About Furniture Castors & Other Castors
Shortcut Links1 Load Capacity 2 Wheel Diameter 3 Wheel Type and Tread 4 Fitting Type 5 Castor Body Style Terminology
Castors are pivoting wheels that attach to the bottom of furniture, trucks, trailers, and any other equipment in order to make them easy to move. Available in a wide variety of sizes, the castor you need will depend entirely upon your application.
To make sure that you select the right castors for your particular materials handling need it is worth taking a little time to look at the FIVE key features below. We hope that doing this will make selecting the right castor easier.
If you have particular concerns or are not fully confident of your choice please contact us on the number shown above or send in an enquiry, we will be happy to talk you through the details of your specific requirement and advise on the right product.
Selection Criteria for Choosing Castors
1 Load Capacity
What is the total weight (load) that the castors are required to carry? If castors are to be fitted to any form of trolley or frame, the weight of this should also be included in the overall figure.
2 Wheel Diameter
The larger a wheels diameter is, the easier it will roll and handle bumps. If you are fitting your castor to equipment that needs moving regularly it is advisable to use wheels of 150 mm diameter or larger. When fitting castors to equipment for only occasional movement, it is possible to use quite small diameter castors provided they have a sufficient load rating.
3 Wheel Type and Tread / Tyre Material
Hard Tread vs Resilient Tread
Hard tread wheels are the easiest to push and offer the easiest movement and mobility. Cast iron wheels are a standard as they are the strongest and most long-lasting. On the downside they corrode in damp environments, are noisy and cause damage and wear to all but the most robust flooring. A floor-friendly alternative is Solid Nylon which is unaffected by water and has a load capacity approaching that of cast iron. Nylon wheels are, light in weight and very hard-wearing.
Resilient tread wheels are kinder to floors and quieter in use but are not quite so easy to move from a standing start. For light, medium and heavy duty loads, resilient tread wheels offer many benefits. Softer tread tyres are also particularly suitable for power towing applications. For very high load manual handling applications, soft tread wheels should be ruled out as, although they may be capable of carrying a very high load, the force required to move equipment from a standstill would require the efforts of several men.
Tread / Tyre Materials
Cast Iron wheels combine strength and shock resistance with long life and economy. Cast Iron wheels will withstand extremes of temperature but may cause floor wear and can be noisy.
Solid Nylon wheels are the most popular choice as they will not damage solid compacted floors such as cement or tile etc and have good load carrying capacity. Nylon wheels are used widely in food processing areas.
Rubber tyred wheels are available in a wide range of sizes, load capacities and colours with a choice of nylon, plastic, cast iron and pressed metal centres. Rubber tyred wheels are suitable for use on most floors.
Polyurethane tyred wheels have high tear strength and abrasion resistance which gives them a life of up to 10 times that of rubber under similar operating conditions. Polyurethane is able to carry loads approaching that of cast iron. Polyurethane has a lower tractive resistance than rubber for the same load so is better for manual handling of very heavy loads. Polyurethane is not affected by greases and mineral oils.
Plain bore wheels are suitable for light to medium loads and where intermittent movement is required.
Roller bearings reduce the effort needed to move medium to quite heavy loads
Ball Journal bearings offer the best in low friction and therefore are very long lasting. Ball journal bearings are an essential choice for constant moving applications in all but the heaviest power towing situations.
4 Fitting Type
There are a good variety of fitting options available and the most suitable will depend upon the equipment you wish to fit the castors to, some of the most popular include:
5 Castor Body Style
There are three broad types of castor bracket available. Also frequently known as bodies or frames, they include:
Swivel brackets contain wheels which are free to swivel a full 360 degrees without restriction. The frame swivels about the vertical axis of the bearing which connects the lower part of the bracket to the fitting plate. The Castor wheel axle is usually offset.
Braked swivel brackets
Braked swivel brackets are the same as standard swivel brackets with the addition of a braking mechanism. Some braking mechanisms will brake the wheel only, to stop movement, while others termed ‘Total lock brakes’ will brake both the wheel and the swivel head to give a more rigid lock. Both style of braked castor is available from Mendip.
Fixed brackets do not swivel and so contain wheels which are only able to travel in one direction. When fitted to equipment care should be taken to ensure the axles are in alignment.
Light duty wheels and castors.
These wheels and castors are light and mainly used with appliances and equipment for internal applications. The load capacities go up to 100kg per castor. This type of wheel or castor is designed for travelling at low rolling speeds and manual handling only. They offer full manoeuvrability for lighter equipment and brake facilities. Frequently you will see this type of product on medical equipment, display bases, equipment for catering establishments etc.
Medium duty wheels and castors
These cover the widest area of application and are used widely in the industrial sector, both inside and outdoors. They are designed for manual handling at walking speed; the maximum load capacities go up to 400kg per castor. Largely maintenance-free, these castors are robust and will last a long period of time. Castors of this type can be equipped with wheel or swivel brakes and directional locks. Equipment of all kinds, including trolleys, pallets, working platforms, waste containers, owe their mobility to this type of castor or wheel.
Heavy Duty and Extra Heavy duty wheels and castors
Used to move heavy and extremely heavy loads. This type of castor has a much stronger design and in some cases will be suitable for higher travelling speeds. Load capacities for Heavy duty castors go up to 1000kg per castor, and Extra heavy duty castors will handle weights far in excess of that figure. For moving extremely heavy loads, twin wheeled castors are used. For applications with very heavy loads the castor frames are usually made from thick fabricated steel plate construction. The wheels and swivel heads are fitted with particularly robust bearings. Usually available with wheel or swivel brakes and directional locks. Other variations are available for more specialist applications. This type of castor ensures safe and permanent mobility for a wide range of heavy industrial applications.
An assembly in which a housing containing a wheel is free to swivel without restriction about the vertical axis of the swivel bearing with the castor wheel axle offset.
A swivel castor assembly which has the addition of a braking mechanism. Brakes will vary in type but are often a foot operated pedal style. Types of brake include wheel brake or total lock brake which will brake the swivel head as well as the wheel.
An assembly housing a wheel which cannot swivel about its vertical axis.
A revolving centre rotating freely on an axle of which the external part in contact with the ground can be the material of the wheel itself or tyre or tread of various other materials.
The horizontal distance between the centre of the wheel axle and the vertical axis of the swivel bearing: this may sometimes be known as trail (see Fig. 1).
The effort required to move a piece of equipment fitted with castors: this is usually expressed as a percentage of the total load carried.
The measurement from surface of flooring to top of bracket, also referred to as ride-height.
The width of the centre boss of a wheel. When wheels are being purchased to fit into existing brackets this measurement is vital.
The radius of the whole castor swivelling – usually larger in braked castors when a foot operated brake is present. Calculated approximately by adding offset dimension to half the wheel diameter.
Width of the tread of a wheel at point where it meets the floor surface.
The size of the hole through the centre of a wheel.
A component used to reduce friction between wheels and axle bolts. Plain bearings are fine for lighter duty applications. Roller bearings commonly used in castors do not increase load capacity but will make handling easier and prolong working life. Ball Journal bearings and Taper roller bearings are used on heavier applications and will absorb axial loads. These are essential for power towing applications.
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