Padlock
Overview
 
Padlocks are portable locks
Lock (device)
A lock is a mechanical or electronic fastening device that is released by a physical object or secret information , or combination of more than one of these....

 used to protect against theft
Theft
In common usage, theft is the illegal taking of another person's property without that person's permission or consent. The word is also used as an informal shorthand term for some crimes against property, such as burglary, embezzlement, larceny, looting, robbery, shoplifting and fraud...

, vandalism
Vandalism
Vandalism is the behaviour attributed originally to the Vandals, by the Romans, in respect of culture: ruthless destruction or spoiling of anything beautiful or venerable...

, sabotage
Sabotage
Sabotage is a deliberate action aimed at weakening another entity through subversion, obstruction, disruption, or destruction. In a workplace setting, sabotage is the conscious withdrawal of efficiency generally directed at causing some change in workplace conditions. One who engages in sabotage is...

, unauthorized use, and harm. They are designed to protect against some degree of forced and surreptitious entry.
The first padlocks were "convenient" locks so they could be carried and used where necessary.

The earliest positive evidence of padlocks comes from the Roman Era, 500 BC–300 AD.

They were known in early times by merchants traveling the ancient trade routes to Asia and China.
Discussions
Encyclopedia
Padlocks are portable locks
Lock (device)
A lock is a mechanical or electronic fastening device that is released by a physical object or secret information , or combination of more than one of these....

 used to protect against theft
Theft
In common usage, theft is the illegal taking of another person's property without that person's permission or consent. The word is also used as an informal shorthand term for some crimes against property, such as burglary, embezzlement, larceny, looting, robbery, shoplifting and fraud...

, vandalism
Vandalism
Vandalism is the behaviour attributed originally to the Vandals, by the Romans, in respect of culture: ruthless destruction or spoiling of anything beautiful or venerable...

, sabotage
Sabotage
Sabotage is a deliberate action aimed at weakening another entity through subversion, obstruction, disruption, or destruction. In a workplace setting, sabotage is the conscious withdrawal of efficiency generally directed at causing some change in workplace conditions. One who engages in sabotage is...

, unauthorized use, and harm. They are designed to protect against some degree of forced and surreptitious entry.

History

The first padlocks were "convenient" locks so they could be carried and used where necessary.

The earliest positive evidence of padlocks comes from the Roman Era, 500 BC–300 AD.

They were known in early times by merchants traveling the ancient trade routes to Asia and China. Evidence may yet be found that predates the Roman era.

Padlocks with spring tine mechanisms have been found in York, England at the Jorvik Viking settlement - dated 850 AD.

The earliest padlocks used in the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

, sometimes called smokehouse
Smokehouse
A smokehouse is a building where meat or fish is cured with smoke. The finished product might be stored in the building, sometimes for a year or more.-History:...

 locks, were formed from wrought iron
Wrought iron
thumb|The [[Eiffel tower]] is constructed from [[puddle iron]], a form of wrought ironWrought iron is an iron alloy with a very low carbon...

 sheet and employed simple lever and ward mechanisms. The design was brought over from England
England
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...

. These locks afforded little protection against forced and surreptitious entry. Contemporary with the smokehouse padlocks and originating in the Slavic areas of Europe, “screw key” padlocks opened with a helical
Helix
A helix is a type of smooth space curve, i.e. a curve in three-dimensional space. It has the property that the tangent line at any point makes a constant angle with a fixed line called the axis. Examples of helixes are coil springs and the handrails of spiral staircases. A "filled-in" helix – for...

 key that was threaded into the keyhole
Keyway
A keyway is the shaped channel in a lock cylinder into which the key slides to gain access to the lock tumblers. Lock keyway shapes vary widely with lock manufacturer, and many manufacturers have a number of unique profiles requiring a specifically milled key blank to engage the lock's...

. The key
Key (lock)
A key is an instrument that is used to operate a lock. A typical key consists of two parts: the blade, which slides into the keyway of the lock and distinguishes between different keys, and the bow, which is left protruding so that torque can be applied by the user. The blade is usually intended to...

 pulled the locking bolt open against a strong spring. Padlocks that offered more key variance were the demise of the screw lock. Improved manufacturing methods allowed the manufacture of better padlocks that put an end to the Smokehouse around 1910.

