| 摘要 |
<p>The device (2) is assembled of a housing with a locking plate (214) in the shape of a teardrop, a radial positioned locking bolt (222), and a spring supported, axially movable control pin (22). The upper end of the device (2) has the shape of a twin cone and is provided with several axial slots (212a). For use the device (2) is inserted into the lower area (12) of the removable crown (1), a plug element accommodated within the twin-cone area pushed against a matching cavity (13) in the lower surface of the crown (1) and the locking bolt (222) moved into the required position.</p> |
