Castors are used in all sorts of applications these days. Anything from household furniture to industrial component trolleys can be fitted with them in order to make the more mobile and easier to shift around by hand. However, not all castors are alike and specialised castors are needed in certain situations. If you need help selecting the right type for a particular application, then read on.
The first thing to say about castors is that they are not just a set of wheels. Castor wheels are a component of castors, but they need to be housed in some sort of frame for them to be considered castors. Most wheels are attached to a centrally rotating axle. In the case of castors, the axle does not connect to another wheel fixing elsewhere, like the rear set of wheels on a car. Instead, the castor wheel's axle is connected to a mounting frame. This frame can then be attached to the object that the castor is being used with, usually being screwed into place. Wheels for castors are made from a wide range of materials including polyurethane, which is hard wearing and good over concrete floors, steel, often used by furniture manufacturers in their products, and nylon, which is a multi-purpose material.
Fixed and Swivel Castors
Some castors are housed in a fixed or rigid frame which does not allow the wheel's orientation to alter. Although it can roll back and forth freely, this sort of castor is used where straight line travel is desirable. On the other hand, swivelling frames allow the castor to turn as the object it is attached to is pushed. A typical example of this would be a shopping trolley. Therefore, swivel castors tend to be used in places where tight manoeuvring might be required. Most swivel castors allow for a full 360-degree turn, but some restrict the amount of rotational movement that can be made. This creates a turning circle - much like you experience when steering a car.
Dual Wheel Castors
These castors are commonplace in applications where larger than usual weights are to be conveyed. Dual wheel castors tend to be found on things like postal trolleys and goods-in carts. The addition of a wheel on either side of the housing frame makes for a much stronger castor configuration. It can be particularly useful when you need to move a trolley over rough ground, such as gravelled pathways, and where larger wheels are therefore preferable.