How caster load classes are defined
A caster's load class is set by its dynamic load rating — the load it carries while moving — not by how much it holds standing still. Static capacity is always higher, which is why a caster that holds a loaded rack in the workshop can still fail within weeks on a trolley that moves the same load all day. Ratings also assume the load is shared: on a four-caster cart, size for three casters carrying the load, not four, because floors, debris and acceleration mean the load never splits evenly.
Our catalog spans 30 kg to 2,000 kg per caster. That range is covered by named series — RM-Medium (150–500 kg), RM-Heavy (500–1,500 kg) and RM-Extreme (1,500 kg and above) — plus light-duty families below 150 kg. The full arithmetic, including the divide-by-three rule and safety factors by floor and speed, is in how to calculate caster load capacity.
Light duty: up to 150 kg per caster
Light-duty casters move equipment that is pushed by hand most of the day: office equipment, light trolleys, display units and medical carts. At this band the deciding factors are usually noise, floor protection and rolling ease rather than bracket strength. Rubber caster wheels (typical loads 30–400 kg per caster) absorb shock and run quietly on hard floors, and silent and elastic casters (40–300 kg) are built specifically for indoor equipment where noise is a requirement, not a preference.
Medium duty: 150–500 kg per caster
Medium duty covers platform trucks, warehouse trolleys and light industrial equipment — loads one person still steers by hand, but heavy enough that wheel material starts to affect push force. Polyurethane caster wheels carry more load than rubber at the same size while protecting floors, and nylon (PA6) casters take the same band with better resistance to water and many chemicals where floors are wet or washed down. When the environment — not the load — is the constraint, stainless steel casters (load classes from 60 kg to 1,500 kg per caster) span this band and above for food, pharmaceutical and washdown use.
Heavy duty: 500–1,500 kg per caster
From roughly 500 kg per caster the bracket, not the wheel, becomes the component to specify: welded steel construction, larger top plates and precision or double-row ball bearings. Heavy duty casters (500–2,000 kg per wheel) are built exactly for this band — machinery moving, dies and heavy trolleys — with every bracket load-tested on dynamic rigs before assembly. Rigid (fixed) casters carry more load than same-size swivels because the fixed raceway removes a moving part, which is why heavy trolleys typically pair two rigid and two swivel casters.
Extreme duty: 1,500 kg and above per caster
Above 1,500 kg per caster, only forged construction and steel-wheel options remain sensible. Forged steel caster wheels go up to 2,000 kg per caster for extreme loads and harsh floors, where the forging process gives the bracket the impact strength a casting or a stamped plate cannot. At this band, floor condition and speed matter as much as the raw rating: wheel diameter and floor type decide whether the rating survives contact with an uneven or debris-strewn floor.
Load class comparison at a glance
The table condenses the four bands. Every range shown is the family's own stated range on its product page — follow the links for wheel materials, mounting dimensions and environment options.
| Load class | Typical per-caster load | What to verify before ordering | Fitting families |
|---|---|---|---|
| Light duty | up to 150 kg | Noise, floor protection, rolling ease by hand | Rubber (30–400 kg), silent and elastic (40–300 kg) |
| Medium duty | 150–500 kg | Push force, floor type, wet or chemical exposure | Polyurethane, nylon (PA6), stainless (60–1,500 kg) |
| Heavy duty | 500–1,500 kg | Welded brackets, bearing type, mounting plate size | Heavy duty (500–2,000 kg), rigid casters, stainless |
| Extreme duty | 1,500 kg and above | Forged construction, floor condition and speed, towed use | Forged steel (up to 2,000 kg), heavy duty |
Verify the rating before you order
Whichever band you land in, three checks prevent most sizing mistakes. First, confirm the rating is a dynamic rating at a stated speed — ask which standard the figure was tested to. Second, size for three of four casters carrying the load, then apply a safety factor from your floor and duty cycle. Third, derate for the environment: temperature, floor debris and washdown all move the effective rating down. The load capacity calculation walks the arithmetic, and the material selection chart narrows the wheel material once the band is fixed. When a supplier quotes a figure without a test basis, make the test method part of the RFQ.