32228U bearing: complete specifications & equivalents
The 32228U is a ISO 355 radial bearing sized 140 x 250 x 71.75 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 140 mm |
| Outer diameter D | 250 mm |
| Width B | 71.75 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 675 kN |
| Basic static load rating C0 | 920 kN |
| Fatigue load limit Pu | 92 kN |
| Limiting speed (mechanical) | 1400 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 14200 g |
| Manufacturer designation | NTN 32228U |
| 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 | 5.512 in |
|---|---|
| Outer diameter D | 9.843 in |
| Width B | 2.825 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 55 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) | 24 of 36 |
| Bore above smallest 32200-series size | 123 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 32228U | 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 32228U model number is decoded
The NTN 2203E table prints 32228U in the heavy-section 32200 family: 140 mm bore, 250 mm cup OD, 71.75 mm T, with a grease limiting speed of 1,400 r/min and an oil-lubricated ceiling of 1,900 r/min. Reading the designation: the leading five digits follow the ISO 355 metric plan (dimension family plus two-digit bore code), and 32228U resolves to 140 mm bore; the NTN factory mark 4T is stamped on cone and cup but is a brand mark, not a size code, so the catalogue sku is printed without it. The pressed-steel cage and surface-finished roller ends are standard 4T execution; ULTAGE-marked variants use upgraded material and internal geometry aimed at longer rating life with the same ISO 355 envelope. The 55.0 mm section height over the 140 mm bore positions the load centre; axial location of the pair depends on that contact line, so spacer faces must be square within the P0 tolerance of the bearing. Fillet radii must clear the ring chamfers of the 250 mm cup and 140 mm cone; use undercut shoulders so the rings seat fully rather than bridging on a shaft radius.
Typical equipment & failure modes
Common applications
- wind-turbine gearbox and main-shaft arrangements
- offshore crane and drawworks drums
- heavy haul railway traction gearboxes
- large marine propulsion reduction gears
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 fatigue when the pair is run continuously near the grease limiting speed without oil cooling
- brinell marks on cone and cup raceways from impact during handling or hammering during fitting
Selection pitfalls — read before you substitute
- At 140 mm bore the 32228U 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 675 kN C level.
- The heavy-section 32200 family at 140 mm bore (250×71.75 mm assembled) carries more capacity than the lighter 320/329 sections but generates more preload heat; confirm oil availability before running near the 1,900 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 140 mm shoulder geometry, because retrofitting flips the cups.
- The 55.0 mm section leaves little room for an oversized shaft fillet; check the mounting-chamfer table for 32228U or the ring will bottom out on the radius instead of the shoulder face.
- Replacing one half of an adjusted pair without resetting end play negates the 71.75 mm T dimension logic: re-adjust the set and re-verify the contact pattern rather than reusing the old spacer stack.
- The 675/920 kN ratings and 92 kN Pu here are NTN Ball and Roller Bearings CAT.No.2203E figures for 32228U (ISO 355 4FD); 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 32228U?
32228U is a metric 4T tapered roller bearing to ISO 355: 140 mm bore, 250 mm outside diameter and 71.75 mm assembled width T (5.512 × 9.843 × 2.825 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 675 kN, C0 920 kN, Pu 92 kN, grease limiting speed 1,400 r/min, oil speed 1,900 r/min, mass about 14200 g. It is an open, separable cone/cup bearing with a pressed-steel cage.
What does the 4T prefix mean on 32228U?
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 (32228U); the lower-case 4t- factory spelling of the code is retained among the search aliases.
How does the 32228U designation encode the 140 mm bore and what is 4FD?
last two digits 28 are the ISO bore code, ×5 = 140 mm (codes 00–03 use the 10/12/15/17 exception table). The 250 mm OD and 71.75 mm assembled T follow the ISO 355 dimension-series plan. 4FD 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 32228U list two speeds, 1,400 and 1,900 r/min?
The lower figure, 1,400 r/min, is the grease-lubricated limiting speed — the mechanical ceiling for the cage, rollers and cone-rib contact. With oil lubrication NTN rates 32228U at 1,900 r/min because oil removes rib-contact heat better. Real limits still depend on preload, oil flow and cooling.
What does the suffix on 32228U mean?
Suffix reading on 32228U: 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.