Chain

A chain is a serial assembly of connected pieces, called links, typically made of metal, with an overall character similar to that of a rope in that it is flexible and curved in compression but linear, rigid, and load-bearing in tension. A chain may consist of two or more links. Chains can be classified by their design, which can be dictated by their use:

  • Those designed for lifting, such as when used with a hoist; for pulling; or for securing, such as with a bicycle lock, have links that are torus shaped, which make the chain flexible in two dimensions (the fixed third dimension being a chain's length). Small chains serving as jewellery are a mostly decorative analogue of such types.
  • Those designed for transferring power in machines have links designed to mesh with the teeth of the sprockets of the machine, and are flexible in only one dimension. They are known as roller chains, though there are also non-roller chains such as block chain.
For other uses, see Chain (disambiguation).
A common metal short-link chain
A chain with diamond-shaped metal studs added within its links
Roller chains

Two distinct chains can be connected using a quick link, carabiner, or clevis.

Uses for chain
Links of the American Revolutionary War-era Hudson River Chain as a memorial at West Point

Uses for chain include:

Decoration
  • Jewelry chain, many necklaces and bracelets are made out of small chains of gold and silver
  • Chain of office, collar or heavy gold chain worn as insignia of office or a mark of fealty in medieval Europe and the United Kingdom
  • Decorating clothing, some people wear wallets with chains connected to their belts, or pants decorated with chains
  • Omega chain, a pseudo-chain where the 'links' are mounted on a backing rather than being interlinked

Power transfer
  • Bicycle chain, transfers power from the pedals to the drive-wheel of a bicycle, thus propelling it
  • Chain drive, the main feature that differentiated the safety bicycle
  • Chain gun, type of machine gun that is driven by an external power source, sometimes connected by a chain, to actuate the mechanism rather than using recoil
  • Chain pumps, type of water pump where an endless chain has positioned on it circular discs
  • Chainsaw, portable mechanical, motorized saw using a cutting chain to saw wood
  • Flat chain, form of chain used chiefly in agricultural machinery
  • Ladder chain, a light wire chain used with sprockets for low torque power transmission
  • O-ring chain, a specialized type of roller chain
  • Roller chain, the type of chain most commonly used for transmission of mechanical power on bicycles, motorcycles, and in industrial and agricultural machinery
  • Timing chain, used to transfer rotational position from the crankshaft to the valve and ignition system on an internal combustion engine, typically with a 2:1 speed reduction.

Security and restraint
  • Ball and chain, phrase that can refer to either the actual restraint device that was used to slow down prisoners, or a derogatory description of a person's significant other
  • Belly chain (or "waist chain"), a physical restraint worn by prisoners, consisting of a chain around the prisoner's waist, to which the prisoner's hands are chained or cuffed
    Prisoner in belly chain
  • Bicycle lock (or "Bicycle Chain"), lockable chain
  • Chain boom, large chains used to exclude warships from harbors and rivers
  • Chain link fencing, fencing that utilizes vertical wires that are bent in a zig zag fashion and linked to each other
  • Chain mail, a type of armor consisting of small metal rings linked together in a pattern to form a mesh.
  • Door chain, a type of security chain on a door that makes it possible to open a door from the inside while still making it difficult for someone outside to force their way inside
  • Gang transport chain, a chain used to shackle two or more inmates together for transport or work outside the facility, forming a chain gang
  • Leg iron chains (fetters), an alternative to handcuffs
  • Prisoner transport restraints, a combination which consists of a pair of handcuffs attached by a longer chain to a pair of leg irons
  • Security chain, chain with square edges to prevent cutting with bolt-cutters
  • Chain gun
  • on chain-linked handcuffs the cuffs are held together by a short chain

Traction and pulling
  • Anchor cable, as used by ships and boats, in British nautical usage it is a cable, not a chain
  • Chain steam shipping
  • Chain-linked Lewis, lifting device made from two curved steel legs
  • Curb chain, used on curb bits when riding a horse
  • High-tensile chain (or "Transport chain"), chain with a high tensile strength used for towing or securing loads
  • Jack chain, a toothed chain used to move logs
  • Lead shank (or "Stud chain"), used on horses that are misbehaving
  • Pull switch, an electrical switch operated by a chain
  • Rigid chain actuator, a type of chain that only bends in one direction, allowing it to operate under compression
  • Snow chains, used to improve traction in snow
  • Lavatory chain, the chain attached to the cistern of an old-fashioned W.C. in which the flushing power is obtained by a gravity feed from above-head height. Although most cisterns no longer work like that, the phrase "pull the chain" is still encountered to mean "flush the toilet".

Weapons
  • Chain gun, type of machine gun that is driven by an external power source, sometimes connected by a chain, to actuate the mechanism rather than using recoil
  • Chain-shot, a type of ammunition for a cannon, used to inflict damage to the rigging of a sail vessel in naval warfare
  • Chain weapon, a medieval weapon made of one or more weights attached to a handle with a chain

Other uses

Invention

The metal link chain has been in use since at least 225 BC.[1]

Symbolism

The prevalent modern symbolism is oppression, due to the use for a mechanical restriction of the liberty of a human or animal.

Chains can also symbolize interconnectivity or interdependence. Unicode, in versions 6.x, contains the U+1F517 🔗 LINK SYMBOL, which may show chain link(s). It may also denote a hyperlink.

  • Silent chain
  • Rope chain
  • Twisted link chain
  • Wheat chain
  • Single jack chain
  • Double jack chain
  • Stud link chain
  • Ladder link chain
  • Foxtail chain
  • Singapore chain
  • Rolo chain

See also

References
  1. As early as 225 BC, chain was used to draw a bucket of water up from a well. This very early bucket chain was composed of connected metal rings.Tsubakimoto Chain Co., ed. (1997). The Complete Guide to Chain. Kogyo Chosaki Publishing Co., Ltd. p. 240. ISBN 0-9658932-0-0. p. 211. Retrieved 17 May 2006.


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