A wheel and a caster are not the same thing, but often these words are used to refer to the same object. When a customer uses the words, "wheel" and "caster" interchangeably, it often creates confusion. Here is the difference: A wheel is a round object that rolls. A wheel rotates on an axle or shaft that passes through the center of the wheel. A wheel can be solid or spoked. Wheels made of just one material include solid all polyurethane wheels, steel wheels, V-groove wheels, hard rubber wheels, polyolefin wheels, phenolic wheels, nylon wheels and high temperature wheels. Wheels that are made essentially of just one material are almost always solid rather than spoked design.
Wheels that are made in a spooked design usually have a tire molded to another material. Most of the time tires are molded to a solid core which is the center or circular disk supporting the tire. Wheels with a solid core tend to be stronger than wheels that have spokes for a center.
The phrase "mold-on wheels" refers to wheels that have a tire molded onto another material that comprises the center of the wheel. Most of the time the center or core of a wheel is made out of one of the following materials: aluminum, iron, steel, nylon or polyolefin.
The tire that gets molded onto the center of a wheel is usually made from rubber or polyurethane. Rubber tires are made from many different compounds and in many durometers (hardness). The same is true of polyurethane tires. When selecting a wheel it is rare that any consideration is given to the proper tire compound or hardness for a specific application.
Most people choose a wheel on the basis of its rated capacity or its diameter. We have included on our web site a Section called "How to Select the Proper Caster", which describes most of the major factors one should consider before making a selection. When you do not select the proper wheel for your special application, it will not perform as efficiently as it would had you chosen the right wheel.
Unfortunately, most sales people who sell wheels know too little about them. Our staff is a valuable resource ready to assist you in the selection of the right wheel for your specific application. They have a vast amount of product knowledge and experience in wheel applications.
Now that we have explained what a "wheel" is, let us distinguish it from a "caster". All too often, customers call and say they want to buy "wheels" when in reality, they wish to purchase "casters". So, what is a "caster"?
To start with, one component of a caster is a wheel. Once a wheel is installed in a frame it becomes part of a caster. The frame is often called a caster bracket, rig or fork. All of these words are used to refer to the frame which houses or holds the wheel. The major components of a caster are the wheel and the frame in which it is held.
A caster frame can be either a swivel or a rigid frame. If the frame is a swivel type, then with a wheel installed, it is called a "swivel caster". A swivel caster is capable of rotating 360°. A chair caster or a caster on the bottom of a furniture mover's dolly, are examples of a swivel caster that most people are familiar with.
If the caster frame is rigid, then with a wheel installed, it is called a "rigid caster". A rigid caster is primarily utilized for straight line travel, meaning rolling forward or backward.