How to Select a Castor?

The selection of a castor can have several deciding factors, when deciding the correct type of Castor to use for your application.

1.  Calculate the Maximum weight on each Castor.  Extra consideration should be taken for unequal loadings etc.
     It is always better to use a higher capacity castor than you actually require.

Each Castor has a maximum rated weight.  It is important to note that this "maximum" weight includes the weight of the equipment, the weight of any payload and importantly any dynamic forces such as shocks and bumps. (for example if the equipment is being transport on the back of a vehicle, or moving over uneven ground, this will induce considerable extra force in addition to the static weight of the equipment). - Customers are advised to considerably de-rate the castor maximum load for such scenarios.

Customer are advised to take into account that a castor may loose contact with the ground (due to uneven ground and the general environment. If a castor looses contact with the ground the static weight and dynamic forces will be distributed over the remaining castors (for example if you have 4 castors, consider the weight may be spread over only 3 castors.

2.  Remember: Larger Diameter wheels provide more manoeuvrability.

3.  Soft Wheels such as Black Rubber Castors, offer more resistance/grip, and are therefore better for hard surfaces (such as concrete floors & castors for warehouse equipment). They also offer some protection to the floors surface and are considered Low Noise. Black Rubber Castors are generally used for light & medium weight equipment, whereas Polyurethane castors, which are hard but flexible, can be used for lightweight to heavy duty equipment.  Hard Wheels such as our Nylon Castors & Black polypropylene Castors are suitable for both Hard surfaces & Soft Surfaces.  They offer low resistance/grip making them easy to move.  Black Plastic (Polypropylene) castors are low cost, where as Nylon castors are used where longevity of life is required.

Black Rubber Castors  -  Good Grip & Control, Good Floor Protection & Low Noise, Heavy Duty and ideal for hard surfaces and uneven floors
Polyurethane  Castors  -  Good Appearance, Good Grip & Control, Reasonable Floor Protection, Low Noise, & Long Life, ideal for hard surfaces
Polypropylene Castors -  Ease of movement, suitable for hard & soft surfaces (such as carpet), Low Cost.
Nylon Castors - Ease of movement, suitable for hard & soft surfaces (such as carpet), Heavy Duty & Long Life.

4.  Fixing Type
Plate Fixing - Most robust type & very popular fixing method.  Uses 4 screws/bolts per castor to fit to equipment.  The plate distributres the load, and reduces stress on castor. Plate Fixing type generally offers longer life.

Bolt Hole Fixing - Easy to install where existing bolt hole exists, however better for light loads

If possible, choose the Plate Fixing Castor for longer life

5.  Maneuverability - Fixed, Swivel or Swivel with Brake

This depends on your application, how often it is going to be moved, and where you will move it to.  The most common combination is 2x Swivel & 2 x Swivel with brake, with the braked version at the rear, and the non-braked castors at the front. This allows for 360 degrees of movement, and the brake can be put  on when not in use.

6. Number of Castors.   As a general rule castors should not be spaced out more than 1.5 meters apart, otherwise excessive stress may be put on the wheel hubs and swivel bearings during maneuver.   

In addition, if your equipment is taller/higher than its width and/or length, or running over uneven ground, this will put increased forces on the wheel hub and bearings. In this instance we would suggest a castor with a large diameter swivel bearing is used (such as the 100mm, 125mm and 150mm Black Rubber Castors, or the 80mm, 100mm and 125mm Nylon Castors - subject to suitable load capacity).  Contact us if you have such a application and we will be more than happy to advise.


7.  There are many other factors to consider such as contamination, shock loads, uneven load distribution, temperatures, non-marking materials etc.  The list can go on & on.  

The most important thing is to consider all forces, both static and dynamic, when selecting a Castor.  

If you have any doubt about which castor is suitable for your application, or if you have an application where the products on our website are not suitable, please contact our sales team for expert advice. 

All information on this website ( Bulldog Castors ) is given for guidance only. It is important that the customer is happy with the selection of castor for their own application & use.