Often referred to as a Crescent Wrench, "one size fits all" pretty well describes this tool, the bottom jaw moves, by turning a knurl, to fit the nut. They are available in miniature sizes for key rings up to 24" long for heavy duty machinery. An 8 inch is a good size to have in your tool box. When using an adjustable wrench the movable jaw should always face the direction of rotation.

Allen Wrench

These are hexagon shaped wrenches bent a right angle that fit into allen head bolts or set screws, some sets now come with a ball on the long end that will allow the wrench to be used at an angle. Most pulleys have an allen set screw attaching them to the motor shaft.

Box End

The box on this wrench completely surrounds the nut, they usually have twelve points so the wrench can be reset after rotating only a partial turn. Each end is a different size so one wrench will fit two sizes of nuts.

Combination Wrench

This wrench has a box on one end and an open end on the other and has become the most popular type of wrench used by the home mechanic or handyman.

Open End

Each end of this wrench is open, the ends are angled to work in close quarters. Each end is a different size so one wrench fits two sizes of nuts.

Socket Wrench

Socket wrenches are usually purchased in sets that include various sized sockets, a rachet handle and extensions. Allen head and Phillips head sockets are also available.