Elevator Bolts

Elevator bolts may date back to the mid-1800s and were originally used to attach elevator buckets to a belt so grain could be lifted for storage in the vertical bins of a grain elevator. Today, these bolts enjoy wide usage in a variety of applications unrelated to conveyor systems: they secure flooring, are used as leveling legs, and you’ll find them on snowmobiles and skateboards and wherever head clearance is crucial. Elevator bolts have a “large circular head with a flat top surface and a shallow conical bearing surface, and an integrally formed square neck under the head.” Elevator bolts are also known as:

belt bolts, Norway bolts, No. 1 Norway elevator bolts, elevator screws, flat countersunk head elevator bolts.

Since the head is designed not to turn, they are usually tightened by torquing a nut. As a leveling leg, though, they can be used with an internally threaded (tapped) hole and tightened by turning the bolt’s square neck.

Threads are standard right-hand and Unified inch coarse series (UNC, Unified National Coarse). Short lengths are usually fully threaded.

Typical elevator bolt sizes are 1/4″, 5/16″ and 3/8″ in diameter and lengths span from about 3/4″ to 3″. Measure length from the top of the head to the threaded end of the bolt.

Average head diameter ranges from about 3.1 to 4 times the nominal bolt size making it the largest diameter flush head style and the largest in the round head bolt family, which significantly reduces the chance of pull-through. Table 1 summarizes head diameter and height, and square neck width and depth.

Grade 2, steel, zinc plated, is a common grade, material and finish.

When elevator bolts are installed flush in wood, the square neck relies on a snug fit to prevent bolt rotation as the nut is tightened. Consequently, consider drilling the hole the same size as—or a little larger than—the bolt’s shank to ensure a tight fit for the square neck.

When installing in wood, use a large diameter washer under the nut to distribute clamping force over a larger area and minimize compression of the wood.

Refer to American Society of Mechanical Engineers Standard ASME B18.5, Round Head Bolts, for specifications relating to elevator bolts.