| 摘要 |
<p>The ball (12) is housed in a socket formed by the cylindrical housing (18) and a seat (52) supported by wedges (42, 46) which are mounted on the shaft (44). One wedge (46) slides freely on the shaft but the other (42) has a screw thread to suit the shaft thread (40). When the shaft is rotated by a handle (58), the two wedges are forced together and push the seat against the ball. The ball is in turn pushed against the internally chamfered edge (32) of the flange formed at the upper end of the cylindrical housing. The combined mechanical advantage of the screw thread and the wedges provide a very high locking force.</p> |
