| 摘要 |
PURPOSE:To obtain a stable friction torque by radially expanding an upper ball seat by the compression of a lower ball seat by an interference when assembling the ball joint to thrust ridges of a cylindrical wall of the lower ball seat into the outer peripheral surface, and bringing the upper and lower seats into no contact with each other at positions other than the ridges, and stopping the rotation of the upper seat. CONSTITUTION:A plurality of ridges 7 which extend axially are formed on the inner surface of a cylindrical wall 8 of a lower ball seat 4. Upon assembling, since an upper ball seat 9 is axially compressed by an interference (e) of a cylindrical outer peripheral surface 12 of the upper ball seat 9, the upper ball seat 9 is axially compressed and assumes an outer diameter which is larger than the diameter of a phantom cylinder of each ridge 7. Hence, the ridges 7 are thrusted into the outer peripheral surface 12 of the soft upper ball seat 9, and the upper and lower ball seats 9 and 4 assume a state wherein they are unitarily engaged peripherally with each other. Hence, even when a stud 1 rotates, the ball seats 9 and 4 are not rotated in accompaniment with the rotation of the stud 1. The inner diameter of the cylindrical wall 8 is larger than the outer diameter of the upper ball seat 9 after being assembled, the upper and lower ball seats 9 and 4 do not contact each other at positions other than the ridges. |
