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The Padlock Patent Archive

Three centuries of keeping things shut

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Hasp-free chain fastener

Patent drawing of a round combination padlock with a chain looped through two side holes, a dial and knob on top, and internal cutaway views revealing nested permutation rings and a locking bolt.

IMPROVEMENT IN COMBINATION-PADLOCKS.Herbert M. King and S. Dermott Pierce · February 26, 1878

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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