Combination lock

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A Wordlock letter combination lock. 5-digit Wordlock locked with combination Basin and hardened shackle.jpg
A Wordlock letter combination lock.

A combination lock is a type of locking device in which a sequence of symbols, usually numbers, is used to open the lock. The sequence may be entered using a single rotating dial which interacts with several discs or cams, by using a set of several rotating discs with inscribed symbols which directly interact with the locking mechanism, or through an electronic or mechanical keypad. Types range from inexpensive three-digit luggage locks to high-security safes. Unlike ordinary padlocks, combination locks do not use keys.

Contents

Exploded view of the rotating discs. The notches on the disc correspond to the numerals in the correct combination. In this case, the combination is 9-2-4. Combination discs.png
Exploded view of the rotating discs. The notches on the disc correspond to the numerals in the correct combination. In this case, the combination is 9-2-4.
The discs are mounted on one side of the lock, which may in turn be attached to the end of a chain or cable. The other side of the lock, or the other end of the cable, has a pin with several protruding teeth. Combination unlocked.png
The discs are mounted on one side of the lock, which may in turn be attached to the end of a chain or cable. The other side of the lock, or the other end of the cable, has a pin with several protruding teeth.
When the toothed pin is inserted and the discs are rotated to an incorrect combination, the inner faces of the discs block the pin from being extracted. Combination locked.png
When the toothed pin is inserted and the discs are rotated to an incorrect combination, the inner faces of the discs block the pin from being extracted.
A simple combination lock. CombinationLock.jpg
A simple combination lock.

History

The earliest known combination lock was excavated in a Roman period tomb on the Kerameikos, Athens. Attached to a small box, it featured several dials instead of keyholes. [1] In 1206, the Muslim engineer Al-Jazari documented a combination lock in his book al-Ilm Wal-Amal al-Nafi Fi Sina'at al-Hiyal (The Book of Knowledge of Ingenious Mechanical Devices). [2] Muhammad al-Asturlabi (ca. 1200) also made combination locks, two of which are kept in Copenhagen and Boston Museums [3] [ page needed ].

Gerolamo Cardano later described a combination lock in the 16th century.

US Patents regarding combination padlocks by J.B. Gray in 1841 [4] and by J.E. Treat in 1869 [5] describe themselves as improvements, suggesting that such mechanisms were already in use.

Joseph Loch was said to have invented the modern combination lock for Tiffany's Jewelers in New York City, and from the 1870s to the early 1900s made many more improvements in the designs and functions of such locks. [6] However his patent claim states "I do not claim as my invention a tumbler composed of two disks, one working within the other, such not being my invention.", but there is no reference to prior art of this type of lock.

The first commercially viable single-dial combination lock was patented on 1 February 1910 by John Junkunc, owner of American Lock Company. [7]

Types

Multiple-dial locks

One of the simplest types of combination lock, often seen in low-security bicycle locks, briefcases, and suitcases, uses several rotating discs with notches cut into them. The lock is secured by a pin with several teeth on it which hook into the rotating discs. When the notches in the discs align with the teeth on the pin, the lock can be opened.

A single-dial padlock by Master Lock. Masterpadlock.jpg
A single-dial padlock by Master Lock.
The component parts of a Stoplock combination padlock. Stoplock Dismantled.jpg
The component parts of a Stoplock combination padlock.

Single-dial locks

The rotary combination locks found on padlocks, lockers, or safes may use a single dial which interacts with several parallel discs or cams. Customarily, a lock of this type is opened by rotating the dial clockwise to the first numeral, counterclockwise to the second, and so on in an alternating fashion until the last numeral is reached. The cams typically have an indentation or notch, and when the correct permutation is entered, the notches align, allowing the latch to fit into them and open the lock.

The C. L. Gougler Keyless Locks Company manufactured locks for which the combination was a set number of audible clicks to the left and right, allowing them to be unlocked in darkness or by the vision-impaired.[ citation needed ]

In 1978 a combination lock which could be set by the user to a sequence of his own choosing was invented by Andrew Elliot Rae. [8] At this time the electronic keypad was invented and he was unable to get any manufacturers to back his mechanical lock for lockers, luggage, or brief-cases. The silicon chip locks never became popular due to the need for battery power to maintain their integrity. The patent expired and the original mechanical invention was instantly manufactured and sold worldwide mainly for luggage, lockers, and hotel safes. It is now a standard part of the luggage used by travellers.

