Adjustable spanner

From Wikipedia, the free encyclopedia
Jump to navigation Jump to search
A CAD drawing of an adjustable spanner, Swedish key
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 1915 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, and most other English-speaking countries) or adjustable wrench (US and Canada) 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] The name Crescent wrench is often used in Canada and the United States and is an example of a generic trademark,[2] the name Crescent referring to the Crescent Tool Company which patented the tool design in 1915 in the United States.[3]

Forms and names[edit]

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. Swedish company Bahco attributes an improved design, in 1891 or 1892, to Swedish inventor Johan Petter Johansson[8][9] who in 1892 received a patent.[10][11] In Canada and the United States, the tool is known as a Crescent wrench or an adjustable wrench.[12] In Australia it is referred to as a "shifting spanner", usually abbreviated to "shifter".[13]

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. Still, one should avoid applying excessive force on tight bolts, since doing so can pry open the mounting of the movable jaw causing the wrench to no longer be able to be snugged to bolt heads, loosen too easily, or mar bolt heads. In some cases the jaws of the tool can break.

Monkey wrenches are another type of adjustable spanner with a long history; the origin of the name is unclear.[14]

A popular type of adjustable spanner has a base and jaws that form four sides of a hexagon, and is therefore particularly suited for hexagonal nuts ("hex nuts") and hexagonal headed ("hex head") cap screws and bolts.

In the United States and Canada, the adjustable spanner (adjustable wrench) is synonymous with "Crescent wrench" due to the widespread Crescent brand line of adjustable wrenches;[2] the former Crescent Tool Company was the assignee of the 1915 U.S. patent for the most familiar form factor of adjustable wrench.[3] The Crescent brand of hand tools is now owned and marketed by Apex Tool Group, LLC. In some parts of Europe, adjustable spanners are often called a Bahco.[9][15] This term refers to the company of the Swedish inventor Johan Petter Johansson, which was originally called B.A. (Bernt August) Hjort & Company. In Denmark, this type of spanner is commonly referred to as a "svensknøgle", which basically translates to Swedish key. The Swedes themselves call the key "skiftnyckel", which is translated into adjustable key (shifting key).[16] In Australia, adjustable spanners are also referred to as "shifters".[17]


See also[edit]


  1. ^ FCS Engineering Technology L2. Pearson South Africa. 2009. pp. 161–. ISBN 978-1-77025-592-0.
  2. ^ a b "Has crescent wrench become a generic trademark?". 12 January 2020. Retrieved April 29, 2021.
  3. ^ a b U.S. Patent 1133236A
  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. ^ U.S. Patent 326,868
  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. ^ Johansson, Johan Petter (May 11, 1892). "SE Patent: SE-4,066 Stallbar skrufnyckel". Directory of American Tool and Machinery Patents.
  11. ^ 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.
  12. ^ Bonnier Corporation (October 1999). "Popular Science". The Popular Science Monthly. Bonnier Corporation: 21–. ISSN 0161-7370.
  13. ^ "Shifter". June 2019.
  14. ^ The Davistown Museum — The Boston Wrench Group
  15. ^ "Has bahco become a generic trademark?". 12 January 2020. Retrieved April 29, 2021.
  16. ^ Basic Swedish: A Grammar and Workbook ISBN 1-351-16966-1 p. 177
  17. ^ "shifting spanner". HarperCollins.