You can’t choose the perfect set of casters without considering their load capacity. Casters, of course, are wheels with a mountable frame. They are commonly installed on the bottom of chairs, carts, toolboxes, tables, medical equipment and other objects to improve mobility.
Different types of casters, however, have different load capacities. Light-duty casters often have a load capacity of just 100 to 125 pounds, whereas medium- and heavy-duty casters can handle over 200 pounds. Below are several factors that affect the load capacity of casters.
Solid vs Pneumatic
Solid casters typically have a higher load capacity than pneumatic casters. Casters can be classified as solid or pneumatic depending on how their tires are constructed. Solid casters feature solid tires, whereas pneumatic casters feature hollow tires filled with air or inert gas. While pneumatic casters offer superior shock absorption — a useful characteristic for bumpy or uneven terrain — they can’t handle as much weight as solid casters.
Wheel Size
Wheel size affects the load capacity of casters. Casters with large wheels can handle heavier loads than those with small wheels. You can refer to the wheel diameter to determine the size of a caster’s wheel. It represents the size from the outer edge of the caster’s wheel to the opposite edge of the wheel. Some casters have a wheel diameter of just 3 inches, whereas others have a wheel diameter of 4 or 5 inches.
Material
The material from which a caster is made will affect its load capacity. Polyurethane and rubber offer an excellent balance of shock absorption and strength. They compress under heavy loads, which helps to absorb shock. Steel and cast iron, on the other hand, offer a higher load capacity at the cost of shock absorption.
Frame
Another factor that affects the load capacity of casters is the frame. All casters have a frame; that’s essentially what distinguishes them from plain tires. The shape, size and style of the frame, though, may vary. Casters with thick, heavy-duty frames can handle heavier loads than those with thinner, light-duty frames.
Number of Casters
How many casters do you plan on using? Each caster has its own load capacity, which is multiplied by the total number of casters to calculate the overall weight limit. If you install four casters with a 200-pound load capacity on an object, for instance, the overall weight limit will be 1,000 pounds.