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A wrench (also called a spanner) is a tool used to provide grip and mechanical advantage in applying torque to turn objects—usually rotary fasteners, such as nuts and bolts—or keep them from turning. In Commonwealth English (excluding Canada), ''spanner'' is the standard term. The most common shapes are called ''open-ended spanner'' and ''ring spanner''. The term ''wrench'' is generally used for tools that turn non-fastening devices (e.g. tap wrench and pipe wrench), or may be used for a monkey wrench - an adjustable spanner.〔(【引用サイトリンク】url=http://www.askoxford.com/concise_oed/wrench?view=uk )〕 In North American English, ''wrench'' is the standard term. The most common shapes are called ''open-end wrench'' and ''box-end wrench''. In American English, ''spanner'' refers to a specialised wrench with a series of pins or tabs around the circumference. (These pins or tabs fit into the holes or notches cut into the object to be turned.) In American commerce, such a wrench may be called a ''spanner wrench'' to distinguish it from the British sense of ''spanner''. Higher quality wrenches are typically made from chromium-vanadium alloy tool steels and are often drop-forged. They are frequently chrome-plated to resist corrosion and for ease of cleaning. Hinged tools, such as pliers or tongs, are not generally considered wrenches in English, but exceptions are the plumber wrench (pipe wrench in British English) and Mole wrench (sometimes Mole grips in British English). ==History== Wrenches and applications using wrenches or devices that needed wrenches, such as pipe clamps and suits of armor, have been noted by historians as far back as the 15th century.〔Henry C. Mercer, Ancient Carpenters' Tools: Illustrated and Explained, Together with the Implements of the Lumberman, Joiner and Cabinet-Maker, 1928, reprint Courier Corporation - 2013, pages 271-272〕 Adjustable coach wrenches for the odd-sized nuts of wagon wheels were manufactured in England and exported to North America in the late eighteenth and early nineteenth centuries. The mid 19th century began to see patented wrenches which used a screw to narrowing or widening the jaws, including patented monkey wrenches. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Wrench」の詳細全文を読む スポンサード リンク
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