Adjustable spanner

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Image:Adjustable wrench.jpg There are many forms of the adjustable spanner or shifting spanner, from the taper locking spanners which needed a hammer to set the moveable jaw to the size of the nut, to the modern screw adjusted spanner.

There is a class of adjustables that automatically adjust to the size of the nut. The most modern are digital types that use sheets or feelers to set the size, and other simpler models that use a serrated edge to lock the moveable jaw to size.

Some early spanners were invented by Edwin Beard Budding (1795-1846), and Johan Petter Johansson of Sweden in 1892. In addition a type called a monkey wrench is thought to have been patented by one Charles Moncky.

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Proper use

This tool is often misused, causing excess wear or distortion. When the type illustrated is used for heavy loads such as to break loose a nut or bolt, or for final tightening, the movable jaw should always lead the direction of rotation. Failure to do so will cause the movable jaw to become bent and/or loose. (In the illustration the wrench is set up to tighten a right hand thread, using a clockwise motion)

The movable jaw should be snugly adjusted to the nut or bolt head in order to prevent rounding. This type of wrench should never be used on a rounded off nut, as this can overload the movable jaw. Nor should the wrench be used "end on" in cramped quarters, where a socket wrench is more appropriate.

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External links

de:Engländer (Werkzeug) fr:Clef (outils) nl:Bahco pl:Żabka (narzędzie) simple:Adjustable spanner sv:Skiftnyckel fi:Jakoavain

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