In order to determine the number of castors or wheels you will require, several factors must be taken into account: unloaded weight, maximum load, number of castors or wheels and working conditions.

The working conditions, floor surfaces and conditions are very important elements that must be taken into consideration when calculating the load capacity. This is especially true of uneven and rough surfaces which can easily overload three of the tour castors.

With this in mind, a definition of standard conditions would be a surface on which castors are not overloaded, receive no impacts and which is smooth, non-abrasive and free of obstacles, cracks, grooves, doorjambs, nails, etc.

Load Capacity of Casters

In order to guarantee the quality of our industrial castors and the adjustment to each necessity, Alex castors and wheels uses the load capacity formula:

  • C: Required load capacity of the castor or wheel
  • P: Dead Weight of the transit unit
  • M: Maximum additional Load
  • N: Number of castors or wheels
  • S: Safety factor

The safety factor is used when conditions vary from standard. This varies from 1•3 to 2 depending on the actual conditions encountered.

All load capacities in this catalog have been calculated according to European Materials Handling Standards: EN 12528 and EN 12533.


The following symbols have been used in the catalogue and search engine so as to make interpretation of technical specifications easier and quicker:

Load capacity
Axle hole
Width of tyre
Length of hub
Wheel diameter
Size of plate
Distance between holes
Plate hole diameter
Bolt hole diameter
Overall height
Width x height of stem or hilt
Plain bearing
Roller bearing
Ball bearing
Tapered roller bearing
The choice of the number and configuration of the wheels depends on the specifications of the load to be transported and surface over which it is to be moved. The main ones are:

2 swivel castors and 2 fixed castors

Industrial applications. They are easily manoeuvrable for medium loads over long distances. Maximum Load Capacity = Total Load/3

4 fixed castors central pivoting

For medium- heavy loads. Good straight travelling and relatively easy manoeuvrability. The two central fixed castors are used to pivot on when manoeuvring. Castors can be replaced by wheels on a central axle. Maximum Load Capacity = Total Load/2.

2 swivel castors and 2 fixed castors in the centre

Good load capacity and manoeuvrability in small spaces. Fixed castors can be replaced by a one wheel set. Maximum Load Capacity = Total Load/2

4 swivel castors

Good load capacity and excellent manoeuvrability in all directions. Not for use over long distances or uneven surfaces. Maximum Load Capacity = Total Load/2

1 swivel castor and 2 fixed castors

For use with light loads for manoeuvrable trolleys. Weight should be evenly distributed on a small appliance. Maximum Load Capacity =Total Load/3.

4 swivel castors and 2 fixed castors in the centre

Ideal for large trolleys and heavy loads.Trolleys should have a strong base and will turn on the centre castors. Maximum Load Capacity = Total Load/2.

3 swivel castors

First-rate manoeuvrability. Recommended for drums and barrels and light trolleys. Maximum Load Capacity = Total Load/3.