Adjustable wrench

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. Several other names are in use, including the US trademark crescent wrench.

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. English engineer Richard Clyburn is credited with inventing an adjustable spanner in 1842. Another English engineer, Edwin Beard Budding, is also credited with the invention. Improvements followed: on 22 September 1885 Enoch Harris received US patent 326868 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. Swedish company Bahco attributes the an improved design, in 1891 or 1892, to Swedish inventor Johan Petter Johansson. who in 1892 received a patent Johansson's spanner was a further development of Clyburn's original "screw spanner". 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). In Canada and the United States, the tool is known as a Crescent wrench or an adjustable wrench.

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.

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Wikipedia