What Are Coach Bolts Used For?

Bolts or screws are normally used to attach pieces of material together or to secure something onto a sturdy base. While it is not really that difficult to spot a bolt or screw in a toolbox, it can also vary in shape and size depending on the purpose it was designed for.

One particularly useful bolt is the coach bolt. Coach bolts are also called carriage bolts or round head square bolts and are known for their distinct appearance, as well as for the variety of their uses in the field of construction. Coach bolts are made even more distinct by the circular shape of their shank, which is immediately joined to the head of the bolt via a square piece of metal. The dome-shaped head of the coach bolt, on the other hand, is a shallow disk, which allows the bolt to easily slide into a round or square wooden hole if needed.

What makes coach bolts particularly useful is their inherent ability to “self-lock” (courtesy of the square piece of metal directly underneath the dome head) when installed with a single tool such as a wrench or a pair of pliers.

Because of their secure locking mechanism, coach bolts are usually used to attach heavy segments together and are a highly preferred alternative to relatively flimsy nails and screws. They were initially designed to join metal pieces and heavy timbers together; thus, one of the common uses for them is for hammering iron reinforcements onto heavy wooden beams (although they have also been used to attach pieces of different kinds of heavy timber together recently). The newer coach bolts also come with a heavily threaded shaft, making it easier for them to dig into the surface of bare timber wood.

Since attaching joints and segments together is a critical step in any construction project, be it big or small, it is possible to find many kinds of coach bolts that serve different functions. A small coach bolt is advisable for home repairs and for DIY construction projects while massive ones are generally reserved for structures that are just as enormous in scale (e.g., large buildings).

One distinct variation on the coach bolt is called the plough bolt. Plough bolts are flush-fitting bolts equipped with a countersunk bolt head. As their name suggests, plough bolts were originally designed for iron ploughs. The latter farm tools are comprised of a plough share, a shank, and a mould board for attaching the two together.

Since the plough share is the end of the farming tool exposed to the biggest amount of wear and tear, it tends to wear down more quickly than the other parts of the tool. Thus, the plough bolt’s function is to attach replacement plough shares onto the mould board so that it wouldn’t be necessary to replace the entire tool each time the plough share wears out.

While coach bolts and their variations are highly useful for any construction project, it would be best to select the right kind for each purpose.