Other designs

Many doors use combination locks which require the user to enter a numeric sequence on a keypad to gain entry. These special locks usually require the additional use of electronic circuitry, although purely mechanical keypad locks have been available since 1936. [9] [10] [11] The chief advantage of this system is that multiple persons can be granted access without having to supply an expensive physical key to each person. Also, in case the key is compromised, "changing" the lock requires only configuring a new key code and informing the users, which will generally be cheaper and quicker than the same process for traditional key locks.

Electronic combination locks, while generally safe from the attacks on their mechanical counterparts, suffer from their own set of flaws. If the arrangement of numbers is fixed, it is easy to determine the lock sequence by viewing several successful accesses. Similarly, the numbers in the combination (but not the actual sequence) may be determined by which keys show signs of recent use. More advanced electronic locks may scramble the numbers' locations randomly to prevent these attacks.

There is a variation of the traditional dial based combination lock wherein the "secret" is encoded in an electronic microcontroller. These are popular for safe and bank vault doors where tradition tends towards dial locks rather than keys. They allow many valid combinations, one per authorized user, so changing one person's access has no effect on other users. These locks often have auditing features, recording which combination is used at what time for every opening. Power for the lock may be provided by a battery or by a tiny generator set in operation by spinning the dial. [12] [13]

Internal mechanisms

Manufacturers

See also

Related Research Articles

<span class="mw-page-title-main">Rotary dial</span> Component that allows dialing numbers

A rotary dial is a component of a telephone or a telephone switchboard that implements a signaling technology in telecommunications known as pulse dialing. It is used when initiating a telephone call to transmit the destination telephone number to a telephone exchange.

<span class="mw-page-title-main">Pulse dialing</span>

Pulse dialing is a signaling technology in telecommunications in which a direct current local loop circuit is interrupted according to a defined coding system for each signal transmitted, usually a digit. This lends the method the often used name loop disconnect dialing. In the most common variant of pulse dialing, decadic dialing, each of the ten Arabic numerals are encoded in a sequence of up to ten pulses. The most common version decodes the digits 1 through 9, as one to nine pulses, respectively, and the digit 0 as ten pulses. Historically, the most common device to produce such pulse trains is the rotary dial of the telephone, lending the technology another name, rotary dialing.

<span class="mw-page-title-main">Disc tumbler lock</span> Finnish lock design

A disc tumbler or disc detainer lock is a lock composed of slotted rotating detainer discs. The lock was invented by Finnish founder of Abloy, Emil Henriksson (1886–1959) in 1907 and first manufactured under the Abloy brand in 1918.

<span class="mw-page-title-main">Lock and key</span> Mechanical or electronic fastening device

A lock is a mechanical or electronic fastening device that is released by a physical object, by supplying secret information, by a combination thereof, or it may only be able to be opened from one side, such as a door chain.

<span class="mw-page-title-main">Lever tumbler lock</span> Type of lock

A lever tumbler lock is a type of lock that uses a set of levers to prevent the bolt from moving in the lock. In the simplest form of these, lifting the tumbler above a certain height will allow the bolt to slide past.

<span class="mw-page-title-main">Chubb detector lock</span> Type of lever tumbler lock

A Chubb detector lock is a lever tumbler lock with an integral security feature, a re-locking device, which frustrates unauthorised access attempts and indicates to the lock's owner that it has been interfered with. When someone tries to pick the lock or to open it using the wrong key, the lock is designed to jam in a locked state until either a special regulator key or the original key is inserted and turned in a different direction. This alerts the owner to the fact that the lock has been tampered with.

<span class="mw-page-title-main">Safe-cracking</span> Process of opening a safe without either the combination or the key

Safe-cracking is the process of opening a safe without either the combination or the key.

<span class="mw-page-title-main">Rotary combination lock</span>

A rotary combination lock is a lock commonly used to secure safes and as an unkeyed padlock mechanism. This type of locking mechanism consists of a single dial which must be rotated left and right in a certain combination in order to open the lock.

<span class="mw-page-title-main">Padlock</span> Portable locks with a shackle that may be passed through an opening

Padlocks are portable locks usually with a shackle that may be passed through an opening to prevent use, theft, vandalism or harm.

<span class="mw-page-title-main">Latch</span> Mechanical fastener

A latch or catch is a type of mechanical fastener that joins two objects or surfaces while allowing for their regular separation. A latch typically engages another piece of hardware on the other mounting surface. Depending upon the type and design of the latch, this engaged bit of hardware may be known as a keeper or strike.

