Lock and key

"Lock and key" redirects here. For the novel by Sarah Dessen, see Lock and Key.

Padlock

Simple three-disc locking mechanism
from a wooden box recovered from
the Swedish ship Vasa, sunk in 1628

A lock is a mechanical or electronic fastening device that is released by a physical object (such as a key, keycard, fingerprint, RFID card, or security token) or secret information (such as a keycode or password), or combination of more than one of these.

Typically, in pin-tumbler and wafer-tumbler applications, a lock in the rest position is closed. The key has a series of grooves on either side of the key (the key's blade), which limit the type of lock the key can slide into. As the key slides into the lock, the grooves on the blade of the key align with the wards in the keyway allowing or denying entry to the cylinder. Then, a series of pointed teeth and notches on the blade called bittings allow pins or wafers to move up and down until they are in line with the shear line of the inner and outer cylinder, allowing the cylinder or cam to rotate freely inside the lock and the lock to open.

History of locks

Medieval lock in Kathmandu

Securing one's property has long been a concern of people throughout the world. Beyond hiding the objects or constantly guarding them the most frequently used option is to secure them with a device. Early solutions included knots to either detect, like the Thief knot, or hamper, like the Gordian Knot. Historians are unsure where the first lock was invented, but evidence suggests that locks initially developed independently in the Egyptian, Greek, and Roman civilizations. Wooden locks and keys were in use as early as 4,000 years ago in Assyria. The first known lock with a key is a pin lock. The lock is strung on a rope hanging out of a hole in a door. A cylinder of wood with a hole drilled through its axis is the key, the length of the cylinder being the critical factor. The key is inserted into the hole and the bolt is pushed the correct distance. To lock the door the rope was pulled to extract the key cylinder, simultaneously pulling the bolt closed. This type of lock is still in use in certain parts of the world. Puerto Rico still uses this system. A disadvantage of this lock is that a vandal can push the rope into the hole — an ancient equivalent of putting glue into a lock.

The warded lock is present from the Antiquity. This lock is still used in modern times when the security required is not high and cost is a significant factor. This lock has become the most recognisable lock/key design in the Western world. Lock puzzles were used to obscure the locking mechanism or even provide a non-functioning lock for the thief to waste time on.

In the early 1900s a wooden pin lock with a wood key was discovered in Egypt and is believed to have been used in 250 b.c.

Early improvements in pin locks included increasing the number of pins to increase security, and changing the orientation of the pins to allow the key to provide the unlocking force instead of a rope, thus establishing the principles of the modern pin tumbler lock.

Famous locksmiths

See also: Locksmithing

Chinese lock and key from Yunnan Province, early 20th century

• Robert Barron patented a double-acting tumbler lock in 1778, the first reasonable improvement in lock security.
• Joseph Bramah patented the safety lock in 1784. It was considered unpickable for 67 years until A.C. Hobbs picked it, taking over 50 hours.
• Jeremiah Chubb patented his detector lock in 1818. It won him the reward offered by the Government for a lock which could not be opened by any but its own key.
• James Sargent described the first successful key-changeable combination lock in 1857. His lock became popular with safe manufacturers and the United States Treasury Department. In 1873, he patented a time lock mechanism, the prototype for those used in contemporary bank vaults.
• Samuel Segal invented the first jemmy-proof locks in 1916.
• Harry Soref founded the Master Lock Company in 1921 and patented an improved padlock in 1924 with a patent lock casing constructed out of laminated steel.
• Linus Yale, Sr. invented a pin tumbler lock in 1848.
• Linus Yale, Jr. improved upon his father's lock in 1861, using a smaller, flat key with serrated edges that is the basis of modern pin-tumbler locks. Yale developed the modern combination lock in 1862.

Types of locks

A type of padlock side view.

Door with two locks, one in the door knob and a separate deadbolt.

A typical combination lock.

