Your Quick guide to Selecting Castors and Wheels
Use this guide to help identify the correct castors or wheels for your need.
To make sure that you are selecting the correct Castors, the total load of the unit you want to maneuver must be considered. Applying the following equation can be used to calculate the maximum load capacity of each castor.
As an example, a trolley requiring 4 Castors, you take the total weight of the trolley, and add the maximum weight the trolley will be carrying. And divide by 3. This will determine the load capacity required by each castor, allowing for a margin of safety. The margin of safety (4th castor) will allow for different working conditions and uneven floor surfaces.
The next step is to choose a castor fitting (fixing top plate)
Castor Fittings – Bolt Hole Fitting
The housing (metal bracket that the wheel is mounted into) has a single central bolt hole fixing. The fixing bolt diameter of either M8 (8 mm), or M10 (10 mm) or M12 (12 mm).
Castor Fittings – Top Plate Fitting
A rectangular or square plate with 4 fixing bolts.
The 4 bolts allow for a strong fixing and distribute the weight evenly. Both the Top Plate Fixing as well as the Bolt Hole fixing are available in swivel, and swivel with a brake. The Top Plate Fitting is also available in fixed (Rigid) housing.
As a rule of thumb, the larger the wheel diameter, the more weight it can carry, and the easier it is to move. Bearings are used in the hub of the wheel to reduce friction and allow for ease of movement. Wheels are generally divided into main categories.
Hard Tread Wheels
These wheels are easier to push because of less resistance, but they have the tendency of being noising and the potential of damaging floors. Hard Tread wheels are manufactured in Cast Iron, steel, Nylon, Polypropylene, Aluminum and Phenolic.
Soft Tread Wheels
Using soft tread wheels, you may experience for resistance when pushing a trolley, however these wheels allow for quieter movement, and are ideal for floor surfaces that are prone to damage. Thermo Plastic Rubber (non-marking), Super Elastic Rubber, High Temperature Rubber and Pneumatic Nylon Rubber are some of the materials used in the manufacturing process
Wheels that are fitted to a housing to create a Castor Wheel have 4 types of bearings to help reduce rolling resistance. The application will determine the which bearing is used, as well as the working environment, load capacities and the amount of movement.
Plain Bearings – For lighter loads and moving short distances.
Roller Bearings – For heavier loads and moving short distances.
Ball -precision Bearings – For heavy loads and constant movement.
Tapered Roller Bearings – For extra heavy Loads.