| 摘要 |
386,083. Screws. CLAYTON, C. E. EVERY-, 51, Chancery Lane, London.- (Shakeproof Lock Washer Co. ; 2501, North Keeler Avenue, Chicago, U.S.A.) Nov. 17, 1931, No. 31884. [Class 89 (i).] The hardened screw 12 is formed with a slot 24 which decreases in depth as the head is approached. On the insertion of this screw in an unthreaded hole in the work the part 20 of the screw is pressed inwards, thus allowing the then projecting threads on the part 22 to tap the work.
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