The way castor wheels work is straightforward enough. In most cases, they are attached to the underside of the vehicle via a fixed top plate, from which the wheel assembly hangs.
A typical method of attachment is to use 3-4 screws or bolts, inserted through the pre-drilled holes in the top plate. Other popular methods of attachment include bolt hole and threaded stem castors. These are often preferred for either practical or aesthetic reasons.
- Bolt hole castors will normally be affixed in one of two ways, either via a threaded bolt or an additional tubular adaptor piece (the latter is especially common for basic, low-cost office furniture)
- Threaded stem castors generally come with the stem part included in the package; this is what you will use to screw directly into the vehicle you are mounting wheels to
The ideal choice of mounting method will again come down to how much weight each castor is expected to carry. Other factors that may influence your choice of mounting system could include the availability of practical mount locations, wheel size, turn/swivel radius of the castors, or how often you are likely to want to move the item around.
For a majority of large and bulky items of furniture or equipment, a common standard is to use at least four castors, one at each corner of the item’s underside. Exceptionally wide, long or heavy items may need more than this. Smaller products designed to be moved in specific ways - certain trolley types, for example - may require fewer.
In terms of the actual wheels themselves, we have already covered the basic single, double and compound castor configurations. However, there are several other important categories, types and features of castor wheels, such as:
- Swivel or fixed castors
- Heavy-duty or extra heavy-duty castor wheels
- Castors with brakes
- Small or hidden castor wheels
- Castors with tyres or other protective characteristics or safety features
Many of the above are designed for improved performance in specific applications, workplaces or environments.
It should also be noted that various hub types are available. For instance, the wheel hub can come with roller bearings, ball bearings, friction bearings, or plain smooth bore. The latter type features no bearings and is suitable for lighter loads.