Socket wrench

Socket wrench

A socket wrench, more commonly referred to as a ratchet, is a type of wrench, or tightening tool, that uses separate, removable sockets to fit many different sizes of fittings and fasteners, most commonly nuts and bolts. It generally includes a ratcheting mechanism that allows the nut to be tightened or loosened with a continuous motion, rather than requiring that the wrench be removed and refitted after each turn. Typically, a lever behind the socket switches the wrench between tightening and loosening modes. The sockets attach to the ratchet through a square fitting that locks onto them and come in four common sizes: 1/4 inch, 3/8 inch, 1/2 inch, and 3/4 inch. These different square measures are described as "drives." (Despite being denominated in inches, these are international standards and no metric counterparts exist.) Larger drive sizes such as 3/4 inch, 1 inch, and above are usually reserved for use on fasteners used on larger industrial vehicles, in shipyards, and the like. The sockets themselves come in a full range of inch (SAE) and metric sizes. The two should not be substituted for each other, even if the fit seems "close" - it may destroy the nut or bolt head. The sole exception is the 3/4" and 19mm sockets, which vary by only one twentieth of one millimeter (less than the width of a human hair). The advantage of the socket wrench system is "speed" - it is much faster than a conventional wrench, especially in repetitive bolt-on or bolt-off usage.

The modern socket wrench, with interchangeable sockets, was invented by an American J.J. Richardson, of Woodstock, Vt. The tool was patented through the Scientific American Patent Agency on the 18th of June, 1863. [ [] , U.S. patent 38914 information] The first illustration of the tool appears on pg. 248 of the April 16, 1864 issue of Scientific American. [cite journal|title= Improved Wrench |journal= Scientific American |volume= 10 |issue= 16 |pages= p.248 |publisher= Munn & Co. |location= New York |date= April 16, 1864 |url= |doi= |id= |accessdate= 2008-07-01 ]

ocket types

Sockets come in a variety of types:

6-point vs 12-point

Modern nuts and bolt heads are made with hexagonal gripping surfaces and as such limit the number of positions a wrench can adopt when placed over them. Sockets are produced in 6-point (hexagonal) and 12-point (double-hexagonal) configurations. When working in a confined area with limited turning space, 12-point sockets double the number of starting positions. 6-point sockets, however, offer a better grip on fittings and are less likely to slip and round off the corners with continued use and are generally preferred for damaged nuts and bolts. Simply stated: 12-point sockets are faster, six-point sockets are more secure. The majority of good quality "homeowner" socket sets come with 12-point sockets, which are perfectly adequate for almost all uses. Professional mechanics will generally prefer the 6-points sockets.

8-point sockets are still available from some manufacturers, allowing socket users to adjust square-shaped fittings rather than hexagonal fittings. They were much more easily available some years ago, but square-head bolts and nuts, once common, have become a rarity in modern toolmaking.

hallow vs deep

Sockets are available in various lengths, often divided by manufacturers into two categories of "standard" and "deep." Standard, otherwise known as "shallow" sockets, have a lower profile and allow a user to access nuts in narrow spaces. Deep sockets are useful for turning nuts onto bolts when the bolt extends upwards into the socket (as in the case of many bolted joints), a very typical example being exhaust clamp bolts on an automobile.

Some high-end manufacturers, such as Snap-on or Mac Tools, offer what are called "semi-deep" sockets, designed for cases where marginal depth is desirable.

Impact sockets

High strength fasteners in demanding situations often require the use of an impact wrench or impact driver to deliver the amount of torque required to tighten or loosen them. Standard sockets are made of a strong, but brittle steel, such as chrome vanadium. When used with an impact wrench they can shatter explosively if they break. Impact sockets are made of a weaker, but more malleable steel that will deform and split instead of shattering, such as chrome-moly or chrome molybdenum. These sockets are not chrome-plated, as chrome can chip when used with impact wrenches. Instead, they are made with a coating of black oxide or a plastic coating to prevent corrosion.

Impact sockets can be used with hand-held drive tools; however, users often attach them to pneumatic tools, such as the aforementioned impact wrench, and use compressed air to place and remove fittings. This allows adjustments at greater torques (for both tightening and removal of fittings). Furthermore, it often reduces the effort exerted by the user.


These are some of the common accessories that are used with socket wrenches:
*"Extensions", sometimes called "extender arms", allow access to nuts that are difficult to reach, typically in automotive applications.
*A "breaker bar" is an extended-length handle for socket wrenches that adds extra torque for loosening strongly tightened or frozen fasteners.
*"Universal joints" are two articulated socket joints combined at a right angle, that allow a bend in the turning axis of the wrench. They are used with extensions for turning a bolt or nut at a difficult to access location.
*"Flex handles" are socket wrenches in which the drive head pivots back and forth on the handle, to allow the handle to avoid obstructions when being turned in a cramped space.
*"Adapters" allow sockets of one drive size to be used with wrenches of another drive size. They consist of a male drive fitting of one size attached to a female drive fitting of another size. For example, a 1/4 in. to 3/8 in. adapter allows sockets with 1/4 in. drive holes to attach to 3/8 in. wrenches.


External links

* [ Table of socket and nut sizes]

Wikimedia Foundation. 2010.

Look at other dictionaries:

  • Socket wrench — Socket Sock et, n. [OE. soket, a dim. through OF. fr. L. soccus. See {Sock} a covering for the foot.] 1. An opening into which anything is fitted; any hollow thing or place which receives and holds something else; as, the sockets of the teeth.… …   The Collaborative International Dictionary of English

  • socket wrench — n. a wrench with a cylindrical socket that fits over a nut or bolt of a specific size and shape …   English World dictionary

  • socket wrench — [1] A tool with socket end or a drive tool combined with a socket [2] A socket wrench is made up of a ratchet and a variety of sockets. The ratchet end fits into the sockets. The end is usually one of three common sizes: 0.25 (6.35 mm), 0.375… …   Dictionary of automotive terms

  • socket wrench — wrench with sockets of different sizes that can be changed to fit over nuts or bolts …   English contemporary dictionary

  • socket wrench — noun A type of wrench featuring multiple interchangeable socket heads (each designed to fit a particular size of bolt head or other fastener) which can be attached by a socket arrangement to a ratcheting wrench handle or other driver. Syn:… …   Wiktionary

  • socket wrench — a box wrench with a socket that is an extension of the shank. See illus. under wrench. [1885 90] * * * …   Universalium

  • socket wrench — sock′et wrench n. a box wrench with a socket that is an extension of the shank • Etymology: 1885–90 …   From formal English to slang

  • socket wrench — noun a wrench with a handle onto which sockets of different sizes can be fitted • Hypernyms: ↑wrench, ↑spanner • Part Meronyms: ↑socket * * * noun, pl ⋯ wrenches [count] US : a tool that has a part which fits over the end of a bolt or nut and is… …   Useful english dictionary

  • socket wrench — noun Date: circa 1890 a wrench usually in the form of a bar and removable socket made to fit a bolt or nut …   New Collegiate Dictionary

  • socket wrench — noun a ratchet tool with detachable sockets for tightening and loosening nuts of different sizes …   English new terms dictionary

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