Many people may not know what a caster is, but when they see it, they may simply define it as a wheel.
But a caster is more than just a wheel!
In materials handling, as in many other fields, when it comes to looking for a certain product, you have to be very specific in naming what you want. And knowing the correct name of the product is key there. So let’s define exactly what the difference between a caster and a wheel is.
Wheels
We’re all familiar with the wheel. It’s a round object that will have a hole in the center to use as a shaft to make it work for whatever purpose you 
need, and that can be anything. One might also define it as a circular cylinder of greater or lesser width that spins around on an axle, much like the wheels on a car. The wheel is used for many mechanical purposes.
The invention of the wheel 5000 years ago has changed the way humans live, work and create. But it’s only been about 150 years since the even more versatile caster was first patented. If you’re inquiring about the difference between a wheel and a caster, chances are you’re more interested in the caster and what it can do for you.
Casters
A caster does indeed include a wheel. But, it is more than a wheel. It is an assembly that contains both a wheel and a bracket for it, sometimes called a “fork,” or “yoke” And this bracket that contains it is what separates it from the regular wheel. So when you’re looking to replace the “wheel” at the bottom of your chair or cart, you are actually looking to replace the caster assembly. So be sure to type in “caster” in your search engine, or if you’re going to a brick and mortar store, ask your sales associate for a caster, not a wheel. You’ll save yourself a lot of time.
Casters are mounted to an apparatus or piece of equipment to make that apparatus moveable. You’ll find that casters come in two different styles:
- The kind that features a flat bracket with mounting holes so that you can fasten another flat surface flush against it – Plate Mounted,
- Or the kind without the flat surface that can thread or otherwise lock into the attaching object via a threaded pintel or a spring retention clip – Stem Mounted.
Those are the styles. But casters can also be separated into two categories:
Swivel Casters
The swivel caster is designed so that the wheel in the caster can rotate 360 degrees while under load. As the center hub of the wheel revolves around the center of the swivel section it is said to “cast” in that small circle. Thus, caster! This essential swiveling feature of casters makes it so much easier to move heavy loads and turn tight corners in a warehouse. Swivel casters are available as locking casters, plate casters, stem casters, and kingpinless casters. A good example of a swivel caster is the General Duty Caster from Shepherd.
This caster has a zinc finish and is RoHS compliant. It also has a nickel-plated kingpin for a smoother swivel. This caster has been used for material-handling equipment, industrial equipment, and moving furniture. While the exterior of the caster is nickel-plated, you do have the option of choosing what kind to material you want on the actual wheel.
Here are your wheel options for the General Duty Swivel Model:
- Soft Rubber
- Polyolefin
- Hard Rubber
- Steel
All of the General Duty casters have a thread width of 13/16” and the swivel radius depends on the size of the caster. The swivel will increase according to the size of the wheel. Your wheel diameter can be 2”, 2 ½”, 3”, and 4”. The load that each caster can carry ranges from 80 – 120 lbs. and of course the larger the wheel, the more weight it can carry.
Other types of casters are the Ball Bearing and Kingpinless. You can look these up on the Douglas Equipment website.
Rigid Casters
Rigid Casters, which are actually a misnomer as they don’t really “cast” at all, are also less commonly but more accurately known as fixed casters. They are simply a wheel mounted in between the legs of a bracket which does not swivel. Because of this, rigid casters are well suited for an application where materials must be moved forward and backward in a straight line, but not one where they must be turned around a corner. Because they do not feature a swivel section subject to perpendicular and other tangent stress, rigid casters are stronger than swivel casters and can handle higher weight capacities. The Regent Rigid Top Plate Model is a good example of the rigid caster.
This top-selling rigid caster features a zinc finish. It has double ball bearing raceways with an octagon washer on a threaded stem. What makes this particular model so special is that it has heat-treated raceways for increased wear and resistance. It is also RoHS compliant. Because it doesn’t have as much maneuverability, this caster is ideal for medical equipment, carts, furniture, and institutional equipment.
Here are your caster wheel options for the Regent Rigid Top Plate Model: 
- Soft Rubber
- TPR
- Hard Rubber
- Polyurethane
- Polyolefin
- Montech
- Vipor
All of the Regent Rigid Top Plate Model caster wheels have a thread width of 13/16” or 15/16”. Your wheel diameter for the Regent can be 3”, 4”, and 5”. Here again, the swivel radius (as minimal as it is) depends on the caster options. Depending on the size of wheel you choose, the swivel can go from 2 ½”, 3 7/16”, and 4 1/8”. The load that each caster can carry ranges from 110 – 160 pounds.
Most rigid casters come with brake options. This model’s options include Friction brake or Tread Lock Brake. It really depends on the kind of brake you want and if it’s offered as a standard option. If it isn’t and you prefer to have a brake, we can arrange to have one made for you.
It’s Whatever You Need!
At Douglas Equipment, when it comes to helping you select the perfect caster, it’s whatever you want. We are in partnership with several caster manufacturers, including Colson Casters and Blickle Casters, that can provide you with the caster you need. Call our customer service department today to discuss your options, or browse our website to see what all we have to offer. Our consultants are more than happy to assist you. Call our toll free number at 1-800-451-0030 or contact us online.
