Bearing Data Glossary
Plain definitions of bearing dimension symbols, load ratings, clearance classes, seal and shield codes and bearing types, with the ISO standard each comes from.
published bearingsglossary
Plain definitions of the symbols, ratings, suffixes and bearing types that appear in bearing product data, with the ISO standard each comes from. Use it alongside why multi-brand bearing catalogs break.
| Term | Symbol | Meaning | Applies to | Standard |
|---|---|---|---|---|
| Bore diameter | d | Inner diameter of the bearing, the shaft fit | All bearings | ISO 15, ISO 104 |
| Outside diameter | D | Outer diameter, the housing fit | All bearings | ISO 15, ISO 104 |
| Width | B | Width of the inner ring of a radial bearing | Radial bearings | ISO 15 |
| Total width | T | Assembled width of a tapered roller bearing, cone and cup together | Tapered roller | ISO 355 |
| Cup width | C | Width of the outer ring (cup) of a tapered roller bearing | Tapered roller | ISO 355 |
| Cone | — | Inner ring of a tapered roller bearing, with rollers and cage | Tapered roller | — |
| Cup | — | Outer ring of a tapered roller bearing | Tapered roller | — |
| Height | H | Overall height of a thrust bearing | Thrust bearings | ISO 104 |
| Basic dynamic load rating, radial | Cr | Constant radial load giving a rated life of one million revolutions | Radial bearings | ISO 281 |
| Basic dynamic load rating, axial | Ca | The axial equivalent, for thrust bearings | Thrust bearings | ISO 281 |
| Basic static load rating | C0r / C0a | Load causing a set permanent deformation at the most loaded contact | All bearings | ISO 76 |
| Limiting speed | — | Highest recommended speed, usually given for grease and for oil | All bearings | — |
| Radial internal clearance | C2, CN, C3, C4, C5 | Free radial play between rings; CN is normal, C3 larger | Radial bearings | ISO 5753-1 |
| Shield | Z, 2Z, ZZ | Non-contact metal cover; one side (Z) or both | Ball bearings | — |
| Contact seal | RS, 2RS, DDU, LLU | Rubber seal touching the inner ring; one side or both | Ball bearings | — |
| Deep groove ball bearing | 6xxx | General-purpose radial ball bearing | — | ISO 15 |
| Self-aligning ball bearing | 1xxx, 2xxx | Two ball rows, spherical outer raceway, tolerates misalignment | — | ISO 15 |
| Tapered roller bearing | 3xxxx | Takes combined radial and axial load, mounted in pairs | — | ISO 355 |
| Spherical roller bearing | 2xxxx | Two roller rows, self-aligning, high radial load | — | ISO 15 |
| Thrust ball bearing | 5xxxx | Takes axial load only | — | ISO 104 |
| Crossed roller bearing | — | Rollers alternately crossed between rings, takes load in every direction | Precision motion | — |
| Interchange / cross-reference | — | A confirmed pairing of part numbers from different makers for the same specification | All bearings | — |
| Series | — | A maker’s grouping of bearings that share design and dimension rules | All bearings | — |
| Not applicable vs missing | — | A blank that is correct for the bearing type, versus a value that exists but was never captured | Product data | — |
Related
Guide
Why multi-brand bearing catalogs break
Dimensions, blanks and equivalence in one view.
Guide
Width B, T or H
The dimension labels that break your filters.
Guide
Blank, not applicable, or wrong
Measuring completeness on bearing data.
Guide
Is it the same bearing?
Cross-brand equivalence before you compare price.
Claro
See how Claro handles this in production
This concept is one piece of keeping a catalog trusted. See how Claro resolves identity, enriches missing attributes, and validates every update before it reaches your PIM or ERP.
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