Padlock - Wikipedia, The Free Encyclopedia

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Padlock

An Interchangeable Core Padlock

with customized logo

PadlockFrom Wikipedia, the free encyclopedia

Padlocksare portable locks with

ashackle that may be passed

through an opening (such as a ring,

chainlink, or hasp staple) to

protect property from unauthorized

use, theft, vandalism, or even harm.

Contents

1 History

2 Rating

3 Components

4 Combination locks

5 Padlock icon symbolising

a secure web transaction

6 See also

7 External links

8 References

HistoryPadlocks have been used in China since the late Eastern Han Dynasty

(25220 CE). According to Hong-Sen Yan, director of the National

Science and Technology Museum, early Chinese padlocks were

mainly "key-operated locks with splitting springs, and partially keyless

letter combination locks".[1]Padlocks were made from bronze, brass,

silver, and other materials. The use of bronze was more prevalent for

the earlyChinese padlocks.[1]

There are padlocks dating to the Roman Era, 500 BC 300 AD.[2]They were known in early times by merchants traveling the ancient

trade routes to Asia and China.[3]

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

850 AD.[4]

Smokehouse locks, designed in England, were formed from wrought iron sheet and employed simple lever and

ward mechanisms. 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 key that was threaded into the keyhole. The key 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.
http://en.wikipedia.org/wiki/File:Rusty_Padlock.jpghttp://en.wikipedia.org/wiki/File:Rusty_Padlock.jpghttp://en.wikipedia.org/wiki/Helixhttp://en.wikipedia.org/wiki/Helixhttp://en.wikipedia.org/wiki/Smokehousehttp://en.wikipedia.org/wiki/Key_(lock)http://en.wikipedia.org/wiki/National_Science_and_Technology_Museumhttp://en.wikipedia.org/wiki/File:Rusty_Padlock.jpghttp://en.wikipedia.org/wiki/File:Rusty_Padlock.jpghttp://en.wikipedia.org/wiki/File:Rusty_Padlock.jpghttp://en.wikipedia.org/wiki/File:Rusty_Padlock.jpghttp://en.wikipedia.org/wiki/File:Rusty_Padlock.jpghttp://en.wikipedia.org/wiki/File:Rusty_Padlock.jpghttp://en.wikipedia.org/wiki/Thefthttp://en.wikipedia.org/wiki/Vandalismhttp://en.wikipedia.org/wiki/File:Rusty_Padlock.jpghttp://en.wikipedia.org/wiki/File:Rusty_Padlock.jpghttp://en.wikipedia.org/wiki/Shacklehttp://en.wikipedia.org/wiki/File:Rusty_Padlock.jpghttp://en.wikipedia.org/wiki/Lock_(device)http://en.wikipedia.org/wiki/Key_(lock)http://en.wikipedia.org/wiki/Keywayhttp://en.wikipedia.org/wiki/Helixhttp://en.wikipedia.org/wiki/Wrought_ironhttp://en.wikipedia.org/wiki/Englandhttp://en.wikipedia.org/wiki/Smokehousehttp://en.wikipedia.org/wiki/Key_(lock)http://en.wikipedia.org/wiki/National_Science_and_Technology_Museumhttp://en.wikipedia.org/wiki/Vandalismhttp://en.wikipedia.org/wiki/Thefthttp://en.wikipedia.org/wiki/Propertyhttp://en.wikipedia.org/wiki/Chainhttp://en.wikipedia.org/wiki/Shacklehttp://en.wikipedia.org/wiki/Lock_(device)http://en.wikipedia.org/wiki/File:Best_4B72_Roanoke_Logo_Padlock.jpghttp://en.wikipedia.org/wiki/File:Rusty_Padlock.jpg


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1884 Central Pacific Railroad of Cal.

brass boxcar padlock

Medieval padlock in Kathmandu

Around the middle of the 19th century, "Scandinavian" style locks, or "Polhem locks", invented by the

eponymous Swedish inventor Christopher Polhem, became a more secure alternative to the prevailing

smokehouse and screw locks. These locks had a cast iron 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 company received a patent for these locks in 1871. The

"Scandinavian" design was so successful that JHW Climax & Co. of Newark, New Jersey continued to makethese padlocks until the 1950s. Today, other countries are still manufacturing this style of padlock.

Contemporary with the Scandinavian padlock, 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 thelock body to prevent the lock from getting lost or stolen. Cast heart

locks were very popular with railroads 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 morefragile than the cast hearts, these locks were attractive because they

cost less. In 1908, Adams & Westlake patented a stamped & 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 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 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 orextruded 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.
http://en.wikipedia.org/wiki/Locksmithhttp://en.wikipedia.org/wiki/Machininghttp://en.wikipedia.org/wiki/Linus_Yale,_Jr.http://en.wikipedia.org/w/index.php?title=Yale_%26_Towne&action=edit&redlink=1http://en.wikipedia.org/wiki/Stamping_(metalworking)http://en.wikipedia.org/wiki/Patenthttp://en.wikipedia.org/w/index.php?title=Adams_%26_Westlake&action=edit&redlink=1http://en.wikipedia.org/wiki/Rail_transporthttp://en.wikipedia.org/wiki/Newark,_New_Jerseyhttp://en.wikipedia.org/w/index.php?title=JHW_Climax_%26_Co.&action=edit&redlink=1http://en.wikipedia.org/wiki/McWilliamshttp://en.wikipedia.org/wiki/Cast_ironhttp://en.wikipedia.org/wiki/Christopher_Polhemhttp://en.wikipedia.org/wiki/File:Kathmandu-05.JPGhttp://en.wikipedia.org/wiki/Central_Pacific_Railroadhttp://en.wikipedia.org/wiki/File:Central_Pacific_Railroad_of_Cal_brass_car_lock_1884.jpg


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Viking Age padlock found at Birka.

