Mechanical security locks work according to two fundamental principles: incorporating fixed obstructions to keep the wrong keys out, or using movable pins or tumblers that have to be put in the right positions by the key to move the bolt. The ancient Egyptians invented primitive tumbler locks that held a bolt in place across a door; their tumblers were wooden pegs up to two feet long.
The Old Testament suggests that ancient keys were also very large: “And the key of the house of David will I lay upon his shoulder; so he shall open, and none shall shut; and he shall shut, and none shall open.” (Isaiah 22, xxii) While other civilizations have incorporated brass, bronze, silver, gold, steel, and carbon composites into their locks since those early models, many people in theMiddle East still use the Egyptian wooden model – 4,000 years later!
Even by the Renaissance locks and keys were still cumbersome. According to “History of the Lock” from www.about.com, the Beddington lock, of wrought iron with a gilt rim, “measures about 14 x 8 inches and includes the Royal Arms of the Tudor kings. It is said that Henry VIII took it with him when he traveled and had it screwed to his bedroom door wherever he stayed.”
A great leap forward in lock technology came with Englishman Joseph Bramah’s 1884 patent for a lock whose security mechanism was placed inside an enclosed cylinder. The small key didn’t reach the bolt itself, but instead pushed a set of sliding plates that, in the right positions, caused the bolt to move.
Thirty-four years later the famous Londoner Jeremiah Chubb patented a security lever lock. Levers are thin metal plates that swing on the same pivot and must simultaneously be lifted to pre-selected positions for the key to move the bolt. The lever lock became a standard mechanism for more than 150 years.
The American inventors Linus Yale Sr. and his son, Linus Jr., designed pin-tumbler locks with a completely enclosed mechanism. Rather than using flat levers or plates, their locks use narrow metal pins to move the tumblers. The key is cut to correspond to pins in the bottom of the lock; when turned, the pins push the tumblers into the right position to open the locking mechanism. To make this pin-tumbler cylinder lock work, Linus Yale Jr. replaced the traditional round, fluted key with the flat serrated key we still use today.
Most locksmiths consider Medeco locks the top of the line for pick resistance. Their internal structure includes specially designed pins that must be elevated and rotated to an exact position in order for the lock to operate. Additionally, they have false slots on the sides of the pins, mushroom-shaped top pins, and a reciprocal slider mechanism, to further enhance the cylinder’s pick resistance. To resist drilling, hardened steel inserts are used to protect critical areas of the plug face, shell, and sidebar, and hardened steel rods are also used for the bottom pins and selectively for the top pins.
Even Medeco’s keys are special, with three crosscut angles that can’t be duplicated by a local key-copy place. The keys, protected under patent, trademark, and copyright laws, may be duplicated only by Medeco or by a Medeco authorized sales outlet, and only at your request. This means that you must get duplicates at a Medeco dealer, and records are kept.
Other important developments and inventions in locks since the 1800s include the time lock, in which a standard clock mechanism keeps even the right key from operating until a certain amount of time has elapsed; and the combination lock familiar to anyone who ever took a gym class. But even after 4,000 years, the original Egyptian concept of a bolt with tumblers and pins to move it is still a guiding principal of locksmithing.