Adjustable spanner

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"Adjustable wrench" redirects here. For Michael Torke's composition, see Adjustable Wrench (Torke).
Adjustable spanner
From the bottom: 1. The first adjustable wrench from 1892 (Enköping Mekaniska Verkstad)
2. Adjustable wrench from 1910 with an improved handle (BAHCO)
3. Adjustable wrench from 1914 with a slightly rounder handle (BAHCO)
4. Adjustable wrench from 1954 with improved handle and new jaw angle of 15 degrees (BAHCO)
5. Adjustable wrench from 1984 and the first with ERGO handle (BAHCO)
6. Today's version of the adjustable wrench from 1992 with ERGO (BAHCO)

An adjustable spanner (UK) or adjustable wrench (US) is an open-end wrench with a movable jaw, allowing it to be used with different sizes of fastener head (nut, bolt, etc.) rather than just one fastener size, as with a conventional fixed spanner.[1] Several other names are in use, including the US trademark crescent wrench.[2][3]

Forms and names[edit]

In many European as well as Middle Eastern countries (e.g. France, Germany, Portugal, Spain, Italy, Syria, Lebanon, Turkey, etc.) the adjustable wrench is called an English key.[citation needed] English engineer Richard Clyburn is credited with inventing an adjustable spanner in 1842.[4] Another English engineer, Edwin Beard Budding, is also credited with the invention.[5][6] Improvements followed: on 22 September 1885 Enoch Harris received US patent 326868[7] for his spanner that permitted both the jaw width and the angle of the handles to be adjusted and locked. Other countries, like Denmark, Poland and Israel, refer to it as a Swedish key.[citation needed] Swedish company Bahco attributes the an improved design, in 1891 or 1892, to Swedish inventor Johan Petter Johansson.[8][9] who in 1892 received a patent[10] Johansson's spanner was a further development of Clyburn's original "screw spanner".[citation needed] In some countries (e.g. Czech Republic, Egypt, Greece, Hungary, Serbia, Iran, Slovakia, Slovenia, Poland, Croatia, Romania, and Bulgaria) it is called "French key" (in Poland, "Swedish" or "French" key depending on type).[citation needed] In Canada and the United States, the tool is known as a Crescent wrench or an adjustable wrench.[2][3]

There are many forms of adjustable spanners, from the taper locking spanners which needed a hammer to set the movable jaw to the size of the nut, to the modern screw adjusted spanner. Some adjustable spanners automatically adjust to the size of the nut. Simpler models use a serrated edge to lock the movable jaw to size, while more sophisticated versions are digital types that use sheets or feelers to set the size.

The fixed jaw can withstand bending stress far better than can the movable jaw, because the latter is supported only by the flat surfaces on either side of the guide slot, not the full thickness of the tool. The tool is therefore usually angled so that the movable jaw's area of contact is closer to the body of the tool, which means less bending stress.

Monkey wrenches are another type of adjustable spanner with a long history; the origin of the name is unclear.[11]

The type of straight adjustable spanner with jaws at right angles to the handle shown here as an "English Key"[not in citation given] is mainly called a "King Dick"[not in citation given] spanner in the United Kingdom because of a popular British brand of small, handy and reliable adjustable spanner used throughout the 1900s and used in great numbers during World War II.[12]

In the United States and Canada, the adjustable spanner (adjustable wrench) is colloquially referred to as a "crescent wrench" due to the widespread Crescent brand of adjustable wrenches. The Crescent brand of hand tools is owned and marketed by Apex Tool Group, LLC. In some parts of Europe, adjustable spanners are often called a Bahco.[9] This term refers to the company of the Swedish inventor Johan Petter Johansson, which was originally called B.A. (Bernt August) Hjort & Company. The Swedes themselves call the key "skiftnyckel" which is translated into adjustable key (shifting key).[citation needed]

Proper use[edit]

The movable jaw should be snugly adjusted to the nut or bolt head in order to prevent damage to the fastener's head, or rounding.[citation needed] This type of spanner should not be used on a rounded off nut, as this can overload the movable jaw.[citation needed] Nor should such a wrench be used "end on" in cramped quarters (except perhaps when the nut is barely more than finger-tight), where a socket wrench is more appropriate.[citation needed]

Some cheaper brands' jaws move when twisting on tight nuts.[citation needed]

See also[edit]


  1. ^ FCS Engineering Technology L2. Pearson South Africa. 2009. pp. 161–. ISBN 978-1-77025-592-0. 
  2. ^ a b "crescent wrench", 
  3. ^ a b Bonnier Corporation (October 1999). Popular Science. Bonnier Corporation. pp. 21–. ISSN 0161-7370. 
  4. ^ Murray, John (1845). The Journal of the Royal Agricultural Society of England. pp. 388–. 
  5. ^ John Lloyd; John Mitchinson; James Harkin (30 October 2012). 1,227 QI Facts To Blow Your Socks Off. Faber & Faber. pp. 44–. ISBN 978-0-571-29795-5. 
  6. ^ Lance Day; Ian McNeil (11 September 2002). Biographical Dictionary of the History of Technology. Routledge. pp. 206–. ISBN 978-1-134-65019-4. 
  7. ^
  8. ^ "About Us | BAHCO". Retrieved 2016-11-04. 
  9. ^ a b Swedish Bahco leaflet about the development history of adjustable spanners (including photos) Archived October 15, 2006, at the Wayback Machine.
  10. ^ Andreas Bergh (31 July 2014). Sweden and the Revival of the Capitalist Welfare State. Edward Elgar Publishing. pp. 11–. ISBN 978-1-78347-350-2. 
  11. ^ The Davistown Museum — The Boston Wrench Group
  12. ^ Motor Transport. Iliffe and Sons, Limited. 1908.