Guide to Casters
Casters and wheels attached to heavy equipment can take the strain out of moving these items around. By choosing the correct caster you can make sure the equipment you are moving gets from A to B safely and that you haven't damaged the local environment in the process.
The wheels or casters you have chosen need to withstand the pressure put on them, so selecting the correct item from the start is important.
There are many types of caster and wheel to choose from, so decide on the type you want. This could be a swivel, fixed or one including a break. It is often sensible to use a combination, maybe using two breaking and two without, this can save money, since breaking every wheel is often not necessary.
Choose the way it needs to be fitted. This could be via a top plate, bolt hole, stem, expander or plugin pin. In our industry where the casters are often attached to flight cases, a top plate with four holes is the usual method. This is a particularly strong arrangement and suitable for the rigors of “on the road” use that these items of often subjected to.
The load is a key factor in making sure the wheel lasts and the whole assembly is safe. First work out the maximum load the wheels would be carrying and then decide on the fitting pattern.
As an example, and considering four wheels on a standard case, multiply the safe working load (SWL) of an individual wheel by three. This allows for only three wheels touching the rolling surface at any one time, often the case when the surface is uneven.
Other factors to consider when choosing the correct caster or wheel is the surface on which it is likely to run. Smaller casters can often be used if the surface is smooth (school halls for example) and they will meet the SWL requirements, but if you are having to roll equipment over rough ground then the bigger wheel is the way forward. Softer polyurethane tyres are more suitable on delicate floor surfaces and make a lot less noise, a consideration if working in a residential area. Good plating and a strong industrial finish are also essential if the equipment is to be used in a harsh environment, ball race running gear will help ease start resistance.
The most common style of caster or wheel used on flight cases or heavy sound and lighting equipment is the 4” or 100mm type often with a blue rubber or polyurethane tyre. The fixings for this style are fairly standard, with four bolts holding the caster in place, so if you are kitting out a lot of equipment standardizing in some way may be worth considering. If you are moving excessively heavy loads, then you will want to consider an industrial caster, there are all kinds of options available including iron wheels, that are more likely to withstand extreme conditions.