Correctly calculate the load capacity of wheels and castors

The load capacity per wheel or castor is one of the most important parameters when designing transport trolleys, industrial trucks and conveyor technology. Only when the load capacity is calculated correctly will wheels and castors operate safely and with low wear in the long term.

What does load capacity per wheel mean?

Load capacity indicates which load a single wheel or castor can carry continuously under defined conditions. Important: in practice, not only the pure load but also factors such as floor condition, travel speed, impacts and temperature have an effect.

Basic formula for calculation

Typically, the following calculation is used:

Required load capacity per wheel = (total weight × safety factor) / (number of wheels − 1)

• Total weight = dead weight of the trolley + payload
• Safety factor = depends on floor, impacts and frequency of use
• (Wheels − 1) = conservative assumption that one wheel is temporarily unloaded

Recommended safety factors

• 1.3 – 1.4: smooth floor, quiet running, low speed
• 1.5 – 1.7: normal industrial conditions, slight unevenness, occasional impacts
• 1.8 – 2.0: poor floors, frequent impacts, continuous use, higher speed

Example calculation

A trolley weighs 80 kg and is also to carry 320 kg. In total there are 4 swivel castors, used in a normal workshop environment.

Total weight = 80 kg + 320 kg = 400 kg
Safety factor = 1.5
Number of wheels = 4

Required load capacity per wheel = (400 kg × 1.5) / (4 − 1) = 600 / 3 = 200 kg per wheel

In this case, wheels with at least 200 kg load capacity per castor should be selected – preferably slightly higher, e.g. 220–250 kg, to allow for reserves.