A castor wheel is a wheeled fitting that attaches to the base of objects such as trolleys, carts, machinery, and furniture. This will allow them to be moved easily across floors. A castor assembly consists of a wheel, a mounting fork, and either a fixed or swivel top plate. Castors are rated by load capacity, wheel size, and material, which determines which application they are suited for.

Both spellings refer to the same product. “Castor” is the correct spelling in New Zealand, Australia, and other Commonwealth countries. “Caster” is the American English spelling. You will see both used in product catalogues and online – either is acceptable, but in New Zealand “castor” is the standard.

The lifespan of a castor wheel depends on the load it carries, the floor surface, the frequency of use, and the wheel material. In light to medium duty applications, good quality castors can last several years with minimal maintenance. In heavy industrial environments with constant use, castors may need to be inspected and replaced more regularly – particularly the wheel and swivel bearing. Polyurethane-treaded castors tend to last well on smooth floors, while cast iron wheels are more suited to rough or high-temperature environments where other materials would degrade. Regular inspection for flat spots, cracked wheels, seized bearings, and worn brakes will help maximise service life.

Most castors from Vartec Industrial use a swivel plate or fixed plate mounting, which bolts directly to the base of the equipment using four fixing holes. To install, position the castor plate over the pre-drilled holes on your equipment, insert the appropriate bolts, and tighten securely. Always ensure the mounting surface is flat and structurally sound. For heavy-duty applications, use grade 8 bolts and check that the bolt pattern matches the castor plate dimensions. If fitting castors to a new frame or trolley, the plate dimensions and bolt hole spacing are listed on each product page at vartecindustrial.co.nz.

You should replace a castor wheel when you notice any of the following: flat spots or chunks missing from the wheel tread, cracking or splitting of the wheel material, a seized or rough-running swivel bearing, excessive wobble or play in the wheel axle, or a brake that no longer holds securely. Worn castors increase the effort required to move loads and create a risk of equipment tipping or rolling unexpectedly. In industrial environments, it is good practice to inspect castors at regular intervals rather than waiting for visible failure.

To calculate the load capacity required, take the total weight of the equipment plus its maximum load, then divide by the number of castors being used. As a safety rule, always apply a safety factor of at least 1.3 to 1.5 to account for dynamic forces such as impacts, ramps, uneven floors, and momentum during movement. For example, if your trolley and its contents weigh 400 kg and you are using four castors, each castor should be rated for at least 130–150 kg (400 ÷ 4 × 1.3–1.5). It is always better to overspec your castors slightly than to run them at their maximum rated load continuously.