The Padlock Patent Archive

Three centuries of keeping things shut

Brass padlock

Patent drawing of a heart-shaped padlock interior mechanism alongside detailed views of a rotating key-hub and matching flat key with a bit-receiving slot.IMPROVEMENT IN PADLOCKSWilliam Wilcox · January 27, 1874Patent drawing of a round padlock showing six figures: the shackle and tumbler mechanism in locked and unlocked states, an exploded view of the lifted mechanism, a front elevation of the assembled lock, an edge view of the case, and a flat sheet-steel key shown from front and edge.IMPROVEMENT IN PADLOCKSFredrick Egge · July 14, 1874Patent drawing of a heart-shaped padlock showing the internal mechanism with a pivoted tumbler, hooked arm, sliding bolt, springs, and a key inserted into the keyhole, alongside separate detail views of the tumbler/pawl assembly and the bolt.IMPROVEMENT IN PADLOCKSJames J. Turner · December 4, 1877Patent drawing showing a padlock's internal cross-latch mechanism, a U-shaped shackle, a warded key, and several small toothed latch pieces labeled with reference letters.IMPROVEMENT IN PADLOCKSWilliam P. Wirth and Theodor Heinrich Wichert · April 22, 1879Patent drawing of a round padlock with a hinged hasp (Fig. 1), two enlarged cross-sections of the internal bolt and key mechanism (Figs. 2 and 3), and a perspective view of the notched key cylinder (Fig. 4).IMPROVEMENT IN PADLOCKSHenry A. Dodge · August 19, 1879Patent drawing sheet showing a round padlock with a curved hasp (B) and casing (A), plus eight numbered figures illustrating the internal sliding plate, pivoted tumbler sections, locking bolt, gears, and a flat key, with inventor's signature and witness signatures at bottom.PADLOCK.Willard D. Doremus · April 28, 1891Patent drawing of a cylindrical permutation padlock showing an exploded barrel with letter-marked rotary tumbler rings, a threaded end cap, a shackle with locking projections, and a key-shaped pull, all labeled with numbered reference lines.PERMUTATION-PADLOCKCharles J. Evans · March 28, 1916