The right castor is not selected based on load capacity alone. Floor conditions, wheel diameter, overall height, wheel material, bearing type, travelling speed and environmental conditions also determine whether transport equipment runs easily, safely and reliably over the long term.
This selection guide leads you step by step to the right solution. If you know the weight, installation dimensions, floor and operating conditions, the required castor can usually be narrowed down quickly.
The key specifications at a glance
- Unladen weight of the unit and maximum payload
- Number and arrangement of the wheels or castors
- Required overall height and possible wheel diameter
- Floor conditions, edges and obstacles
- Manual or powered operation
- Travelling speed, travel distance and frequency of use
- Desired smooth running, damping and floor protection
- Temperature, moisture, chemicals, hygiene and ESD requirements
1. Determine application and travel path
Start with the application: is a machine only moved occasionally, does a trolley travel through production every day, or does the castor run permanently in a conveyor system? The more often, faster and longer a castor is moved, the more important an adequately large wheel diameter, high-quality bearing and suitable tread become.
Also check the travel path:
- Smooth industrial floors: hard treads provide low rolling resistance.
- Uneven floors, joints or thresholds: larger wheels and elastic treads reduce shocks.
- Sensitive floors: rubber or polyurethane distribute the load better and protect the surface.
- Outdoor areas: take corrosion protection, moisture and temperature changes into account.
2. Calculate load capacity per castor
For the design, the total weight made up of unladen weight and maximum payload is what matters. For a unit with four castors, a conservative calculation is often made in practice using only three load-bearing castors at the same time, because floor unevenness can temporarily unload one castor.
Guideline formula:
Required load capacity per castor = (total weight × safety factor) ÷ (number of castors − 1)
The safety factor depends, among other things, on the floor, speed, shock loads and frequency of use. You can find the full calculation with safety factors and an example under Correctly calculating the load capacity of wheels and castors.
If edges, shocks, falling loads or transverse forces also act, the design must include additional reserves. Read more under Loads on wheels and castors.
3. Determine the number and arrangement of castors
The arrangement affects manoeuvrability, tracking and operating force:
- Four swivel castors: very manoeuvrable and suitable for confined areas.
- Two swivel castors and two fixed castors: good straight-line travel with good manoeuvrability.
- Swivel castors with directional lock: manoeuvrable or tracking straight as required.
- Swivel castors with total lock brake: block wheel travel and swivel movement for secure standing.
You can find further design notes in the Mounting and fastening variants for castors. Suitable rigid versions can be found under fixed castors, braked versions under swivel castors with brake.
4. Select wheel diameter and overall height
A larger wheel diameter generally reduces rolling resistance and makes it easier to roll over joints, edges and small obstacles. At the same time, the overall height of the castor usually increases. Available installation space and the desired running properties must therefore be considered together.
- Very low overall height: check compact mini heavy-duty castors .
- Long travel distances or uneven floors: choose the largest possible wheel diameter.
- High load with limited space: compare not only the diameter, but also wheel width, material and bearing type.
5. Determine the right wheel material
| Material | Typical properties | Suitable for |
|---|---|---|
| Polyurethane | high load capacity, wear-resistant, floor-friendly, relatively quiet | industry, mechanical engineering, workshops and frequent travel movements |
| Rubber | very quiet, good damping, high grip | sensitive floors, low-noise transport and uneven travel paths |
| Polyamide | very low rolling resistance, high load capacity, hard and robust | smooth floors, high loads and dry industrial environments |
| Steel | extremely resilient, dimensionally stable, hardly any damping | the highest loads on durable travelling surfaces |
The hardness of the tread affects rolling resistance, damping and contact pressure. Hard wheels roll easily on smooth floors, but transmit shocks more strongly. Elastic treads run more quietly and protect the floor and transported goods.
6. Take bearing type and rolling resistance into account
In addition to material and diameter, the wheel bearing affects how easily a castor moves:
- Plain bearing: simple, robust solution for low speeds and short distances.
- Roller bearing: easy running and suitable for many transport applications.
- Ball bearing: low rolling resistance, precise running and suitable for frequent or faster movement.
Technical background can be found under Starting and rolling resistance of wheels and castors. For swivel castors, the swivel resistance is also important.
