A ratchet wrench, also known as simply a "ratchet" or a "socket wrench," utilizes an internal ratcheting mechanism that allows the wrench to be spun freely in the direction opposite of intended force. This allows the user to "reset" the position of the ratchet wrench without having to remove it from the head of the bolt being tightened or loosened.

History

The ratchet wrench was invented by J.J. Richardson. It was patented on June 18, 1863. The first official illustration of the tool appeared in Scientific American magazine in 1864.

Design

The ratchet wrench contains an internal ratcheting mechanism that allows the user to tighten or loosen a bolt in a reciprocating motion---that is, without needing to remove the wrench from the bolt. The wrench connects to a bolt using "sockets" that attach to the driving head of the wrench.

Socket Points

Sockets come in many different different styles and sizes. Whether shallow sockets, which set the wrench close to small bolts, or deep sockets, which are longer for hard-to-reach applications, sockets have either six or 12 points. Six-point sockets fit to a bolt head in only one way and make contact with the entire surface of the bolt head. Twelve-point sockets provide an easier fit for bolt heads but make contact only with the edges of the bolt, making it easier to strip a bolt.

Extensions

Many accessories make sockets easier to use in certain situations. One is the extension, which extends the driver head for difficult-to-reach bolts. Along the same lines, swivel-head sockets allow the user to turn the wrench at an angle that is not perpendicular to the bolt. Breaker bars make the handle of the ratchet wrench longer to provide more leverage for stuck and hard-to-turn bolts.

Function

Most notably, ratchet wrenches are used in the field of automotive engineering and mechanics. Because of the way cars are set up, the ratchet wrench's expandability and ability to get to hard-to-reach places make it a popular choice for many mechanics.

Source:

Scientific American