For some reason, wrenches have a bad rap. If you are old enough, you might be familiar with a phrase that goes something like "Well, that's thrown a spanner in the works." Often the U.S. term of "monkey wrench" is substituted for the British "spanner," but in either case, it means that one's carefully laid plans have gone terribly wrong, calling forth the image of a heavy, cast-iron wrench being tossed into the gears or moving parts of an engine and thus rendering subsequent movement impossible, or at least calamitously noisy.
This is odd, considering that wrenches as tools are designed to do precisely the opposite. Pipe wrenches staunch water leaks, while socket wrenches, crescent wrenches, open-end wrenches, and their box- or ring-end counterparts keep machined parts in place so their moving components will run smoothly. Some wrenches may be less precise than others—an alligator wrench works by the brute force of the friction between its teeth and whatever is being turned, while the jaws of an adjustable wrench will only clamp as tightly around a nut or bolt as the strength of the tool's worm-screw will allow—but as a family, wrenches are designed to keep things together rather than being the cause of them coming apart.
Wrenches have been doing this sort of thing ever since the earliest days of the Industrial Revolution, when the machines that would help the world produce more goods at lower costs were built and maintained with, among other tools, wrenches. Special wrenches were designed to adjust and tighten fittings on everything from carriages to tractors to locomotives. Some wrenches were highly specialized (the pointed end of a spud wrench allowed an ironworker to line up holes drilled in two pieces of steel to make it easier to get a bolt through the holes before tightening the bolt with the wrench end), but more often wrenches were adjustable so a single tool could loosen or tighten a range fastening heads.
Farm wrenches were routinely designed for particular brands of equipment, with the brand's name either raised in relief letters on the wrench's handle or cut into it, so that one would actually grip words like Deere, Planet Jr., John Bull, or Litchfield when using the wrench. These tools often had open ends—in many cases, one end of the wrench might have two or three open ends, corresponding to the sizes of nuts and bolts most commonly used in adjustments or repairs.
Patented wrench designs boasting exclusive features came into vogue in the early 19th century. Solyman Merrick is often cited as one of the wrench's inventors, but his first patent, 8,153X, granted on April 18, 1834, was actually just an improvement to wrench patent 7,254X by Henry King, granted on October 25, 1832. Merrick did, however, patent the first screw-adjust wrench, patent 9,030X granted on August 17, 1835.
Other formidable figures in wrench history include Charles Stillson, who was granted a number of wrench patents between 1865 and 1876, and the brothers Loring and Aury Gates Coes, whose screw wrenches were commonly called monkey wrenches (the oft-told story that Charles Moncky invented the monkey wrench in 1858 is false). Famous wrench brands include Millers Falls, Elgin, Bemis and Call, Liberty, Giles, Trimo, Westcott, and Acme, which was just one of many companies that made steel wrenches with handsomely twisted handles.