| 摘要 |
541,345. Bolts bolting;; wood-screws OSMOND, G. E. May 22, 1940, No. 9097. Addition to 521,842. [Classes 89 (i) and 89 (ii)] [Also in Groups XXII and XXIII] In making joints as described in the parent Specification the parallel headless screws are tubular in form so that they may serve also as bushes or for the passage of electric conductors &c. The ends may be notched at C to render the screws, self-tapping. The screws may be formed by corrugating thin metal tubing. The screws may be inserted by a tommy bar with a cross pin G to engage notches E or with a screwed end terminating in an abutment shoulder for use with the corrugated screws. |
