Definition: Side load capacity is the ability of a caster to withstand horizontal forces applied perpendicular to the direction of travel.
What it affects: Swivel integrity, bearing life, frame deformation, and overall durability.
Why side load capacity matters
Casters rarely experience purely vertical loading. Turning, impacts, and misalignment introduce significant side loads.
- Occurs during sharp turns and direction changes
- Increases during impacts with obstacles
- Common in powered carts and AGVs
- Accelerates wear in swivels and bearings
Reality: Many caster failures are caused by side loading, not vertical overload.
Common sources of side loading
- Forklift impacts or manual collisions
- Uneven floors causing lateral force spikes
- High-speed turns
- Rigid frames that do not allow caster alignment
Design factors that affect side load capacity
| Design factor | Impact on side load capacity |
|---|---|
| Kingpin vs kingpinless | Kingpinless designs handle side loads better |
| Fork thickness | Thicker forks resist bending |
| Swivel bearing type | Precision bearings distribute lateral forces |
| Wheel width | Wider wheels improve lateral stability |
Common engineering mistakes
- Assuming vertical load rating covers side loads
- Using kingpin designs in high side-load environments
- Ignoring lateral forces in powered equipment
- Underestimating shock-induced side loads
Rule: If side loading is expected, select casters designed specifically for lateral force resistance.
FAQs
Is side load capacity published by manufacturers?
Rarely. It is often application-dependent and must be evaluated by design.
Do larger wheels reduce side loading?
They can reduce impacts but do not eliminate lateral forces.
Are kingpinless casters required for side loads?
They are strongly recommended in high side-load applications.
How can I reduce side loading?
Use larger wheels, increase offset, improve frame alignment, and reduce speed.