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The Padlock Patent Archive

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Dogs and tumblers

Patent drawing of a round padlock showing its exterior case, an internal cutaway with a hinged hasp secured by pivoting dogs and tumblers, a sliding bolt, and a corresponding notched key.

IMPROVEMENT IN PADLOCKSRosewell Thompson · August 1, 1876

United States patent drawings and specifications are works of the U.S. government and are in the public domain — they were never copyrighted. Download them, print them, frame them. Our commentary and descriptions are © 2026 The Padlock Patent Archive.

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