Around the middle of the 19th century, “Scandinavian” style locks were introduced in America and became a more secure alternative to the prevailing smokehouse and screw locks. These locks had a cast iron
Cast iron
Cast iron is derived from pig iron, and while it usually refers to gray iron, it also identifies a large group of ferrous alloys which solidify with a eutectic. The color of a fractured surface can be used to identify an alloy. White cast iron is named after its white surface when fractured, due...

 body that was loaded with a stack of rotating disks. Each disk had a central cutout to allow the key to pass through them and two notches cut out on the edge of the disc. When locked, the discs passed through cut-outs on the shackle. The key rotated each disk until the notches, placed along the edge of each tumbler in different places, lined up with the shackle, allowing the shackle to slide out of the body. The McWilliams
McWilliams
McWilliams is a surname that refers to:*Alfred McWilliams , Canadian politician from Prince Edward Island*Bill McWilliams , American professional baseball player...

 company received a patent for these locks in 1871. The “Scandinavian” design was so successful that JHW Climax & Co. of Newark, New Jersey
Newark, New Jersey
Newark is the largest city in the American state of New Jersey, and the seat of Essex County. As of the 2010 United States Census, Newark had a population of 277,140, maintaining its status as the largest municipality in New Jersey. It is the 68th largest city in the U.S...

 continued to make these padlocks until the 1950s. Today, other countries are still manufacturing this style of padlock.

Contemporary with the Scandinavian padlock ("Polhem locks"
Christopher Polhem
Christopher Polhammar , better known as , which he took after his ennoblement, was a Swedish scientist, inventor and industrialist. He made significant contributions to the economic and industrial development of Sweden, particularly mining.-Biography:Polhem was born on the island of Gotland...

) were the “cast heart” locks, so called because of their shape. A significantly stronger lock than the smokehouse and much more resistant to corrosion than the Scandinavian, the hearts had a lock body sand cast from brass or bronze and a more secure lever mechanism. Heart locks had two prominent characteristics: one was a spring-loaded cover that pivoted over the keyhole to keep dirt and insects out of the lock that was called a “drop”. The other was a point formed at the bottom of the lock so a chain could be attached to the lock body to prevent the lock from getting lost or stolen. Cast heart locks were very popular with railroads
Rail transport
Rail transport is a means of conveyance of passengers and goods by way of wheeled vehicles running on rail tracks. In contrast to road transport, where vehicles merely run on a prepared surface, rail vehicles are also directionally guided by the tracks they run on...

 for locking switches and cars because of their economical cost and excellent ability to open reliably in dirty, moist, and frozen environments.

Around the 1870s, lock makers realized they could successfully package the same locking mechanism found in cast heart locks into a more economical steel or brass shell instead of having to cast a thick metal body. These lock shells were stamped out of flat metal stock, filled with lever tumblers, and then riveted together. Although more fragile than the cast hearts, these locks were attractive because they cost less. In 1908, Adams & Westlake patent
Patent
A patent is a form of intellectual property. It consists of a set of exclusive rights granted by a sovereign state to an inventor or their assignee for a limited period of time in exchange for the public disclosure of an invention....

ed a stamped
Stamping (metalworking)
Stamping includes a variety of sheet-metal forming manufacturing processes, such as punching using a machine press or stamping press, blanking, embossing, bending, flanging, and coining. This could be a single stage operation where every stroke of the press produce the desired form on the sheet...

 & riveted switch lock that was so economical that many railroads stopped using the popular cast hearts and went with this new stamped shell lock body design. Many lock manufacturers made this very popular style of lock.

In 1877 Yale & Towne was granted a patent for a padlock that housed a stack of levers and had a shackle that swung away when unlocked. It was a notable design because the levers were sub-assembled into a “cartridge” that could be slid into a cast brass body shell. The assembly would remain together by means of two taper pins passed through the shell and cartridge. This design gave the commercial padlock market a serviceable, rekeyable padlock. About twenty years later Yale
Linus Yale, Jr.
Linus Yale, Jr. was an American mechanical engineer and manufacturer, best known for his inventions of locks, especially the cylinder lock. His locks are still widely distributed in today’s society, and constitute a majority of personal locks and safes. Linus Yale, Jr. was born in Salisbury, NY....

 made another “cartridge” style padlock that employed their famous pin tumbler mechanism and a shackle that slid out of the body instead of swinging away.

