| 摘要 |
641,444. Bolt-hole bushes. KENITRA CO., Ltd. Aug. 5, 1947, No. 21313. [Class 89(i)] [Also in Group XXII] Internal thread linings for railway sleepers of the general form described in Specification 609,485 have the crests 17 of the threads lying in a surface that is slightly conical or trumpet-shaped. Instead of being inserted by a special tool as in Specification 621,984, the lining is inserted by the coach screw itself that is screwed about halfway into the lining prior to insertion into the sleeper. The lining may have a flared mouth to prevent it from going too far into the sleeper, and may have a restriction at its lower end to prevent the coach screw passing too far through. The lining is produced by winding strip on a mandrel having the taper |
