What is a wrench used for?

Definition Wrenches are hand tools for tightening and loosening screws and nuts with angular head shapes.

Screw heads have different shapes that make it possible to turn the screw with the right tool. Either the screw head is angularly shaped or it has a recess at the top. A wrench is a tool with a recess that fits exactly around a square screw head. When the wrench is placed around the screw, the wrench encloses the screw head in such a way that both parts can only be turned together. The wrench is easy to hold and, as a lever, increases the force exerted when turning.

The recess on a wrench can be open to one side like a U. This shape is called an open-ended spanner. With a ring spanner, the recess is ring-shaped. Combination wrenches are also often used. They have a mouth on one side and an annular recess of the same size on the other.

Another type of wrench is the socket wrench. Socket wrenches consist of a drive part such as a handle, a crank or a ratchet and a set of several socket wrench inserts of various sizes and shapes. The socket wrench inserts are inserted over the screw head from above. Depending on the width and shape required, they can be exchanged on the drive part.

Screws and wrenches come in different sizes and widths. They are standardized, so it is easy to choose the right wrench. The wrench sizes are given in millimeters. As a rule, screws and wrenches with widths between 6mm and 32mm are used. Wrenches are usually made from chrome vanadium steel.

Not all screw shapes can be turned with a wrench. For screws with recesses in the round screw head, a screwdriver or an Allen key must be used, depending on the shape of the recess.