Dynamic load capacity

The load capacity stated for a wheel or caster is the load capacity that that wheel or caster could withstand during a test on a rotating bench according to DIN EN 12527-12533 (ISO 22878-22884).

To determine the required load capacity of a wheel or caster, it is important to know the own weight of the means of transport, the maximum additional weight and the number of supporting wheels or castors. When using four or more wheels or castors, the load on each individual wheel or caster may vary. The required load capacity is calculated as follows:

 

        T = required load capacity per wheel or castor E = own weight of the means of transport Z = maximum additional weight n = number of supporting wheels or castors S = safety factor    

Wheels and castors with ball bearings can reach speeds of over 4 km/h with a reduced load capacity.

 

Recommended safety factors for different applications

The safety factor S is used to account for deviations from standard application conditions (smooth surface, walking speed of 2.5 mph (4 km/h), equal load distribution, driving straight ahead, ambient temperature between +15 °C and +28 °C). The safety factor is influenced by the speed of movement and the ratio of wheel size to obstacle height. There are four different categories (see table).

Safety factors do not take into account tread wear.

 

Determination of the safety factor S

Transport	Environment	Obstacle height	Safety factor
manually	within	< 5 % of wheel size	1.0-1.5
manual	outside	> 5 % of the wheel size	1.5-2.2
motorised	inside	< 5 % of wheel size	1.4-2.0
motorised	outside	> 5 % of wheel size	2.0-3.0