus forming a visual and tactile wear indicator.