Axles & Nuts

June 13, 2022

A caster is composed of 4 major components: the wheel, rig, axle, and nut.  To learn more about the wheel and rig, see our previous articles:

Wheels & Bearings Caster Rigs

The axle and nut hold the wheel and rig together, making the caster a caster. This article aims to help you pick out the right axle and nut for your applications.

Axle vs Bolt

Some customers may be tempted to use bolts that they already have as axles for their casters, but there is no substitute for a real axle. 

Both a bolt an an axle are designed to fasten an item, but the difference comes in the length of the treaded section. When the threaded section of a bolt comes in contact with a caster wheel, it wears only that one side of the wheel prematurely. This causes the wheel to lean in at an angle and makes the caster move more difficultly.

The threaded section on an axle is smaller in length and provides an ample smooth surface for the wheel to roll on. 

Composition

Our axles and nuts come in two different materials: steel and stainless steel.

Steel

Steel is the most common material used for axles and nuts, found on pretty much every caster. Steel hardware works perfectly well in most applications except for wet environments, which are harsh on the metal and cause it to prematurely rust.

Stainless Steel

If your casters are going to be in a wet environment, we recommend stainless steel axles and nuts. Stainless steel is more resistant to rust, thanks to its high concentration of nickel. Stainless steel will still eventually rust, but it will take a longer time.

High temperatures

Both steel and stainless steel do well against high temperatures. High temperature environments mainly determine your nut choice: a nylon lock nut, one of our most popular, will melt in higher heat.

Our go-to combination for high temperature casters is a plain nut with a split washer. The split washer keeps the nut from turning but allows it to be easily removed when it comes time to change out caster wheels.

Grease Fittings

Another consideration for your axle is whether you want a grease zerk. Axles with a grease fitting allow you to grease the wheel through the hollow center of the axle. In some cases, the wheel itself has a grease zerk which allows another way to grease your caster.

If neither axle nor wheel have a zerk, the wheel may need to be removed completely to grease it.

Installation

For the most part, putting a caster together is as simple as aligning the wheel with the rig, sliding the axle through, and tightening the nut. This is true for most casters, but there are a few things you must be mindful of while putting a stainless steel caster together.

When assembling a caster and tightening a nut, you may encounter a great amount of heat, especially with stainless steel lock nuts. In some cases, a stainless steel nut can literally weld itself to the axle. This means that a grinder or saw would be needed to remove the nut!

We recommend wrapping Teflon tape around the the axle's threads to prevent this. Teflon tape is rated for temperatures up to 500° F, so this still works for most high temperature applications.

Final Thoughts

The axle and nut are small in size but play a large "roll" for your caster. Which choices you make may be the difference in whether the caster will be able to be disassembled later for repairs or replacements.

 If you have any questions about caster axles and nuts, feel free to contact us or give us a call at 800-345-0425 (Mon-Fri 7AM - 4:30PM CST)!

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