We're talking about caster wheel size this time. I’m sure you can remember a time when this happened to you:
You’re at the grocery store getting soda for the big family picnic. You’ve got 8 cases in the cart and you are ready to head to the checkout line. Hands on the handle bar, feet firmly against the ground, you push... and nothing. The cart doesn’t budge. You pull back, it starts to roll, finally, and you are on your way.
This story is repeated day in and day out all over the place. Not just in grocery stores, but in factories, warehouses, and offices. The reason for it is simple, the wheels just aren’t big enough for the load. This month’s tip focuses on wheel size selection in respect to the application.
Think Bigger
Wheel size selection is critical when specifying a caster. A wheel has many dimensions by which we measure it, but for today’s discussion, we’ll focus on one: diameter. We could keep this short and sweet by saying, “A big wheel is easier to push than a small wheel.” But that isn’t the entire story. It’s true, but it’s not the right answer.
It is true that a bigger wheel size is easier to roll than a small wheel. But, if that were the only consideration, you wouldn’t be seated on a chair with 2” or 3” diameter wheels; you’d be sitting on 12” diameter wheels. Imagine getting in and out of your chair! It would most likely end up on the other side of your office. Beyond that, it would weigh getting on a couple hundred pounds! What this tells us is that application matters just as much as our rule of thumb. A small office cart does not need 8” x 2” medium duty industrial casters with polyurethane on iron wheels. It most likely needs a 3” or 4” diameter wheel in an institutional rig.
But Not Too Big
The size of the cart matters as well. A small cart needs small wheels, a big cart needs big wheels. That’s a rule of thumb we can go with. It’s pretty true and correct most of the time. An office mail cart, as stated before, needs 3” or 4” wheels. An 8’ long cart for moving aluminum automotive wheels will probably need 8” or bigger wheels. There is another size that matters too, height. If you have a high cart that is on a narrow or short base, consider smaller wheels. A larger wheel will raise the center of gravity up from the ground. A higher center of gravity increases the likelihood of the cart tipping over.
So when selecting your wheel for an application, consider that wheel size should be in proportion to load and cart dimensions. There rarely is one right answer for a caster application, but some answers are more right than others, just think of the 12” diameter wheels you are not sitting on right now. When you’re faced with selecting casters for a cart, give us a call at 844-863-4542, we’re here to help make this simple and easy. Our trained sales staff has experience with nearly every kind of caster and cart.
