Linus Yale – 1861

Patent 31278

This lock represents Linus Yale Junior’s first foray into improving on his father’s quadruplex and slide locks (Patent 18169). This lock is of particular historical importance to the evolution of the modern day tumbler lock. It represents a pivotal step between Yale Sr.’s slide lock and the current pin tumbler mechanism based on Yale Jr.’s patent 48475 in 1865. This lock introduced a revolving motion. The key maintains the same shape as Yale Sr.’s slide key, but instead of simply sliding it in, it is first inserted and then turned 90 degrees to unlock. This is similar to the modern day lock that probably adorns your house, just with a round key

This particular patent states it was made for a “post-office door lock” or “drawers, closets, cupboards, &c.” and this particular one shown above looks like a standard lower security mortise lock. I have, however, seen a similar lock utilized on a small personal sized safe, and since the mechanism is applicable to safe locks, I have included it in the history of safe locks.

This particular example is unusual in that all the sides are open like a padlock cutaway so the mechanism is visible without removing the front plate. It is likely a factory demonstration model. The lock is numbered 2 on the bolt, only visible with the plate removed. Each piece is also marked with an identifier, for ex. A5, A6. It is quite possible it was made for use in the factory to illustrate to the employees the construction of the lock. Perhaps it was even made by Yale himself, though there is no way to attribute it to him.

Provenance: Ex. Yale employee who purchased the lock when Yale was bought by ABBA