Carriage Bolt

Carriage Bolt has a round domed head and a square neck that grips the wood so the nut can be tightened from one side without holding the head. On poles it fixes crossarm braces and fittings. Specify diameter, length and the quantity you need.

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At a glance

Carriage Bolt at a glance.

Function

Fixes braces and fittings to wood

Carriage bolts fix crossarm braces, pole steps and light fittings where a smooth head sits on the outer face.

Square neck

The neck stops the bolt turning

The square neck is pulled into the bored hole as the nut is tightened, so the bolt cannot spin in the wood.

Product form

3/8 to 5/8 in, 1 to 7 in long

3/8–5/8 in (M10–M16) diameters, 1–7 in (25–180 mm) long with up to 1 1/4 in (32 mm) of thread, domed head and square neck to ASME B18.5, galvanized to ASTM A153, supplied with a square nut.

Also known as

Spanish-speaking crews call it perno carruaje.

US English: coach bolt
Español (US): perno carruaje

Trade names for the whole range ↗

How it works

Tap in, then tighten from the back

The bolt is tapped into a bored hole until the square neck seats in the wood. The square nut goes on the far side and is tightened with one wrench, because the neck holds the bolt still. The domed head is left with no edges to catch on climbing gear or conductors.

Common applications

Where it is used.

Application

Crossarm braces

Flat and V braces are fixed to the crossarm with carriage bolts. The domed head stays clear of insulators and conductors.

Application

Steps and small fittings

Pole steps, guards and small brackets use carriage bolts where the head faces workers. Nothing projects to snag a harness or glove.

Application

Timber fixings on site

Line crews also use carriage bolts in timber platforms and framing around substations. The same galvanized bolt serves each job.

What else is a carriage bolt called?

In Spanish it is a perno carruaje.

Why use a carriage bolt on a pole instead of a machine bolt?

The square neck under the domed head grips the wood, so the nut can be tightened from one side without holding the head and the smooth head leaves nothing to catch on climbing gear. That suits crossarm braces, steps and small fittings, where GV supplies 3/8 to 5/8 in (M10 to M16) sizes with a square nut.

Pole-Line Assemblies