| 摘要 |
<p>A front sleeve is provided on its outer surface with a tapered portion having a smaller angle of inclination than the tapered portion of the main body and a recessed portion formed centrally in its rear end. A rear sleeve is disposed to the rear of the front sleeve and is provided at its front end with a projecting portion fittable in the recessed portion of the front sleeve. Each of the recessed portion of the front sleeve and the projecting portion of the rear sleeve has a tapered face. The tapered faces extend obliquely straight at the same angle of inclination in longitudinal section. The rear sleeve has a flange engageable with the inner surface of the top wall of the nut. Each of the rear surface of the flange and the top wall surface is in the form of a tapered face, the tapered faces extending obliquely straight at the same angle of inclination in longitudinal section.</p> |
