Sizing replacement casters and wheels

Author: Marvin Walker

When it comes time to pick out the right set of casters and wheels for your transport unit, knowing how to measure each is important. Many times you can get them together as a packaged deal, which can simplify life. One thing you have to make sure of with both is that they match the load weight of your transport unit. Then you need to know how to size them both to get the right fit.

What is the difference between a caster and a wheel?

A caster is the metal or plastic structure that holds the wheel in place on a transport unit. It consists of the axle, axle arm and mounting base. The brakes may also be incorporated in the caster as well. The wheel will only be the wheel with the inner rim insert to go over the axle. It generally will not have a brake system attached to it, and can be made of rubber or polyurethane.

How do you measure them for replacement?

Measuring a caster and measuring a wheel are two different things. You want the diameter for each, not the circumference. This will tell you the height of the wheel, but you also want the width. Then you have to measure the caster body. You will need to know the width of the axle, and the height from the center point of the axle to the caster body. This will insure that your wheel will be able to move freely when installed. If you are just replacing the caster, make sure you also measure the base (the attaching plate). It should not be able to be seen from the top of the transport unit when installed.

Should you replace the set all at once?

This is one of the most frequently asked questions about casters and wheels. The answer very much depends on the reason for you needing new wheels. If there is uneven wear, then you want to consider the cause of the wear. If you are noticing wear on all of them, then it is best to replace them at least in pairs. When you are doing this, replace the pairs across the width of the unit, not the length. In other words, replace both front casters, not all of one side. This will help retain control over the transport unit when it is in motion.

Consider the wear when ordering

There is one other thing you should be looking at when sizing your replacement casters and wheels. Like any other wheeled vehicles, the wear on the wheels is going to reveal if anything is going wrong with the transport unit, or if the loading habits are creating a problem. If you only need to replace one or two wheels off a 4-wheeled unit, it may be time to replace the trolley. If the trolley frame gets bent it can shift the load to one wheel, resulting in wear. Also, look to see if the loading habits are the cause. If you are loading a trolley past its weight range that can also result in uneven wear.

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