Early padlock style, on the front gates

of St. Peter's Basilica

Ottoman style handmade padlocks in

Turkey

A high security padlock.

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 off with the first laminated 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.[5]

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 anovel padlock that, with the key inserted, would split lengthwise along

the body in order to create an opening in the shackle. Chicago Lock

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.

RatingForced entry involves the

use of tools such as

hammers, bolt cutters,

chisels, and drills;

consequently, forced entry

attacks exhibit obvious signs of entry. Surreptitious attacks involve

picks, 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 organizations such as ASTM, Sold Secure

(United Kingdom), CEN (Europe), and TNO (The Netherlands).
http://en.wikipedia.org/wiki/Netherlands_Organisation_for_Applied_Scientific_Researchhttp://en.wikipedia.org/wiki/European_Committee_for_Standardizationhttp://en.wikipedia.org/wiki/Sold_Securehttp://en.wikipedia.org/wiki/ASTMhttp://en.wikipedia.org/wiki/Organizationhttp://en.wikipedia.org/wiki/Shim_(engineering)#Lock_pickinghttp://en.wikipedia.org/wiki/Bump_keyhttp://en.wikipedia.org/wiki/Slim_Jim_(lock_pick)http://en.wikipedia.org/wiki/Drillhttp://en.wikipedia.org/wiki/Chiselhttp://en.wikipedia.org/wiki/Bolt_cutterhttp://en.wikipedia.org/wiki/Hammerhttp://en.wikipedia.org/w/index.php?title=Die_cast_locks&action=edit&redlink=1http://en.wikipedia.org/wiki/Chicago_Lockhttp://en.wikipedia.org/w/index.php?title=Wise_Lock_Company&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=Junkunc_Brothers&action=edit&redlink=1http://en.wikipedia.org/wiki/Die-castinghttp://en.wikipedia.org/wiki/Laminatehttp://en.wikipedia.org/wiki/Master_Lockhttp://en.wikipedia.org/w/index.php?title=Harry_Soref&action=edit&redlink=1http://en.wikipedia.org/wiki/File:Bilock.JPGhttp://en.wikipedia.org/wiki/Turkeyhttp://en.wikipedia.org/wiki/File:TurkishHandmadePadlocks.jpghttp://en.wikipedia.org/wiki/St._Peter%27s_Basilicahttp://en.wikipedia.org/wiki/File:Early_padlock.jpghttp://en.wikipedia.org/wiki/Birkahttp://en.wikipedia.org/wiki/Viking_Agehttp://en.wikipedia.org/wiki/File:Viking_Age_lock.png


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Components

A padlock is composed of a body, shackle, 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 (e.g., 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

Main article: Combination lock

Combination padlocks do not use keys. Instead, the lock opens when its wheels are lined up correctly to

display the correct combination.

Padlock icon symbolising a secure web transaction

While executing secure transactions on the web, the submitted information is encrypted using a

Public-key cryptography. Some web browsers display a locked padlock icon while using such a

secure protocol.

See also

Pin tumbler lock

Kent Police Museum Home of the world's largest working padlock.

External links

inventors.about.com (http://inventors.about.com/library/inventors/bllock.htm) History of LocksLock Forums (http://lockforums.com) Discussion on Locks

References
http://en.wikipedia.org/wiki/File:Encrypted.pnghttp://lockforums.com/http://inventors.about.com/library/inventors/bllock.htmhttp://en.wikipedia.org/wiki/Kent_Police_Museumhttp://en.wikipedia.org/wiki/Pin_tumbler_lockhttp://en.wikipedia.org/wiki/Web_browserhttp://en.wikipedia.org/wiki/Public-key_cryptographyhttp://en.wikipedia.org/wiki/HTTP_Securehttp://en.wikipedia.org/wiki/Combinationhttp://en.wikipedia.org/wiki/Combination_lockhttp://en.wikipedia.org/wiki/Shackle


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1. ^ abChi Sung Laih (22 January 2004).Advances in Cryptology: 9th International Conference on the Theory

andApplication of Cryptology and Information Security. Springer. pp. 326329. ISBN 978-3-540-20592-0.

2. ^"Roman padlocks" (http://www.historicallocks.com/en/site/hl/Articles/The-history-of-padlocks/Roman-Era-

500-BC300-AD/). Historicallocks.com. 2008-01-22. Retrieved 2011-11-03.

3. ^"AnIntroduction to the History of Locks" (http://www.locks.ru/germ/informat/schlagehistory.htm).

Locks.ru. Retrieved 2011-11-03.

4. ^"The Ancient Art of the Locksmith" (http://www.buildingconservation.com/articles/locks/locks.htm).

Buildingconservation.com. Retrieved 2011-11-03.

5. ^"Twenty-Two Plates Put In Laminated Lock" (http://books.google.com/books?id=4icDAAAAMBAJ&pg=PA49&dq=Popular+Science+1931+plane&hl=en&ei=GWolTZ3LHcqTnAeEkozrAQ&

sa=X&oi=book_result&ct=result&resnum=3&ved=0CCkQ6AEwAjgy#v=onepage&q&f=true) Popular Science,

March1932, p. 49

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