6221 bearing: complete specifications & equivalents
The 6221 is a ISO 15 radial bearing sized 105 x 190 x 36 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 105 mm |
| Outer diameter D | 190 mm |
| Width B | 36 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN / C3 available |
| Tolerance class | P0 |
| Cage | steel, stamped ribbon (J-type) |
| Basic dynamic load rating C | 140 kN |
| Basic static load rating C0 | 104 kN |
| Fatigue load limit Pu | 3.65 kN |
| Reference speed (thermal) | 7000 rpm |
| Limiting speed (mechanical) | 4500 rpm |
| Operating temperature | -40 to +150 °C |
| Mass | 3800 g |
| Manufacturer designation | SKF 6221 |
| Standard | ISO 15 |
| Catalog version | SKF PUB BU/P1 17000/1 EN (Oct 2018) |
| Last verified | 2026-09-25 |
Source: catalog reference (SKF PUB BU/P1 17000/1 EN (Oct 2018)) · extracted 2026-09-24
Parameters extracted from the official SKF Rolling Bearings catalogue (SKF PUB BU/P1 17000/1 EN (Oct 2018)); SKF® and SKF Explorer® are trademarks of AB SKF, used here for identification only — mpnbase is not an authorized SKF distributor. Boundary dimensions are ISO 15 interchangeable; current production values may differ, verify at skf.com.
Dimensions in inches & 6200-series range
| Bore d | 4.134 in |
|---|---|
| Outer diameter D | 7.48 in |
| Width B | 1.417 in |
| ISO bore code | 21 |
| Radial section height (D−d)/2 | 42.5 mm |
| Smallest bore in 6200-series | 3 mm |
| Largest outer diameter in 6200-series | 540 mm |
| Width range across 6200-series | 2.5–85 mm |
| Bore position in 6200-series (smallest first) | 30 of 45 |
| Bore above smallest 6200-series size | 102 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 6221-2RS | NSK | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 105×190×36 mm envelope per ISO 15; seal variant differs (OPEN vs 2RS) — confirm sealing suits the duty. |
| 6221-NSK | NSK | full Dimensions and internal design equivalent — standard interchange. | Identical ISO 15 envelope, seal and ratings band — standard interchange; re-verify precision class and clearance per supplier. |
| 6221-RSR | NSK | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 105×190×36 mm envelope per ISO 15; seal variant differs (OPEN vs RSR) — confirm sealing suits the duty. |
| 6221-ZZ-NSK | NSK | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 105×190×36 mm envelope per ISO 15; seal variant differs (OPEN vs ZZ) — confirm sealing suits the duty. |
| 6221-2RS-NTN | NTN | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 105×190×36 mm envelope per ISO 15; seal variant differs (OPEN vs 2RS) — confirm sealing suits the duty. |
| 6221-NTN | NTN | full Dimensions and internal design equivalent — standard interchange. | Identical ISO 15 envelope, seal and ratings band — standard interchange; re-verify precision class and clearance per supplier. |
| 6221-RSR-NTN | NTN | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 105×190×36 mm envelope per ISO 15; seal variant differs (OPEN vs RSR) — confirm sealing suits the duty. |
| 6221-ZZ-NTN | NTN | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 105×190×36 mm envelope per ISO 15; seal variant differs (OPEN vs ZZ) — confirm sealing suits the duty. |
| 7221 | SKF | verify Commonly quoted cross reference; confirm against the target catalog before ordering. | — |
Interchange levels: full standard interchange · partial verify parameters · verify manual confirmation required. Links resolve to the equivalent model's specification page where available.
How the 6221 model number is decoded
In the 6200-series (diameter series 2 of ISO 15) the last two digits encode the bore: 6221 carries bore code 21 = 105 mm. Outside diameter 190 mm and width 36 mm come from the ISO 15 boundary-dimensions general plan. With no seal suffix the bearing is open: no shields or seals are fitted and lubrication is supplied by the application. For normal-load mounting with a rotating inner ring on a 105 mm shaft, typical catalogue practice is a m6 shaft seat with an H7 housing bore — verify against the actual load direction and magnitude. In the SKF catalogue this open execution carries the bare designation; protected variants are ordered separately as -2Z and -2RSH.
Typical equipment & failure modes
Common applications
- large gearboxes
- industrial fans and blowers
- hoists and winches
- heavy conveyors
Known failure patterns
- contamination wear from dust and dirt ingress through the open arrangement
- lubricant starvation when no regreasing interval is maintained
- raceway smearing under marginal lubrication at start-up
- edge loading from shaft deflection or housing misalignment
Selection pitfalls — read before you substitute
- Large bores like the 105 mm of 6221 demand clean, burr-free seats; one raised burr under a ring this size cocks the bearing and concentrates load at the raceway edge, cutting life drastically.
- The 62xx light series is the default general-purpose section at 105 mm bore; before upgrading to a 6321 for extra capacity, confirm the housing accepts a 190 mm OD and 36 mm width — it is not a drop-in swap.
- Storage matters for open bearings: 6221 leaves the factory with rust preventive only, so clean it and apply the service grease at assembly even if the rings look oily from the wrapper.
- Open bearings tolerate the highest speeds in the 6200-series but need a defined regreasing interval; run-to-failure lubrication is the dominant cause of early failure in open 6221 units.
- The housing bore for the 190 mm OD should be round within IT7; an oval bore pinches the outer ring of 6221 and shows up later as two-point loaded raceway wear.
- Axial location must clamp the ring face, not the seal area: a shoulder or circlip bearing on the seal side of the 36 mm-wide ring of 6221 drags the lip and overheats it.
- The open 6221 needs external sealing and application-supplied lubrication; in the SKF catalogue the protected variants are separate order numbers 6221-2Z (shields) and 6221-2RSH (contact seals), not suffix-free 6221.
- The 140/104 kN ratings here are SKF Explorer-class figures from catalogue PUB BU/P1 17000/1 EN (Oct 2018); SKF can revise internal geometry and ratings without changing the designation, so treat the catalogue version and date as part of the specification and re-verify for critical drives.
Frequently asked questions
What are the dimensions of a 6221 bearing?
A 6221 deep-groove ball bearing has a 105 mm bore, 190 mm outer diameter and 36 mm width (4.134 × 7.48 × 1.417 in), per ISO 15 boundary dimensions. It is an open bearing with no seals or shields.
How does the 6221 bore code work?
The last two digits of 6221 are bore code 21, giving 21 × 5 = 105 mm bore. The 190 mm outside diameter and 36 mm width follow the ISO 15 diameter series, not the bore code alone.
What does no suffix on 6221 mean?
A bare 6221 designation means open: no shields or seals, normal CN radial clearance and P0 normal tolerance unless further suffixes are ordered. The application must supply and retain the lubrication.
How does the 6200 compare with other series at the same 105 mm bore?
The '2' is the light diameter series: 190×36 mm with a 42.5 mm radial section at 105 mm bore. A 6321 on the same bore is larger and higher-rated; a 6021 is smaller and lower-rated.
What is the SKF designation and catalogue data for 6221?
In the SKF Rolling Bearings catalogue this size is listed as 6221 — the open (unsealed) execution, 105×190×36 mm per ISO 15. Quoted values: C 140 kN, C0 104 kN, Pu 3.65 kN, limiting speed 4500 r/min, mass 3800 g. Brand suffixes (2Z, 2RSH, 2RSL) differ from the industry-neutral spelling 6221.
Reviewed & verified by the MPN Base engineering desk against source catalog SKF PUB BU/P1 17000/1 EN (Oct 2018) on 2026-09-25. Read our editorial & correction policy.