The Evolution of the Lock

By Lindsay Tucker | Boston Magazine |

5. Bramah’s Safety Lock   In 1784, Joseph Bramah patented his Safety Lock, the most sophisticated lock of its time and for the next 50 years, the hardest lock to pick. Bramah’s was the first locking mechanism to be set with marked precision, and he used six sheet metal plates, arranged in a circle and engaged by a tiny pipe key. Plates were positioned to the right height by the depth of the cuts in the key. In other words, each plate corresponded with the depth of a specific slot cut in the front end of the key. Upon entry, the key positioned the plates in line with a fixed circular locking plate. The slightest misalignment blocked rotation of the key barrel, making it very tough to crack.


6. The Yale Lock
  Famous in New England as a pioneer in lock making, Linus Yale Sr. patented the “Quadruplex” in 1844. A resurrection of the ingenious Egyptian design, Yale Sr.’s lock increased the number of pins, and change their orientation — essentially, the modern pin tumbler lock so many of us use today. His son Linus Yale Jr., the better known of the Yales, further improved on his father’s innovation and went on to introduce the concept of the Monitor Bank Lock, the principles of which also surive today in the combination padlock. Between them, the pair are perhaps the most recognizable and influential conceptual developers of the modern lock.   

7. The Push-Button  Another important milestone in American lock history occurred in the 1920′s with the arrival of Walter Schlage’s cylindrical push-button system — the lock that now dominates bathroom doors across the nation. The basic concept was simple: when the button in the center of the doorknob was pushed in, the mechanism remained locked. Turn the interior door knob and voilà — an unlocked door. Schlage passed away in 1946, but not before winning the coveted inventor’s "Modern Pioneer Award" for his innovation.

8. The Kwikset SmartKey   Following Yale’s reinvention of the pin tumbler, the fundamentals of the American residential security market changed remarkably little until very recently. It was just in 2007 that Walt Strader’s Kwikset SmartKey, based on the concept of the earlier Rielda lock, began to make a dent in the markets. It’s one of the first popular rekeyable locks, able to be reset to a new key in literally seconds using only the unlocking key and a small piece of metal (the SmartKey). The SmartKey lifts and separates a system of pins and metal wafers, freeing the unlocking key such that a new key can be inserted and the pins and wafers will fall into place for the new system. Mighty convenient if your keys are lost or stolen, or if your ex-boyfriend keeps showing up in your apartment unannounced.