| 摘要 |
A ball and socket pivot joint includes a housing socket, having upper and lower open ends concentrically disposed about a socket axis, receiving a ball stud including an integral stem extending through the socket lower open end with a lower semi-spherical portion of the ball stud seated on a socket lower bearing seat. The socket upper open end is closed by a pressure member disposed between a housing cap and a pressure plate wherein the pressure plate provides an upper bearing seat for an upper semi-spherical surface of the ball stud. The ball stud lower surface is defined by a pivot center having a first radius of curvature on the socket axis while its upper surface is defined by a variable preload center on the stem axis and having a second radius of curvature a predetermined dimension greater than the first radius of curvature. With the ball joint in a neutral mode the socket and stem axes coincide such that the variable preload center is located on both axes and below the ball stud pivot center. As the ball stud pivots through its full angular travel its upper surface exerts a progressively greater force on the pressure plate causing the pressure member to progressively increase preload on the ball stud. The invention provides less preload and angular torque during middle range movement while obviating unseating of the ball stud during extreme angular movement with consequent high preload resisting high angular torque.
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