7. Select the fastening type
The fastening must suit the design and load:
- Top plate: stable, wide-area force transfer; often used with industrial and heavy-duty castors.
- Bolt hole: compact mounting with a central bolt.
- Stem or threaded stem: quick mounting on equipment, furniture and tube constructions.
In addition to the bolt pattern, also compare plate size, screw diameter, overall height and possible interfering contours. The available variants are summarised under correctly mounting and fastening castors .
8. Define manoeuvrability and brakes
A brake is required when trolleys, workstations or machines must be positioned securely. A wheel brake blocks only the wheel. A total lock brake also blocks the swivel movement of the swivel castor. Directional locks fix the castor in one travel direction and improve the straight-line running of longer trolleys.
With high loads, large dimensions or frequent changes of direction, the operating force must also be taken into account. Large wheels, suitable trail and crowned treads can make swivelling easier.
9. Assess ride comfort, noise and floor protection
Quiet running and low vibrations are particularly important for workshop trolleys, stage equipment, sensitive goods and travel over joints. Elastic materials such as rubber or polyurethane damp shocks better than hard wheels made of polyamide or steel.
How tread, hardness and contact pressure interact is explained on the page Damping and resilience of wheels and castors.
10. Check environment, hygiene and safety
Special environmental conditions can limit material, housing and bearing type:
- Hygiene and moisture: check easy-to-clean materials and stainless steel castors .
- Contact discolouration: choose a non-marking tread.
- Chemicals: check the resistance of the wheel, bearing, seal and housing individually.
- High or low temperatures: use suitable temperature-resistant wheels and castors .
- Electrostatic charge: select antistatic or electrically conductive castors .
Further information on cleaning, contact discolouration and corrosion can be found under Hygiene and cleanliness of wheels and castors.
11. Select the right product group
- All wheels and castors – overall overview by design and application
- Industrial castors – for production, logistics and transport equipment
- Mini heavy-duty castors – high load capacity with low overall height
- Heavy-duty castors – for machines, systems and high to extreme loads
- Stainless steel castors – for moisture, hygiene and outdoor areas
- Swivel castors with brake – move freely and position securely
12. Example: selecting a castor for a workshop trolley
A workshop trolley weighs 400 kg including maximum payload and stands on four castors. It is moved regularly by hand over a normal industrial floor with small joints.
- Total weight: 400 kg
- Number of castors: 4
- Safety factor for normal industrial conditions: for example 1.5
- Calculation: (400 kg × 1.5) ÷ (4 − 1) = 200 kg per castor
Each castor should therefore support at least 200 kg. A sufficiently large wheel diameter can help make it easier to roll over joints. A polyurethane tread combines load capacity, floor protection and smooth running. Two swivel castors with total lock brake and two fixed castors provide a combination of manoeuvrability, straight-line travel and secure standing. The final choice depends on overall height, travel path and the desired level of operating comfort.
Are you unsure about the selection?
Send us the key operating data. We will check the application and recommend a suitable standard castor or special solution.
- Total weight and number of castors
- Required wheel diameter and maximum overall height
- Floor conditions and possible obstacles
- Travelling speed and frequency of use
- Temperature, moisture, chemicals or ESD requirements
- Required fastening and brake type
Frequently asked questions about castor selection
How is the load capacity of a castor calculated?
Add the unladen weight and maximum payload. Then take into account the number of castors that actually bear the load as well as a safety factor for floor, shocks and operating conditions. With four castors, a conservative calculation often uses three load-bearing castors.
Which wheel material rolls particularly easily?
On smooth, hard floors, hard materials such as polyamide usually have very low rolling resistance. Polyurethane offers a balanced compromise between smooth running, high load capacity, wear resistance and floor protection.
When should a larger wheel diameter be chosen?
Larger wheels are useful for longer travel distances, floor joints, thresholds or uneven surfaces. They generally reduce the force required to push, but need more installation space and often increase overall height.
When are swivel castors and when are fixed castors useful?
Swivel castors allow changes of direction and high manoeuvrability. Fixed castors provide straight-line tracking. Many transport trolleys combine two swivel castors with two fixed castors. Four swivel castors are particularly manoeuvrable, but can be more difficult to guide over longer straight distances.