N256 bearing: complete specifications & equivalents
The N256 is a ISO 15 radial bearing sized 280 x 500 x 80 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 280 mm |
| Outer diameter D | 500 mm |
| Width B | 80 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 1320 kN |
| Basic static load rating C0 | 1760 kN |
| Fatigue load limit Pu | 143 kN |
| Limiting speed (mechanical) | 1200 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 69400 g |
| Manufacturer designation | NTN N256 |
| 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 & N200-series range
| Bore d | 11.024 in |
|---|---|
| Outer diameter D | 19.685 in |
| Width B | 3.15 in |
| ISO bore code | 56 |
| Radial section height (D−d)/2 | 110 mm |
| Smallest bore in N200-series | 17 mm |
| Largest outer diameter in N200-series | 580 mm |
| Width range across N200-series | 12–92 mm |
| Bore position in N200-series (smallest first) | 33 of 35 |
| Bore above smallest N200-series size | 263 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| N256 | 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 N256 model number is decoded
N256 is an NTN N cylindrical roller bearing: two integral ribs on the inner ring and a ribless separable outer ring — equivalent float behaviour with the separable ring on the housing side, inside the 280×500×80 mm ISO 15 envelope. Reading the code: N for the separable-outer-ring type, then the ISO 15 diameter/width series and the bore code — ×5 = 280 mm (00–03 use the 10/12/15/17 exception table). The 80 mm width and 110.0 mm section put the N200 series in the standard section; wide 22/23 variants at the same bore change OD, width and heat generation and are not drop-in swaps. Speed ratio check: limiting 1,200 r/min is .86 of the 1,400 r/min oil value for N256; grease-churn heating closes that gap as fill quantity rises. After mounting verify the outer ring slides axially by hand at ambient temperature; a stuck float ring in a N256 non-locating position preloads the bearing when the shaft grows.
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
- roller smearing (microwelding) at start-up before the oil film builds under insufficient radial load
- 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
- rolling-contact fatigue after the catalogue L10 life is exceeded
- fretting corrosion on a loose rotating shaft seat
Selection pitfalls — read before you substitute
- At 280 mm bore, oil-lubricated arrangements toward 1,400 r/min need positive flow and drain design; the 69400 g N256 ring stores enough heat that grease-only duty needs a careful relubrication calculation.
- Open N256 units need application-supplied sealing and a defined lubricant schedule; film thickness is the first failure mode for line contact when viscosity drops at the 280 mm contact.
- Minimum radial load is frequently missed in oversized motor and fan selections: an underloaded N256 skids at 1,200 r/min and fails by smearing long before L10 fatigue.
- The N rib arrangement is not interchangeable with another prefix on the same 280 mm seat: inner ring ribbed, outer ring ribless. Swapping NU for NJ changes axial location behaviour even though the 500×80 mm envelope matches.
- Open N256 units need application-supplied sealing and a defined lubricant schedule; film thickness is the first failure mode for line contact when viscosity drops at the 280 mm contact.
- The 1320/1760 kN ratings, 143 kN Pu and 69400 g mass are NTN Ball and Roller Bearings CAT.No.2203E values for N256 (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 N256?
N256 is an NTN N single-row cylindrical roller bearing to ISO 15: 280 mm bore, 500 mm OD and 80 mm width (11.024 × 19.685 × 3.15 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 1320 kN, C0 1760 kN, Pu 143 kN, grease limiting speed 1,200 r/min, oil 1,400 r/min, mass about 69400 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. N256 is two integral ribs on the inner ring and a ribless separable outer ring — equivalent float behaviour with the separable ring on the housing side.
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. N256 is supplied in the standard open execution shown in the table.
Can N256 take axial load and locate a shaft?
the N design is non-locating like NU but floats with the separable outer ring in the housing. 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 N256?
Fw is the inner sub-assembly raceway/roller-set envelope diameter and Ew the outer-ring raceway diameter printed for geometric checks: Fw 340 mm, Ew 440 mm. The nominal bore/OD remain 280/500 mm; Fw/Ew describe the rolling-contact path, and speeds still run to 1,200 r/min grease / 1,400 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.