Placement of locks depending on door type

Locks at Hohenzollernbrücke in Cologne, Germany

Locks may be entirely mechanical, or electromechanical. They may be operated by turning some form of removable key, by keying or dialling in a combination which directly or via electromechanical means operates the lock, with some form of magnetic or other card reader, or by moving a part on a safety lock intended to prevent accidental operation rather than to prevent unauthorized access.

Warded lock

The warded lock is one of the earliest types of locks. It said to have been developed in China to lock things of value.

Tumbler locks

Pin-tumbler lock

The Pin tumbler lock is the most widespread lock in the western world. Pin-tumbler locks have been around in some form since 2000 BCE. The Egyptian form of this lock was large, heavy, and made of wood, with pins made of metal, usually bronze, but sometimes iron. This design in its modern form was first patented in 1805 in England. The patent holder was an American named A.O. Stansbury. In the middle of the 18th century, the American locksmiths Linus Yale Sr. and his son, Linus Yale Jr., refined the lock design into the form recognizable today. These early versions of the pin-tumbler lock were expensive to produce, and did not become widely available until mass production became feasible. They also lock things.

Wafer-tumbler lock

The first patent for the wafer lock was issued in the United States in 1868 to P.S. Felter. The wafer lock is relatively inexpensive to produce and is often used in automobiles and cabinetry. This type of lock is generally made of die-cast zinc alloy, and also can lock things.

Lever locks

Lever locks were invented in Europe in the 17th century. This is a popular lock type for safes and North American prisons today, as they are generally built of strong materials. They are also used as door locks in some countries. This is the type of lock that replaced the medieval warded lock in the 19th century. Robert Barron of England patented the double-acting lever in 1778. Jeremiah Chubb would follow with his own detector lock in 1818. They can also lock things.

Disc tumbler lock

The disc tumbler lock or Abloy lock was invented in 1907, and is widespread in Finland. The mechanism contains no springs and is durable. Picking the lock is too hard compared to alternative means of gaining entry, keeping things locked. It locks things.

Other types

There are also many other types of lock, such as warded locks, tubular locks, electronic locks (itself a huge area) and also many variations of the various types, such as dimple locks, which are a variation on Yale's original cylinder lock in which the pins interact with the side of the key rather than the edge, "laser track" car locks, which are a variation on wafer locks, and some higher security lever locks also include the types of warding found on warded locks. We don't know, however, if they can lock things.

List of common locks

• Bicycle lock
• Cam lock
• Chamber lock
• Child safety lock
• Combination lock
• Cruciform (or Zeiss) lock
• Cylinder lock
• Deadbolt
• Disc tumbler lock
• Electronic lock
  • Biometric lock
  • Electric strike
  • Magnetic lock
• Keycard lock
• Lever tumbler lock
  • Chubb detector lock
  • Protector lock
• Luggage lock
• Magnetic keyed lock
• Padlock
• Pin tumbler lock
• Police Lock
• RFID
• Rim lock
• Security door locks
• Spring bolt lock or night latch.
• Tubular pin tumbler lock
• Time lock
• Turner lock
• Wafer tumbler lock
• Warded lock

See also

• Bored cylindrical lock and Mortice lock, two different approaches to locking mechanisms
• Exit control lock
• Key relevance
• Lock picking
• Locksmithing
• Physical security
• Rope lock
• Security door chain

References

• Phillips, Bill. (2005). The Complete Book of Locks and Locksmithing. McGraw-Hill. ISBN 0-07-144829-2.
• Pulford, Graham W. (2007). High-Security Mechanical Locks : An Encyclopedic Reference. Elsevier. ISBN 0-7506-8437-2
• Alth, Max (1972). All About Locks and Locksmithing. Penguin. ISBN 0-8015-0151-2
• Robinson, Robert L. (1973). Complete Course in Professional Locksmithing Nelson-Hall. ISBN 0-911012-15-X

External links

• "Historical locks" by Raine Borg and ASSA ABLOY
• "Lock Terminology"