Although machining metal
Machining
Conventional machining is a form of subtractive manufacturing, in which a collection of material-working processes utilizing power-driven machine tools, such as saws, lathes, milling machines, and drill presses, are used with a sharp cutting tool to physical remove material to achieve a desired...

 was a method that was available to lock makers since the early 19th century, it was not economically feasible to do so until the very early 20th century when electrical generation and distribution became widespread. Some of the earliest padlocks (c. 1905) that were made from a machined block of cast or extruded metal resemble today’s modern padlock. Corbin and Eagle were one of the first lock makers to machine a solid block of metal and insert a relatively new pin tumbler mechanism and a sliding shackle into the holes machined into the body. This style of padlock was both strong and easy to manufacture. Many machined body padlocks were designed to be disassembled so that locksmiths could easily fit the locks to a certain key. The machined body padlocks are still very popular today. The process of machining allows many modern padlocks to have a “shroud” covering the shackle, which is an extension of the body around the shackle to protect the shackle from getting sheared or cut.

In the early 1920s, Harry Soref started Master Lock
Master Lock
Master Lock is an American company primarily known for developing and manufacturing padlocks, combination locks and related security products. Now an operating unit of Fortune Brands Home & Security, Inc., Master Lock Company LLC was formed in 1921 by locksmith-inventor Harry Soref, and is...

 off with the first laminate
Laminate
A laminate is a material that can be constructed by uniting two or more layers of material together. The process of creating a laminate is lamination, which in common parlance refers to the placing of something between layers of plastic and gluing them with heat and/or pressure, usually with an...

d padlock. Plates that were punched from sheet metal were stacked and assembled. Holes that were formed in the middle of the plates made room to accommodate the locking mechanism. The entire stack of plates, loaded with the lock parts in it, was riveted together. This padlock was popular for its low cost and an impact-resistant laminated plate design. Today, many lock makers copy this very efficient and successful design.

Die-casting became popular in the early 1930s among lock makers. Not only was it a very inexpensive way to make padlocks, but it allowed designers to design padlocks with a broad range of geometrical features and ornate designs that sand casting and machining wouldn’t allow. Some lock makers, like Junkunc Brothers, augmented their machined solid body padlock products with the less expensive and more attractive die-cast bodied padlocks. The Wise Lock Company embraced this new medium in making a novel padlock that, with the key inserted, would split lengthwise along the body in order to create an opening in the shackle. Chicago Lock
Chicago Lock
Chicago Lock Co. is a lock manufacturer, founded in Chicago in 1920. Since 1933, it has sold a tubular lock marketed under the registered trademark "Ace." Millions of Ace locks have been sold; for instance, these locks are used in Northwestern Corporation's Triple Play bulk vending...

 pioneered their new “double bitted wafer” and “ACE” products by installing them into a die cast body. With the advent of inexpensive machining done overseas and the overall poor perception of the security of die cast locks, they no longer dominate today’s padlock market.

Rating

Forced entry involves the use of tools such as hammer
Hammer
A hammer is a tool meant to deliver an impact to an object. The most common uses are for driving nails, fitting parts, forging metal and breaking up objects. Hammers are often designed for a specific purpose, and vary widely in their shape and structure. The usual features are a handle and a head,...

s, bolt cutters, chisel
Chisel
A chisel is a tool with a characteristically shaped cutting edge of blade on its end, for carving or cutting a hard material such as wood, stone, or metal. The handle and blade of some types of chisel are made of metal or wood with a sharp edge in it.In use, the chisel is forced into the material...

s, and drill
Drill
A drill or drill motor is a tool fitted with a cutting tool attachment or driving tool attachment, usually a drill bit or driver bit, used for drilling holes in various materials or fastening various materials together with the use of fasteners. The attachment is gripped by a chuck at one end of...

s; consequently, forced entry attacks exhibit obvious signs of entry. Surreptitious attacks involve picks
Slim Jim (lock pick)
A slim jim is a thin strip of metal roughly 60 cm long and about 2–4 cm wide originally marketed under that name by HPC Inc., a manufacturer and supplier of specialty locksmithing tools. Slim Jims are used to unlock automobile doors without use of a key or lock pick...