<span class="mw-page-title-main">Keypad</span> Input device

A keypad is a block or pad of buttons set with an arrangement of digits, symbols, or alphabetical letters. Pads mostly containing numbers and used with computers are numeric keypads. Keypads are found on devices which require mainly numeric input such as calculators, television remotes, push-button telephones, vending machines, ATMs, point of sale terminals, combination locks, safes, and digital door locks. Many devices follow the E.161 standard for their arrangement.

<span class="mw-page-title-main">Electronic lock</span> Locking device which operates by means of electric current

An electronic lock is a locking device which operates by means of electric current. Electric locks are sometimes stand-alone with an electronic control assembly mounted directly to the lock. Electric locks may be connected to an access control system, the advantages of which include: key control, where keys can be added and removed without re-keying the lock cylinder; fine access control, where time and place are factors; and transaction logging, where activity is recorded. Electronic locks can also be remotely monitored and controlled, both to lock and to unlock.

<span class="mw-page-title-main">Luggage lock</span>

A luggage lock is a lock used to prevent luggage from opening by accident, usually with little or no security in mind, although the lock may serve as a deterrent to potential thieves. Luggage locks may be built into luggage or may be external locks such as padlocks or lockable straps.

Master Lock is an American company that develops padlocks, combination locks, safes, and related security products. Now a subsidiary of Fortune Brands Innovations, Master Lock Company LLC was formed in 1921 by locksmith-inventor Harry E. Soref and is headquartered in Oak Creek, Wisconsin. In 1970 the company was purchased by American Brands from Soref's heirs. American Brands was later renamed to Fortune Brands, which then split on October 3, 2011, to create the Fortune Brands Home & Security company and the beverages company Beam Inc..

A keycard lock is a lock operated by a keycard, a flat, rectangular plastic card. The card typically, but not always, has identical dimensions to that of a credit card, that is ID-1 format. The card stores a physical or digital pattern that the door mechanism accepts before disengaging the lock.

<span class="mw-page-title-main">Lock bumping</span> Lock picking technique

Lock bumping is a lock picking technique for opening a pin tumbler lock using a specially crafted bump key, rapping key or 999 key. A bump key must correspond to the target lock in order to function correctly.

<span class="mw-page-title-main">Wordlock</span> Type of combination locks

Wordlock is a brand of combination locks, made by Wordlock, Inc., that differs from traditional combination locks in that it has letters on its dials instead of numbers. This allows the combination to be a four-letter or five-letter word or name, similar to a password, and therefore potentially easier to remember than a series of digits. Wordlocks come in luggage locks, bike locks, padlocks, cable locks and commercial locks.

<span class="mw-page-title-main">Interchangeable core</span>

An interchangeable core or IC is an adaptable locking key cylinder, which can be rapidly exchanged in the field via the use of specialized "control keys".

<span class="mw-page-title-main">Locker</span> Storage compartment

A locker is a small, usually narrow storage compartment. They are commonly found in dedicated cabinets, very often in large numbers, in various public places such as locker rooms, workplaces, schools, transport hubs and the like. They vary in size, purpose, construction, and security.

This is a glossary of locksmithing terms.

References

  1. Hoepfner, Wolfram (1970). "Ein Kombinationsschloss aus dem Kerameikos". Archäologischer Anzeiger. 85 (2): 210–213.
  2. Paul Vallely, How Islamic Inventors Changed the World, The Independent , 11 March 2006.
  3. Hill, D.R. (1998), Studies in Medieval Islamic Technology Ashgate.
  4. Permutation padlock. Found in Google Books.
  5. Improvement in permutation padlocks Google Books.
  6. "IMPROVEMENT IN TUMBLERS FOR PERMUTATION-LOCKS" by Joseph Loch, U.S. patent 200070, 5 February 1878. Found in Google Books.
  7. "US948280.pdf" (PDF). docs.google.com. Retrieved 15 April 2017.
  8. Rae, Andrew E. "Combination lock". Google Patents.
  9. U.S. patent 2,029,080
  10. "Commercial locksmith".
  11. "Thème Serrurerie".
  12. "Kaba-MAS X-09 and CDX-09 High Security Locks" (PDF). December 2010. p. 8.
  13. "Operating Instruction for the X-09 Type 1F High Security Electronic Lock" (PDF). December 2010. Archived from the original (PDF) on 28 July 2011.