Recommended Load Capacity of Castors: Key Considerations
When selecting castors, it’s essential to understand that load capacities are rated per individual castor, not for the complete set.
How to Calculate Castor Load Capacity
To determine the appropriate castor load rating for your application, use the calculation method aligned with your castor configuration. This ensures the system can safely support the total gross weight—which includes both the weight of the transport equipment and the maximum payload.
⚠️ Unless otherwise stated, all load capacities refer to manual movement (hand-pushed) at walking speed (up to 4 km/h). For power-towed applications, use castors specifically engineered for that purpose.
Factors Affecting Load Capacity
Several variables can impact the actual load each castor must bear:
- Floor Imperfections: Cracks, joints, kerbs, potholes, or drainage gullies may cause shock loads.
- Uneven Surfaces: Certain castor configurations can result in some castors lifting off the ground, transferring more weight to the remaining ones.
- Loading Method: Dropping loads onto equipment—even from a low height—can introduce shock loads and momentarily increase weight stress on individual castors.
To ensure safety and durability, always factor in a safety margin when calculating load capacity.
Load Capacity by Castor Configuration
A castor configuration refers to the number, type, size, and arrangement of castors fitted to a piece of equipment such as a trolley, cart, or platform. The configuration affects how the equipment handles weight, moves, and responds to floor conditions.
Common castor configurations include:
- Four-castor setup (typically two swivel – perhaps braked – and two fixed castors)
- Three-castor layout (used for lightweight, compact designs and usually a circular platform)
- Six-castor configurations with the 2 central castor being larger to provide a central pivoting function.
The right castor configuration ensures optimal load distribution, manoeuvrability, and stability, especially on uneven or industrial floors.
4-Castor Configuration (Standard Setup)
- Each castor must support at least one-third (33%) of the total gross weight:
- Formula: (Transport Equipment Weight + Maximum Load) ÷ 3
3-Castor Configuration (Light Loads Only)
Each castor must carry at least 40% of the total gross weight.
⚠️ This setup is suitable only for lightweight trolleys.
6-Castor Configuration with Central Fixed Castors
This configuration features two central fixed castors that are slightly taller—either by size or with packing plates (typically 25mm extra height).
Used for long platform trolleys to enhance manoeuvrability and control.
- Central fixed castors: Must each support at least 50% of the gross weight
- Other castors: Should support at least 33% of the gross weight
Jacking Castors & Footmaster KGD Levelling Castors
These are designed to lift and level equipment.
- Each castor must support at least 50% of the total gross weight:
- Formula: (Transport Equipment Weight + Maximum Load) ÷ 2
This is because the lifting and lowering operation of Jacking and Footmaster Levelling castors means that each castor can be subjected to half the total gross weight.
Summary
When choosing castors, always:
- Calculate load per castor, not per set.
- Include transport weight and maximum load in your calculations.
- Factor in surface conditions, castor configuration, and shock-loading scenarios.
- Use specialised castors for powered or levelling applications.
By following these guidelines, you’ll ensure safe, efficient, and long-lasting performance from your castors.
If in doubt, please call us on 0121 772 1010 and speak to one of our sales team (Mon – Fri: 8:30am to 5:00pm)
