30221U bearing: complete specifications & equivalents
The 30221U is a ISO 355 radial bearing sized 105 x 190 x 39 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 105 mm |
| Outer diameter D | 190 mm |
| Width B | 39 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 320 kN |
| Basic static load rating C0 | 380 kN |
| Fatigue load limit Pu | 41 kN |
| Limiting speed (mechanical) | 1900 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 4450 g |
| Manufacturer designation | NTN 30221U |
| Standard | ISO 355 |
| Catalog version | NTN Ball and Roller Bearings CAT.No.2203E |
| Last verified | 2026-10-01 |
Source: catalog reference (NTN Ball and Roller Bearings CAT.No.2203E) · extracted 2026-10-01
Parameters extracted from the official NTN Ball and Roller Bearings catalogue (NTN Ball and Roller Bearings CAT.No.2203E); NTN® is a trademark of NTN Corporation, used here for identification only — mpnbase is not an authorized NTN distributor. Boundary dimensions are ISO 15 interchangeable; current production values may differ, verify at ntnglobal.com.
Dimensions in inches & 30200-series range
| Bore d | 4.134 in |
|---|---|
| Outer diameter D | 7.48 in |
| Width B | 1.535 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 42.5 mm |
| Smallest bore in 30200-series | 15 mm |
| Largest outer diameter in 30200-series | 580 mm |
| Width range across 30200-series | 11.75–104 mm |
| Bore position in 30200-series (smallest first) | 21 of 37 |
| Bore above smallest 30200-series size | 90 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 30221U | ISO 15 | full Dimensions and internal design equivalent — standard interchange. | ISO 15 boundary-dimension envelope; standard interchange — confirm clearance class and precision with the supplier. |
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 30221U model number is decoded
The NTN 2203E table prints 30221U in the standard-section 30200 family: 105 mm bore, 190 mm cup OD, 39 mm T, with a grease limiting speed of 1,900 r/min and an oil-lubricated ceiling of 2,500 r/min. The last two digits 21 are the ISO bore code, ×5 = 105 mm (codes 00–03 use the 10/12/15/17 exception table) under the ISO 355 numbering; the 39 mm value printed here is T, the width of the fully assembled cone-plus-cup set, not the inner-ring width alone. Suffix reading on 30221U: U marks the reinforced/uprated internal design of the bare number, a separate order number with higher load capacity than the basic execution; the suffix is part of the order number and the variants are not interchangeable articles. The two speed columns differ by a factor of .76 (grease/limiting 1,900 vs oil 2,500 r/min); heat generation at the cone rib decides which lubrication a real 30221U arrangement can sustain. With a rotating shaft a m6/n6 shaft seat and a press-fit cup are typical catalogue practice for 30221U; reverse the logic if the cup rotates, and re-verify against load direction and magnitude.
Typical equipment & failure modes
Common applications
- paper-machine press-section rolls
- large agricultural and forestry machine axles
- heavy industrial gearboxes and crane travel drives
- rolling-mill auxiliary and pinion-stand shafts
Known failure patterns
- cone-raceway spalling at the large rib when preload is set too high for the lubricant film
- flaking on one cone only when a back-to-back / face-to-face pair is loaded unevenly by a bent shaft
- smearing on the roller large ends and cone rib after a dry start with preload but no oil film
- pressed-steel cage pocket wear from roller skid at light radial load and high speed
- rolling-contact fatigue after the catalogue L10 life at the actual combined load
Selection pitfalls — read before you substitute
- Mount the 105 mm cone by induction heating (max 120 °C) and the cup with a press sleeve; the 4450 g ring mass makes cocking during fitting a direct raceway-brinelling risk.
- The standard-section 30200 family at 105 mm bore (190×39 mm assembled) carries more capacity than the lighter 320/329 sections but generates more preload heat; confirm oil availability before running near the 2,500 r/min oil ceiling.
- Back-to-back and face-to-face arrangements react differently to shaft bending: pick the pair orientation for the moment load before locking the 105 mm shoulder geometry, because retrofitting flips the cups.
- Grease packs must leave free volume in the 39 mm-wide set; over-greasing a paired bearing churning at the 2,500 r/min oil-band speed raises temperature and destroys the preload setting.
- ISO 355 makes the 105×190 mm envelope interchangeable but not the ratings: NTN prints 320/380 kN for this execution, and a cheaper same-number part can differ in roller complement and steel.
- The 320/380 kN ratings and 41 kN Pu here are NTN Ball and Roller Bearings CAT.No.2203E figures for 30221U (ISO 355 3FB); internal geometry legitimately differs between manufacturers, so re-verify ratings, adjustment and suffix before substituting another make on a rated drive.
Frequently asked questions
What are the dimensions and catalogue ratings of NTN 30221U?
30221U is a metric 4T tapered roller bearing to ISO 355: 105 mm bore, 190 mm outside diameter and 39 mm assembled width T (4.134 × 7.48 × 1.535 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 320 kN, C0 380 kN, Pu 41 kN, grease limiting speed 1,900 r/min, oil speed 2,500 r/min, mass about 4450 g. It is an open, separable cone/cup bearing with a pressed-steel cage.
What does the 4T prefix mean on 30221U?
4T is NTN's tapered roller bearing brand mark, stamped on the cone and cup in the factory. It identifies the NTN 4T programme and is not a dimension, so the catalogue and this page list the bare ISO 355 number (30221U); the lower-case 4t- factory spelling of the code is retained among the search aliases.
How does the 30221U designation encode the 105 mm bore and what is 3FB?
last two digits 21 are the ISO bore code, ×5 = 105 mm (codes 00–03 use the 10/12/15/17 exception table). The 190 mm OD and 39 mm assembled T follow the ISO 355 dimension-series plan. 3FB is the maker-neutral ISO 355 abbreviation for this dimension series (the same code other manufacturers print); 4T is NTN's own brand mark.
Why does 30221U list two speeds, 1,900 and 2,500 r/min?
The lower figure, 1,900 r/min, is the grease-lubricated limiting speed — the mechanical ceiling for the cage, rollers and cone-rib contact. With oil lubrication NTN rates 30221U at 2,500 r/min because oil removes rib-contact heat better. Real limits still depend on preload, oil flow and cooling.
What does the suffix on 30221U mean?
Suffix reading on 30221U: U marks the reinforced/uprated internal design of the bare number, a separate order number with higher load capacity than the basic execution; the suffix is part of the order number and the variants are not interchangeable articles.
Reviewed & verified by the MPN Base engineering desk against source catalog NTN Ball and Roller Bearings CAT.No.2203E on 2026-10-01. Read our editorial & correction policy.