Dynamic Load Capacity

The dynamic load capacity is a crucial consideration for transport equipment. It refers to the maximum weight a castor or wheel can bear while repeatedly in motion for an extended period.

To determine the load capacity that a wheel or castor needs, it is essential to know the dead weight of the transport equipment, the maximum additional weight and the number of supporting wheels or castors. The load on each wheel or castor may vary when using four or more wheels or castors.

The dynamic load capacity T per castor is calculated using the following formula:

T = (E + Z) / (n-1) x S

E = Dead weight of the equipment
Z = Payload
n = Number of castors or wheels
S = Safety factor

 Safety Factor

The safety factor is influenced by the speed and the ratio between wheel diameter and height of the obstacles and consists of 4 categories:

Indoor manual transport: (height of the obstacles < 5 % of the wheel Ø): Safety factor: 1.0 to 1.5

Outdoor manual transport: (height of the obstacles > 5 % of the wheel Ø): Safety factor: 1.5 to 2.2

Indoor power-driven transport: (height of the obstacles < 5 % of the wheel Ø): Safety factor: 1.4 to 2.0

Outdoor power-driven transport: Safety factor: 2.0 to 3.0

The calculation of load capacity is based on standard operating conditions. These conditions include moving straight ahead on level floors at walking speed with a uniform load distribution and a moderate ambient temperature. The load capacity will also vary if the actual conditions differ from these standard conditions. It would be best to consider the actual conditions from the outset, especially when it comes to heavy-duty castors that carry heavy loads; adding a safety factor to the formula is essential.

Please remember that safety factors do not consider the wear and tear of the wheel’s tread. Wheels and castors equipped with ball bearings can handle speeds higher than 4 km/h, even with reduced load capacity. If a wheel or a fixed castor is mainly subjected to static loads, it can bear up to 25% more weight. However, if a wheel or castor is under high loads for an extended period, there’s a risk of the tread flattening.

When calculating the load capacity of transport equipment, it is important to take into account that the equipment is often used on uneven floors. As a result, not all of the castors or wheels may bear the load at the same time. To address this issue, the load capacity calculation reduces the number of castors or wheels by one in order to ensure that the equipment can handle the load even in such cases.