What Is the Difference Between Castor and Caster?

When it comes to picking the right wheels for your equipment or furniture, the words “caster” and “castor” can be confusing. They mean the same thing, but which one you use depends on where you are. In this guide, we’ll explain the difference between these words and what you need to know when you’re buying castors or casters.

The difference between “castor” and “caster” is primarily regional. “Castor” is the British English spelling, While “Caster” is used in American English. Both words describe the same type of wheel component that attaches to equipment or furniture, making it easier to move.

Now that we’ve cleared up the spelling difference, let’s dive into what castors and casters are, how they work, and why it’s important to know the difference when you’re buying.

Is Castor or Caster?

One of the first things to clear up when purchasing wheels for equipment is the spelling difference between caster and castor. This confusion mostly stems from regional differences. In American English, the term “caster” is used, while in British English, “castor” is the preferred spelling. Despite the difference in spelling, both terms refer to the same component: a wheel attached to the bottom of furniture or equipment, making it easier to move. So, whether you’re in the U.S. or the U.K., you’re still talking about the same functional part.

What Is a Caster and Castor?

Casters (or castors) are wheels designed to be attached to the bottom of equipment, furniture, carts, or machinery. The primary purpose of a caster is to make moving heavy or bulky items easier. Casters are usually composed of a wheel mounted inside a frame or housing, which allows it to rotate freely.

There are two main types of casters:

• Rigid Casters: These casters only allow movement in a straight line—forward and backward. They’re best used in situations where controlled, linear movement is required, such as in carts or trolleys used on assembly lines.
• Swivel Casters: These casters can rotate 360 degrees, providing greater maneuverability. They’re often used in applications where flexibility and turning ability are important, such as on office chairs or hospital beds.

Whether you’re outfitting a heavy piece of industrial equipment or choosing wheels for your office chair, understanding these components is crucial for smooth operation.

What Is the Difference Between European Castors and American Casters?

While casters and castors are functionally the same, there are key differences between European and American models, particularly in design, standards, and certifications:

• Design: American casters tend to be more robust, designed with heavier-duty applications in mind. The wheels are often thicker and can support larger loads. European castors, however, typically focus on precision engineering and smaller, more compact designs.
• Measurement: In the United States, caster sizes are usually given in inches, while in Europe, millimeters are more commonly used. This means that if you’re buying casters internationally, it’s essential to double-check measurements to ensure compatibility with your needs.
• Certifications and Standards:
  • U.S.: PAHs (Polycyclic Aromatic Hydrocarbons), ASTM (American Society for Testing and Materials)
  • Europe: PAHs (Polycyclic Aromatic Hydrocarbons), REACH (Registration, Evaluation, Authorisation, and Restriction of Chemicals), RoHS (Restriction of Hazardous Substances), ISO (International Organization for Standardization)

Understanding these differences is important, particularly if you’re sourcing casters for industrial or regulatory-compliant applications.

What Are the Two Main Types of Casters?

Casters come in two primary types: rigid (fixed) and swivel. Knowing the differences will help you choose the right type for your needs:

• Rigid Casters: As the name implies, rigid casters don’t swivel and can only move the equipment in a straight line. These are ideal for situations where linear movement is essential, such as in carts or trolleys used on assembly lines.
• Swivel Casters: These casters can rotate 360 degrees, offering more flexibility. They’re ideal for applications where the equipment needs to be maneuvered in tight spaces or around corners, such as office chairs, hospital beds, and shopping carts.

When choosing between the two, think about the movement you require for your equipment. If your needs include navigating tight spaces or rotating 360 degrees, swivel casters are the best choice. For straight-line movement and stability, go with rigid casters.

Units of Measurement: Inch vs. mm, kg vs. lbs

When you’re shopping for casters, you may encounter a mix of measurement units, depending on where the product is manufactured. Here’s a breakdown of what to expect:

• Inches vs. Millimeters: In the U.S., caster sizes are usually listed in inches, while in Europe, millimeters are the standard. Make sure to double-check the measurements when buying internationally to avoid confusion and ensure compatibility with your equipment.
• Kilograms vs. Pounds: Weight capacities for casters are typically listed in pounds in the U.S., while kilograms are more common in European specifications. Knowing the weight of the equipment you’ll be moving will help you choose the correct caster with an appropriate load capacity.

Certifications and Standards

Casters are subject to various certifications and standards to ensure safety, quality, and regulatory compliance. While both the U.S. and Europe have stringent requirements, there are some key differences in the certifications and standards they follow:

• U.S. Certifications and Standards:
  • PAHs (Polycyclic Aromatic Hydrocarbons): Testing to ensure no harmful chemicals are present.
  • ASTM (American Society for Testing and Materials): Standards for performance, load capacities, and durability of casters.
• European Certifications and Standards:
  • PAHs (Polycyclic Aromatic Hydrocarbons): Similar to the U.S., Europe also tests for harmful chemicals in caster materials.
  • REACH (Registration, Evaluation, Authorisation, and Restriction of Chemicals): A comprehensive regulation ensuring the safety of chemicals used in manufacturing.
  • RoHS (Restriction of Hazardous Substances): Focuses on limiting hazardous materials like lead, mercury, and cadmium in caster production.
  • ISO (International Organization for Standardization): Standards to ensure consistent quality control and manufacturing processes.

These certifications help buyers choose casters that meet safety, environmental, and performance standards based on the region they are sourcing from.

Summary

In conclusion, knowing the difference between casters and castors—and understanding the regional standards, types, and certifications—will help you make the best choice for your needs. Whether you’re putting wheels on furniture, industrial equipment, or office chairs, paying attention to these details will help you get the best performance and longest life.