A monkey wrench is a widely used tool that can be used to hold any number of materials in place. Invented in the 19th century, the first monkey wrenches were made from flat pieces of iron and measured 24 inches (61 centimeters) long. A monkey wrench has been described as having both an L- and F-shaped appearance. Basically, the monkey wrench has a fixed upper jaw with a lower jaw that can move up and down the wrench through a screw mechanism. It got the name "monkey wrench" because the movement of the lower jaw up and down the wrench seemed to look like a monkey climbing up and down a branch.
Once the monkey wrench was invented, a variety of modified wrenches and tools based on its basic design were also developed. Specialized wrenches, such as pipe wrenches, adjustable clamps and vice grips are all based on the standard monkey wrench, but they are designed to use in specific circumstances that can't be handled by a monkey wrench.
The monkey wrench can be used to clamp onto pipes and various fasteners such as lug nuts, bolts and screws. The jaws of the monkey wrench are attached to the fastener head: This is where you want to slide the lower jaw to fit the specific fastener with a strong grip. Once both jaws of the monkey wrench firmly grip the flat sides of the fastener, you can begin to apply pressure to either tighten or loosen the fastener. If you want to tighten the fastener, turn the monkey wrench clockwise. Conversely, if you want to loosen a fastener, turn the monkey wrench counterclockwise.
An Allen wrench is one of the simplest wrenches to use. The Allen wrench itself is a small L-shaped wrench with six sides. If you look at a cross-section of the Allen wrench, it looks like a hexagon. Since the Allen wrench has such a specific shape, it can only be used with items especially designed for it. If you've ever bought furniture you've had to put together yourself, the manufacturer likely included an Allen wrench for you to use when you have to assemble it.
In addition to assembling furniture, the Allen wrench is also commonly used for bike repairs. The unusual shape, plus the fact that the Allen wrench is small and light and capable of getting into hard-to-reach places on a bike, makes it particularly useful for cyclists to carry with them as they ride.
When you need to use the Allen wrench, stick the short end of the L shape into the bolt head and press down on the longer side of the L to turn the bolt. Of course, the Allen wrench will only fit in a hex bolt (a bolt with six sides), so don't try using the Allen wrench to screw in any other type of fastener.
The other most common way an Allen wrench is used is to pick a lock. Allen wrenches come in a range of sizes, so as long as you have one small enough to fit into a lock for which you've lost the key, you can use it to try to open the lock. Simply stick the end of the Allen wrench into the key tunnel and…sorry, we're not going to teach you how to pick a lock!