, bump keys, shims, unauthorized key duplication, and other bypass techniques that, when employed, do not show obvious signs of compromise.

A quantitative measure of a padlock’s resistance to forced and surreptitious entry can be determined with tests developed by organization
Organization
An organization is a social group which distributes tasks for a collective goal. The word itself is derived from the Greek word organon, itself derived from the better-known word ergon - as we know `organ` - and it means a compartment for a particular job.There are a variety of legal types of...

s such as ASTM, Sold Secure (United Kingdom), CEN
European Committee for Standardization
The European Committee for Standardization or Comité Européen de Normalisation , is a non-profit organisation whose mission is to foster the European economy in global trading, the welfare of European citizens and the environment by providing an efficient infrastructure to interested parties for...

 (Europe), and TNO
Netherlands Organisation for Applied Scientific Research
Nederlandse Organisatie voor Toegepast Natuurwetenschappelijk Onderzoek or TNO is a not-for-profit organization in the Netherlands that focuses on applied science. The main office of TNO is located in Delft...

 (The Netherlands).

Components

A padlock is composed of a body, shackle
Shackle
A shackle, also known as a gyve, is a U-shaped piece of metal secured with a clevis pin or bolt across the opening, or a hinged metal loop secured with a quick-release locking pin mechanism...

, and a locking mechanism. The typical shackle is a “U” shaped loop of metal (round or square in cross-section) that encompasses what is being secured by the padlock (i.e., chain link or hasp). Generally, most padlock shackles either swing away (typical of older padlocks) or slide out of the padlock body when in the unlocked position. Unusually designed padlocks may include a straight, circular, or flexible (cable) shackles. Some shackles split apart and come together to lock and unlock.

There are two basic types of padlock locking mechanisms: integrated & modular. Integrated locking mechanisms directly engage the padlock’s shackle with the tumblers. Examples of integrated locking mechanisms are rotating disks (found in "Scandinavian" style padlocks where a disk rotated by the key enters a notch cut into the shackle to block it from moving) or lever tumblers (where a portion of the bolt that secures the shackle enters the tumblers when the correct key is turned in the lock). Padlocks with integrated locking mechanisms are characterized by a design that does not allow disassembly of the padlock. They are usually older than padlocks with modular mechanisms and often require the use of a key to lock.

The more modern modular locking mechanisms, however, do not directly employ the tumblers to lock the shackle. Instead, they have a plug within the “cylinder” that, with the correct key, turns and allows a mechanism, referred to as a “locking dog” (such as the ball bearings found in American Lock Company padlocks) to retract from notches cut into the shackle. Padlocks with modular locking mechanisms can often be taken apart to change the tumblers or to service the lock. Modular locking mechanism cylinders frequently employ pin, wafer, and disk tumblers. Padlocks with modular mechanisms are usually automatic, or self-locking (that is, the key is not required to lock the padlock)

Combination locks

Combination padlocks do not use keys. Instead, the lock opens when its wheels are lined up correctly to display the correct combination
Combination
In mathematics a combination is a way of selecting several things out of a larger group, where order does not matter. In smaller cases it is possible to count the number of combinations...

.

Padlock icon symbolising a secure web transaction


While executing secure transactions on the web, the submitted information is encoded using a public cipher key
Public-key cryptography
Public-key cryptography refers to a cryptographic system requiring two separate keys, one to lock or encrypt the plaintext, and one to unlock or decrypt the cyphertext. Neither key will do both functions. One of these keys is published or public and the other is kept private...

 of the receiving node. Some web browser
Web browser
A web browser is a software application for retrieving, presenting, and traversing information resources on the World Wide Web. An information resource is identified by a Uniform Resource Identifier and may be a web page, image, video, or other piece of content...

s display a locked padlock icon while using such a secure protocol.

See also

  • Pin tumbler lock
    Pin tumbler lock
    The pin tumbler lock is a lock mechanism that uses pins of varying lengths to prevent the lock from opening without the correct key...

  • Kent Police Museum
    Kent Police Museum
    The Kent Police Museum is located within the Chatham Dockyard, in the English county of Kent. It is situated close by the Commissioner's House. The museum is staffed by volunteers, and is open from February through to November....

    Home of the world's largest working padlock.

External links

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
x
OK