| 摘要 |
386,895. Screws. CLAYTON, C. E. EVERY-, 51, Chancery Lane, London.- (Shakeproof Lock Washer Co. ; 2501, North Keeler Avenue, Chicago, U.S.A.) July 19, 1932, No. 20432. Addition to 386,083. [Class 89 (i).] A self-tapping screw according to the parent Specification has the external diameter of the threads at the entering end gradually reduced, the root diameter of these threads being constant throughout. |
