30211-NTN bearing: complete specifications & equivalents
The 30211-NTN is a ISO 355 radial bearing sized 55 x 100 x 22.75 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 55 mm |
| Outer diameter D | 100 mm |
| Width B | 22.75 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 103 kN |
| Basic static load rating C0 | 111 kN |
| Limiting speed (mechanical) | 3600 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 725 g |
| Manufacturer designation | NTN 30211 |
| 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 | 2.165 in |
|---|---|
| Outer diameter D | 3.937 in |
| Width B | 0.896 in |
| ISO bore code | 11 |
| Radial section height (D−d)/2 | 22.5 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) | 11 of 37 |
| Bore above smallest 30200-series size | 40 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 30211 | SKF | 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. |
| 30211-DF | SKF | verify Commonly quoted cross reference; confirm against the target catalog before ordering. | Model-number interchange per ISO 15; confirm dimensions, sealing and ratings in the supplier catalogue. |
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 30211-NTN model number is decoded
30211 is the NTN 4T catalogue entry for a 55×100×22.75 mm metric tapered roller bearing — separable cone and cup, designed for combined radial and axial load as an individually adjusted bearing. On the NTN nameplate the parts carry 4T plus the bare code, while 2203E orders 30211 by the metric ISO 355 number (ISO series abbreviation 3DB): 55 mm bore, 100 mm OD. With no letter after the number, 30211 is the basic open 4T execution: steel cage, normal adjustment, no seal or special internal-design suffix in the order code. Imperial cross-check for the drawing: 55×100×22.75 mm is 2.165 × 3.937 × 0.896 in; ISO 355 makes the envelope interchangeable but C/C0, 103/111 kN, is NTN-specific. Open 4T bearings need application seals; without them the grease at the cone rib of 30211 washes out and the rib/roller-end contact smears on the first wet or dusty shift.
Typical equipment & failure modes
Common applications
- pump and compressor drive shafts carrying combined load
- machine-tool gearbox and headstock shafts
- axle final-drive and differential positions
- construction-equipment wheel and pivot hubs
Known failure patterns
- cup creep and housing fretting when the specified outer-ring press fit is not achieved
- smearing on the roller large ends and cone rib after a dry start with preload but no oil film
- flaking on one cone only when a back-to-back / face-to-face pair is loaded unevenly by a bent shaft
- cage damage from a mounting blow delivered through the roller complement instead of the ring face
- indentation of the raceways by hard particles in unsealed open arrangements
Selection pitfalls — read before you substitute
- Hub and pinion bearings of this 55 mm bore class are commonly adjusted in pairs; verify end play against the axle drawing and re-torque after bedding-in rather than trusting the initial preload on 30211.
- The standard-section 30200 family at 55 mm bore (100×22.75 mm assembled) carries more capacity than the lighter 320/329 sections but generates more preload heat; confirm oil availability before running near the 4,900 r/min oil ceiling.
- The U/UTG/X/C/CA/D suffix variants of a base number share the bore but not the article: ordering 30211 by size alone can deliver the wrong contact-angle execution for a pinion position.
- Do not confuse T (22.75 mm assembled width of cone + cup) with the cone width when drawing spacers; an abutment sized to T instead of the ring width leaves the cup unseated.
- ISO 355 makes the 55×100 mm envelope interchangeable but not the ratings: NTN prints 103/111 kN for this execution, and a cheaper same-number part can differ in roller complement and steel.
- The 103/111 kN ratings here are NTN Ball and Roller Bearings CAT.No.2203E figures for 30211 (ISO 355 3DB); 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 30211?
30211 is a metric 4T tapered roller bearing to ISO 355: 55 mm bore, 100 mm outside diameter and 22.75 mm assembled width T (2.165 × 3.937 × 0.896 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 103 kN, C0 111 kN (2203E prints no Pu for this size), grease limiting speed 3,600 r/min, oil speed 4,900 r/min, mass about 725 g. It is an open, separable cone/cup bearing with a pressed-steel cage.
What does the 4T prefix mean on 30211?
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 (30211); the lower-case 4t- factory spelling of the code is retained among the search aliases.
How does the 30211 designation encode the 55 mm bore and what is 3DB?
last two digits 11 are the ISO bore code, ×5 = 55 mm (codes 00–03 use the 10/12/15/17 exception table). The 100 mm OD and 22.75 mm assembled T follow the ISO 355 dimension-series plan. 3DB 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 30211 list two speeds, 3,600 and 4,900 r/min?
The lower figure, 3,600 r/min, is the grease-lubricated limiting speed — the mechanical ceiling for the cage, rollers and cone-rib contact. With oil lubrication NTN rates 30211 at 4,900 r/min because oil removes rib-contact heat better. Real limits still depend on preload, oil flow and cooling.
What does the suffix on 30211 mean?
It is the basic open 4T execution — steel cage, adjusted mounting, no seal or feature suffix. NTN uses U for the uprated design, UTG for ULTAGE large-bearing specs, X for the ISO boundary section, and C/CA/D/A for contact-angle or internal-design variants; all are separate order numbers.
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.