How to specify castors

It is important to specify the correct type and model of castor for a particular application, otherwise the performance may not be as required or the castor could fail prematurely. On the other hand, 'over-specifying' a castor can be unnecessarily costly. The following guidance should help to get the specification right.

1. Load capacity

As a general 'rule of thumb', the load capacity for the castor should be one third of the sum of the unit weight and the maximum load capacity. For example, on a trolley designed with four castors, take the total weight of the trolley, plus the maximum weight the trolley must carry, and divide by three to give the castor load capacity.

2. Swivel or fixed?

Swivel castors rotate to improve manoeuvrability and can be equipped with a brake to locks the wheel or wheel and swivel. Some ranges are also available with a directional lock. Fixed castors cannot be swivelled or have brakes.

3. Fittings

Castors are available with a wide variety of fittings. The choice of fitting is largely a question of the frame to which the castor must be fitted. Fitting types include: single bolt hole; top plate with multiple fixing holes; and expanding adapters for square or round tubes.

4. Wheels and tyres

In most cases, the larger the wheel, the higher its load capacity and the easier it is to move. Different wheel and tyre materials are available to suit various floor surfaces.

5. Bearings

There are four types of bearings to help reduce rolling resistance: plain bore with no bearings (for light loads moved over short distances); roller bearings (for easy movement of heavy loads); ball journals (for lower friction and a longer working life for heavy loads and constant movement); and tapered roller bearings (for the best performance and higher load capacities).

More information

To find out more about specifying castors, and to find contact details for experts with whom you can discuss particular applications, go to the Technical Support section of the Ross Handling website at www.rosshandling.co.uk/technical-support.asp.