Distinguishing Characteristics

• The classic monkey wrench hand tool is an F-shaped slender wrench with two horizontal smooth jaws. The upper jaw is fixed while the lower jaw can be moved up or down with a knurled screw contained in the handle. It has a handle long enough for applying torque to the object to be turned. Monkey wrenches came in a variety of sizes to suit different jobs, and toolboxes usually include a small and large wrench.
  
  

Naming Story

• One favorite legend for how the monkey wrench got its name is that the wrench was invented by Baltimore, Maryland, mechanic Charles Moncky in 1858, and the tool was named after him. In time, Moncky's name got turned into monkey. But there is evidence this wrench was actually a 19th century refinement of an 18th century carriage wrench, and the name came because the jaws vaguely resembled the face of a monkey. However it was named, the monkey wrench is a versatile tool that can get into places where ratchets and socket wrenches can't fit. Although better adjustable wrenches have come into general use, the old monkey wrench still finds occasional use with mechanics, plumbers, farmers and carpenters dealing with old nonstandard square nuts and bolts that they may encounter.
  
  

Agent of Disruption

• The monkey wrench is not just a tool but also a symbol of disruption. The phrase "throw a monkey wrench into the works" refers to action by a person or thing that prevents successful completion of a plan, schedule or project. The phrase also may be used to mean sabotage, especially when carried out as a form of protest. A verb form of the phrase is "He monkeywrenched our plans," and a noun form is "He was convicted of the monkeywrenching."
  
  

Mistaken Identity

• Other types of adjustable wrenches that are incorrectly called monkey wrenches include the Stillson pipe wrench and the crescent wrench. The Stillson pipe wrench differs from the monkey wrench in having toothed horizontal jaws, with the lower jaw fixed while the upper jaw can be moved up or down with a knurled screw. The crescent wrench has smooth vertical jaws offset from the perpendicular of the handle by 15 degrees. The movable jaw can be moved sideways with a knurled screw.