30320U bearing: complete specifications & equivalents
The 30320U is a ISO 355 radial bearing sized 100 x 215 x 51.5 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 100 mm |
| Outer diameter D | 215 mm |
| Width B | 51.5 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 455 kN |
| Basic static load rating C0 | 500 kN |
| Fatigue load limit Pu | 53 kN |
| Limiting speed (mechanical) | 1800 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 8300 g |
| Manufacturer designation | NTN 30320U |
| 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 & 30300-series range
| Bore d | 3.937 in |
|---|---|
| Outer diameter D | 8.465 in |
| Width B | 2.028 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 57.5 mm |
| Smallest bore in 30300-series | 15 mm |
| Largest outer diameter in 30300-series | 500 mm |
| Width range across 30300-series | 14.25–105 mm |
| Bore position in 30300-series (smallest first) | 19 of 32 |
| Bore above smallest 30300-series size | 85 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 30320U | ISO 15 | full Dimensions and internal design equivalent — standard interchange. | ISO 15 boundary-dimension envelope; brand-specific OEM equivalents (NSK/FAG/NTN) pending multi-source data. |
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 30320U model number is decoded
30320U belongs to the NTN metric 4T tapered roller range (large-OD 30300 family with the steeper contact angle); the open bearing leaves sealing to the application and is normally ordered and mounted as an adjustable matched pair. NTN also quotes this bearing with its ISO 355 dimension-series abbreviation, 2GB, which is the maker-neutral cross-reference for the 100×215 mm envelope; 4T is NTN's own tapered-roller brand mark on the parts. Suffix reading on 30320U: 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. Selection: C 455 kN against C0 500 kN gives a C0/C ratio of 1.10 for the 100 mm bore, and the equivalent combined load must keep below the rating at the target L10 with the pair counted as one unit. Open 4T bearings need application seals; without them the grease at the cone rib of 30320U washes out and the rib/roller-end contact smears on the first wet or dusty shift.
Typical equipment & failure modes
Common applications
- mineral-processing feeder and crusher auxiliaries
- marine winch and deck-machinery shafts
- paper-machine press-section rolls
- large agricultural and forestry machine axles
Known failure patterns
- cone-raceway spalling at the large rib when preload is set too high for the lubricant film
- rib scoring when axial load is carried beyond the cone rib capacity of the adjusted pair
- preload loss from racewear when one bearing of the paired set is replaced without re-adjusting end play
- pressed-steel cage pocket wear from roller skid at light radial load and high speed
- fretting corrosion on a loose cone seat that creeps under rotating load
Selection pitfalls — read before you substitute
- Mount the 100 mm cone by induction heating (max 120 °C) and the cup with a press sleeve; the 8300 g ring mass makes cocking during fitting a direct raceway-brinelling risk.
- The steeper contact angle of the large-OD 30300 family with the steeper contact angle raises axial capacity but lowers the speed ceiling against a 302/322 bearing at 100 mm bore; do not swap to the lighter family without re-checking the 1,800 r/min grease limit and the thrust load split.
- The U/UTG/X/C/CA/D suffix variants of a base number share the bore but not the article: ordering 30320U by size alone can deliver the wrong contact-angle execution for a pinion position.
- Minimum load matters at high speed: an unloaded 30320U at a large fraction of 1,800 r/min lets rollers skid and smear the cone rib; spring-preload lightly loaded pair arrangements.
- ISO 355 makes the 100×215 mm envelope interchangeable but not the ratings: NTN prints 455/500 kN for this execution, and a cheaper same-number part can differ in roller complement and steel.
- The 455/500 kN ratings and 53 kN Pu here are NTN Ball and Roller Bearings CAT.No.2203E figures for 30320U (ISO 355 2GB); 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 30320U?
30320U is a metric 4T tapered roller bearing to ISO 355: 100 mm bore, 215 mm outside diameter and 51.5 mm assembled width T (3.937 × 8.465 × 2.028 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 455 kN, C0 500 kN, Pu 53 kN, grease limiting speed 1,800 r/min, oil speed 2,400 r/min, mass about 8300 g. It is an open, separable cone/cup bearing with a pressed-steel cage.
What does the 4T prefix mean on 30320U?
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 (30320U); the lower-case 4t- factory spelling of the code is retained among the search aliases.
How does the 30320U designation encode the 100 mm bore and what is 2GB?
last two digits 20 are the ISO bore code, ×5 = 100 mm (codes 00–03 use the 10/12/15/17 exception table). The 215 mm OD and 51.5 mm assembled T follow the ISO 355 dimension-series plan. 2GB 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 30320U list two speeds, 1,800 and 2,400 r/min?
The lower figure, 1,800 r/min, is the grease-lubricated limiting speed — the mechanical ceiling for the cage, rollers and cone-rib contact. With oil lubrication NTN rates 30320U at 2,400 r/min because oil removes rib-contact heat better. Real limits still depend on preload, oil flow and cooling.
What does the suffix on 30320U mean?
Suffix reading on 30320U: 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.