Wheel bearings – Their purpose and why they wear out

What is the purpose of a wheel bearing?

The wheel bearing serves two very important purposes in your wheel. It minimizes the friction created from tire rotation and help support the trailer’s weight. The bearings must be in near perfect condition to be able to perform. The seals must also be leak free to keep the lubricant inside the bearings and contaminants out.

What causes a wheel bearing to wear out?

Your wheel bearings get relatively hot running up and down the roads. And while the metal in your wheel bearings is heat treated to withstand these high temperatures, sometimes when a bearing is cooling off the components can create a vacuum that draws in air, debris, and who knows what else. Hopefully, your seals are in good working condition to expand and contract to protect the integrity of your wheel bearing, but seals break down with age. (This is why our employees replace every seal that we touch with new).

The contaminants circulate through the grease and the components of the wheel bearing begin to show signs of wear. Once a bearing begins to show wear, the process to catastrophic failure is accelerated. The bearing begin to loose it’s resilience to heat and worn seals allow more and more contaminants.

How do I know if my trailer needs new wheel bearings?

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Wheel bearing beginning to show wear from a trailer we inspected last week at AC Farm Services.

It’s very difficult to detect a failing wheel bearing as it does not happen very often and when they do wear out, it can happen quite quickly. Common signs you may notice include abnormal tire wear, grinding or roaring noise from the tire area, or looseness in the wheel.

Uneven tire wear is commonly attributed to worn out wheel bearings. Wheel bearings rarely wear evenly and if one tire is showing more wear, the wheel bearing in that tire/wheel may not be functioning correctly.

If you hear a loud grinding sound coming from your tire area, you may be hearing the metal to metal sound of a catastrophic wheel bearing failure. This can also cause a vibration in the steering wheel. Maybe your seal failed and the lubricant leaked out, maybe contaminants caused a bearing to break, but this means your wheel is no longer able to safely carry weight.

If you have your trailer wheels off the ground, you can check for wheel “wobble” that indicates worn out wheel bearings. If you can rock your tire on the axle, your wheel bearing are unsafe to bear weight. This check does not catch wheel bearings that are beginning to wear.

That’s great, can you help me?

Yes, our Annual Safety inspection checks all weight bearing components, including checking the integrity and grease in your wheel bearing and replacing seals.

Call or email us to schedule your trailer safety inspection!

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