NU228 bearing: complete specifications & equivalents
The NU228 is a ISO 15 radial bearing sized 140 x 250 x 42 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 | 42 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 345 kN |
| Basic static load rating C0 | 400 kN |
| Fatigue load limit Pu | 39.5 kN |
| Limiting speed (mechanical) | 2700 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 7720 g |
| Manufacturer designation | NTN NU228 |
| Standard | ISO 15 |
| 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 & NU200-series range
| Bore d | 5.512 in |
|---|---|
| Outer diameter D | 9.843 in |
| Width B | 1.654 in |
| ISO bore code | 28 |
| Radial section height (D−d)/2 | 55 mm |
| Smallest bore in NU200-series | 15 mm |
| Largest outer diameter in NU200-series | 580 mm |
| Width range across NU200-series | 11–92 mm |
| Bore position in NU200-series (smallest first) | 24 of 36 |
| Bore above smallest NU200-series size | 125 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| NU228-ECM | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 140×250×42 mm envelope per ISO 15; catalogue load ratings differ by >10% — re-rate the application before substituting. |
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 NU228 model number is decoded
In NTN Ball and Roller Bearings CAT.No.2203E, NU228 appears as a 140 mm bore single-row cylindrical roller bearing (345 kN C / 400 kN C0) with a pressed sheet-steel cage, listed to the ISO 15 boundary plan. On the NTN nameplate NU states which ring carries the ribs, which determines whether NU228 floats or locates; the numeric remainder is the ISO 15 series and 140 mm bore reference, not a fit or clearance instruction. Line contact between rollers and raceways gives NU228 high radial capacity but no tolerance for misalignment: beyond roughly 3–4 arc-minutes the roller ends edge-load and fatigue accelerates. Equivalent-load planning treats NU228 as a pure radial bearing: keep P below 345 kN at the required L10, and let a paired angular-contact or thrust part carry any sustained axial component. Heat the inner ring to max 120 °C for the 140 mm interference fit and support the ring face square during fitting; cocking over a keyway brinells the raceway before first rotation.
Typical equipment & failure modes
Common applications
- heavy press and large gearbox main shafts
- rolling-mill work-roll and backup-roll positions
- large turbine and generator rotor bearings
- wind-turbine gearbox planet and rotor shafts
Known failure patterns
- inner-ring raceway spalling from overload in the line-contact Hertzian zone
- pressed-steel cage pocket wear when rollers skid at light load or too-thin lubricant
- micro-pitting when the EHL film falls below the composite roughness at high specific load
- false brinelling on standby machines exposed to external vibration
- hard-particle indentation of raceways in unfiltered oil or open arrangements
Selection pitfalls — read before you substitute
- At 140 mm bore, oil-lubricated arrangements toward 3,100 r/min need positive flow and drain design; the 7720 g NU228 ring stores enough heat that grease-only duty needs a careful relubrication calculation.
- The NU rib arrangement is not interchangeable with another prefix on the same 140 mm seat: outer ring ribbed, inner ring ribless. Swapping NU for NJ changes axial location behaviour even though the 250×42 mm envelope matches.
- Never press either ring through the roller complement when fitting: mounting force goes through the ring faces, or the 250 mm race brinells and releases as vibration within hours.
- Grease limiting speed 2,700 r/min and oil 3,100 r/min are different limits for NU228: the first is the cage/lubricant mechanical ceiling, the second assumes real oil flow rather than an oil bath.
- Wide (22/23) and light (10/49) executions at 140 mm bore share bore but not OD/width; check the full NU200 series code before substituting, because housing and shoulder geometry will not interchange.
- The 345/400 kN ratings, 39.5 kN Pu and 7720 g mass are NTN Ball and Roller Bearings CAT.No.2203E values for NU228 (standard execution); other makes sharing the ISO 15 envelope revise internal geometry without changing the order number, so keep the 2203E reference with the specification for critical drives.
Frequently asked questions
What are the dimensions and catalogue data of NU228?
NU228 is an NTN NU single-row cylindrical roller bearing to ISO 15: 140 mm bore, 250 mm OD and 42 mm width (5.512 × 9.843 × 1.654 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 345 kN, C0 400 kN, Pu 39.5 kN, grease limiting speed 2,700 r/min, oil 3,100 r/min, mass about 7720 g. It is open, with a pressed sheet-steel cage.
What is the difference between NU, NJ, NUP, N and NF cylindrical roller bearings?
The prefix states the rib arrangement: NU has two outer-ring ribs and a ribless inner ring (float, no axial load); NJ adds ribs for one-direction location; NUP adds a loose L-ring to locate both directions; N has two inner-ring ribs and a separable outer ring; NF has one rib per ring for one-direction guidance. NU228 is two integral ribs on the outer ring and a ribless, separable inner ring — a non-locating bearing that lets the shaft float axially.
What do the EA, E and ＊ suffixes mean on NTN cylindrical roller bearings?
EA is NTN's high-capacity design with a pressed sheet-steel cage and optimised roller complement in the same ISO 15 envelope; E marks the high-capacity design at the larger bores; the ＊ symbol printed before the code in the NTN catalogue marks the ULTAGE new-generation specification and is not typed as part of the order number. NU228 is supplied in the standard open execution shown in the table.
Can NU228 take axial load and locate a shaft?
the NU design carries no axial load and floats axially on both sides. Provide axial location with an adjacent locating bearing (angular-contact, deep-groove or a paired NJ/NUP set).
What do Fw and Ew mean for NU228?
Fw is the inner sub-assembly raceway/roller-set envelope diameter and Ew the outer-ring raceway diameter printed for geometric checks: Fw 169 mm, Ew 221 mm. The nominal bore/OD remain 140/250 mm; Fw/Ew describe the rolling-contact path, and speeds still run to 2,700 r/min grease / 3,100 r/min oil.
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.