32230U bearing: complete specifications & equivalents
The 32230U is a ISO 355 radial bearing sized 150 x 270 x 77 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 150 mm |
| Outer diameter D | 270 mm |
| Width B | 77 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 775 kN |
| Basic static load rating C0 | 1070 kN |
| Fatigue load limit Pu | 105 kN |
| Limiting speed (mechanical) | 1300 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 18000 g |
| Manufacturer designation | NTN 32230U |
| 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 & 32200-series range
| Bore d | 5.906 in |
|---|---|
| Outer diameter D | 10.63 in |
| Width B | 3.031 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 60 mm |
| Smallest bore in 32200-series | 17 mm |
| Largest outer diameter in 32200-series | 580 mm |
| Width range across 32200-series | 17.25–159 mm |
| Bore position in 32200-series (smallest first) | 25 of 36 |
| Bore above smallest 32200-series size | 133 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 32230U | 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 32230U model number is decoded
32230U is the NTN 4T catalogue entry for a 150×270×77 mm metric tapered roller bearing — separable cone and cup, designed for combined radial and axial load as an individually adjusted bearing. NTN also quotes this bearing with its ISO 355 dimension-series abbreviation, 4GD, which is the maker-neutral cross-reference for the 150×270 mm envelope; 4T is NTN's own tapered-roller brand mark on the parts. A tapered roller bearing reacts combined radial and one-direction axial load; NTN mounts 32230U cone and cup separately and adjusts end play or preload against a second bearing, so the arrangement locates the shaft in both directions. The two speed columns differ by a factor of .76 (grease/limiting 1,300 vs oil 1,700 r/min); heat generation at the cone rib decides which lubrication a real 32230U arrangement can sustain. With a rotating shaft a m6/n6 shaft seat and a press-fit cup are typical catalogue practice for 32230U; reverse the logic if the cup rotates, and re-verify against load direction and magnitude.
Typical equipment & failure modes
Common applications
- cement-plant kiln and mill drive trains
- rolling-mill roll-neck and gearbox positions
- large crusher and SAG/AG-mill drive shafts
- wind-turbine gearbox and main-shaft arrangements
Known failure patterns
- cone-raceway spalling at the large rib when preload is set too high for the lubricant film
- preload loss from racewear when one bearing of the paired set is replaced without re-adjusting end play
- rib scoring when axial load is carried beyond the cone rib capacity of the adjusted pair
- cage fatigue when the pair is run continuously near the grease limiting speed without oil cooling
- water-induced pitting when the open bearing is exposed to washdown without external seals
Selection pitfalls — read before you substitute
- At 150 mm bore the 32230U set is adjusted with hydraulic nuts on large mill and wind positions; follow the drive-up angle/end-play procedure, because manual torque methods cannot control preload at the 775 kN C level.
- The heavy-section 32200 family at 150 mm bore (270×77 mm assembled) carries more capacity than the lighter 320/329 sections but generates more preload heat; confirm oil availability before running near the 1,700 r/min oil ceiling.
- The 60.0 mm section leaves little room for an oversized shaft fillet; check the mounting-chamfer table for 32230U or the ring will bottom out on the radius instead of the shoulder face.
- Back-to-back and face-to-face arrangements react differently to shaft bending: pick the pair orientation for the moment load before locking the 150 mm shoulder geometry, because retrofitting flips the cups.
- Do not confuse T (77 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.
- The 775/1070 kN ratings and 105 kN Pu here are NTN Ball and Roller Bearings CAT.No.2203E figures for 32230U (ISO 355 4GD); 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 32230U?
32230U is a metric 4T tapered roller bearing to ISO 355: 150 mm bore, 270 mm outside diameter and 77 mm assembled width T (5.906 × 10.63 × 3.031 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 775 kN, C0 1070 kN, Pu 105 kN, grease limiting speed 1,300 r/min, oil speed 1,700 r/min, mass about 18000 g. It is an open, separable cone/cup bearing with a pressed-steel cage.
What does the 4T prefix mean on 32230U?
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 (32230U); the lower-case 4t- factory spelling of the code is retained among the search aliases.
How does the 32230U designation encode the 150 mm bore and what is 4GD?
last two digits 30 are the ISO bore code, ×5 = 150 mm (codes 00–03 use the 10/12/15/17 exception table). The 270 mm OD and 77 mm assembled T follow the ISO 355 dimension-series plan. 4GD 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 32230U list two speeds, 1,300 and 1,700 r/min?
The lower figure, 1,300 r/min, is the grease-lubricated limiting speed — the mechanical ceiling for the cage, rollers and cone-rib contact. With oil lubrication NTN rates 32230U at 1,700 r/min because oil removes rib-contact heat better. Real limits still depend on preload, oil flow and cooling.
What does the suffix on 32230U mean?
Suffix reading on 32230U: 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.