Castors consist of a bracket and at least one wheel. Brackets for castors are available in different versions. There are two general categories:
Swivel castors (swivelling fork)
Fixed castors (fixed fork)
Castors – selection criteriaThe following selection criteria must be observed when selecting castors:
- Load capacity
- Tread material
- Wheel Ø, starting and rolling resistance
- Bearing type
- Environmental factors, temperature, chemistry and corrosion
For more information, refer to our Wheel and castor guide.
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Get an overview of the castors offered by Blickle in our product range.
Determining the required load capacity for castorsThe required load capacity for castors is calculated using the weight of the transport unit and its load, divided by the number of load-bearing castors. The result is multiplied by a safety factor dependent on the standard conditions:
T = Load capacity per castor
E = Weight of the transport unit
Z = Maximum load
n = Number of load-bearing castors
S = Safety factor
For castors, the safety factor S takes into consideration deviations from the standard conditions (smooth floor, walking speed, uniform load distribution, travelling straight, ambient temperature from +15°C to +28°C). In addition to the speed, the safety factor is influenced by the ratio of the wheel Ø to the height of the obstacle. The greater the deviation from the standard conditions, the greater the factor S that must be selected.
A differentiation is made between four standard conditions:
Manual movement for indoor use:
(height of the obstacle < 5% of the wheel Ø): safety factor: 1.0 to 1.5
Manual movement for outdoor use:
(height of the obstacle > 5% of the wheel Ø): safety factor: 1.5 to 2.2
Motor-driven movement for indoor use:
(height of the obstacle < 5% of the wheel Ø): safety factor: 1.4 to 2.0
Motor-driven movement for outdoor use:
safety factor: 2.0 to 3.0
For castors with ball bearings, speeds over 4 km/h are possible with a simultaneous load capacity reduction. If a wheel or fixed castor is primarily subjected to static loads, a load capacity increased by up to 25% can be assumed. In the event of long endurance times under high loads, the risk of the wheel tread flattening must be taken into account.
Starting, rolling and swivel resistance of castorsThe starting and rolling resistance of castors is significantly influenced by the condition of the floor, total load, wheel Ø, deformation and treat type, as well as the bearing type.
The swivel resistance is influenced by the following factors:
- Tread & tyre hardness
The manoeuvrability of a transport unit depends on the number, type and arrangement of the castors. These factors in turn influence the load capacity, mobility, control, turning radius and capsizing stability of a trolley.
Castors – useful links:Wheel and castor guide