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Factors that determine how fast you can tow a polyurethane wheel

We get asked a lot about how fast can polyurethane wheels go? Since many factors are involved, I will lay out some of the more critical things determining how fast your polyurethane wheel can go.

The first item to address is the bearings. If you aren’t running precision sealed ball bearings or precision tapered roller bearings in your wheel, do not run the wheel faster than walking speeds and intermittent use. If you are running ball bearings or tapered bearings, refer to the L10 life ( L10 life is calculating, with 90% reliability, how many hours a bearing will last under a given load and speed) for the bearings you are using. Typically, caster applications won’t meet the bearing’s top speed.

After you have the correct bearings in the wheels, the next thing to do is look at the catalog rating of the wheel you want to use. Most caster catalogs will have a rating of “walking speeds,” which is 2-3 mph and intermittent use. This means not running the wheels for more than 45 minutes during an hour. Wheels designed for continuous use or for powered applications have a different speed rating – usually 5, 7, or 10 mph. If you want to run your wheel faster than the catalog rating, your next step is to contact the manufacturer.

Testing polyurethanes for higher loads and speeds

When you contact the manufacturer with your application specifics, they will plug those specifications into a model or compare them to physical testing to see whether the wheel can withstand higher loads or speeds than the catalog states. This testing is due to the nature of polyurethane. Polyurethanes are not perfectly elastic materials. When deformed, a urethane’s stored energy returns as the urethane returns to its regular shape. The remaining energy converts to heat due to the polymer chains sliding and rubbing against each other during deformation.

What does this all mean? A urethane tire generates heat if it is deformed more (when it’s carrying heavier loads) or if it is deformed more often (when it’s running at higher speeds).

Purple Polyurethane WheelsBecause not all urethanes are the same, each type of urethane will generate different amounts of heat. This is why you see some wheels that are good on pushcarts and some that can go up to 70 mph on roller coasters. Many high load/high speed or continuous-use applications utilize expensive urethanes. These urethanes generate less heat and last longer than a standard urethane wheel.

For applications at walking speeds or infrequent use, the catalog rating will suffice for your polyurethane wheels. If your application requires something more demanding, your safest route is to contact the manufacturer to discuss your application.

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