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Expired
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Harry William Smart
Charles Thomas Gann
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Publication of GB190724846ApublicationCriticalpatent/GB190724846A/en
24,846. Smart, H. W., and Gann, C. T. Nov. 9. Bolts ; wood-screws.-To prevent surreptitious removal, a screw-bolt or wood-screw for locks, hinges, brass plates, &c. is formed with an auxiliary head B screwing into the main head. The screw is inserted by means of a stud C or a crossgroove on the auxiliary head. The screw is also applicable when a countersunk head is required for ships, bridges, &c. One auxiliary head may be used for any number of screws, or may form part of the tool used for inserting the screw, which may be used with a ratchet or a hand brace.
GB190724846D1907-11-091907-11-09Improvements in and relating to Screws
ExpiredGB190724846A
(en)
Self-locking screw with socket head - is tightened by engagement of special tool with flap surfaces, on sides of equilateral triangle, with curved surfaces to prevent unscrewing