The Padlock Patent Archive

Three centuries of keeping things shut

Mail-bag lock

Technical patent drawing showing three cutaway views of a padlock case with spring tumblers and a hidden safety bolt engaging a notched hasp, plus detail views of the bolt, bearings, and a double-bitted key.PADLOCK.George McGregor, Robert Lee, and Thos. G. Clinton · August 26, 1851Patent drawing showing an oval metal lock-and-label sheath (Fig. 1) with a circular padlock mechanism at top labeled 'WASHINGTON,' alongside several other oval and rectangular sheath shells, edge views, and detachable printed city-name labels including BALTIMORE, PHILADELPHIA, NEW YORK, NEW ORLEANS, and FREDERICKSBURG.COMPOUND LOCK AND LABEL-SHEATH.Samuel W. Marsh · April 3, 1860Patent drawing of a heart-shaped padlock shown in three cross-sectional views with shackle up and down, plus separate detail drawings of three tumblers, a bolt, a lever, and a barrel key.IMPROVEMENT IN PADLOCKSConrad Liebrich · August 11, 1863