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The Padlock Patent Archive

Three centuries of keeping things shut

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Tamper-evident lock

Patent drawing sheets showing a cylindrical car door lock with a grooved and cam-projected bolt, a socket with spring dogs mounted on an escutcheon plate, a locking-pin with lugs, and a frangible cast-iron seal fitted over the bolt, illustrated in multiple cross-sectional and elevation views labeled Fig. 1 through Fig. 14.

CAR LOCK AND SEAL.Joseph Chapman · May 31, 1887

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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