NJ256 bearing: complete specifications & equivalents
The NJ256 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 NJ256 |
| 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 & NJ200-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 NJ200-series | 15 mm |
| Largest outer diameter in NJ200-series | 580 mm |
| Width range across NJ200-series | 11–92 mm |
| Bore position in NJ200-series (smallest first) | 34 of 36 |
| Bore above smallest NJ200-series size | 265 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| NJ256-MA | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 280×500×80 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 NJ256 model number is decoded
NTN lists NJ256 on the 280×500 mm envelope, 80 mm wide: a line-contact radial bearing with a pressed sheet-steel cage and a grease limiting speed of 1,200 r/min. Numbering ties NJ256 to its envelope: type code NJ, series NJ200, 280 mm bore; the 500×80 mm outline therefore swaps dimensionally with other ISO 15 bearings of the same code, though rib arrangements differ by prefix. The 80 mm width and 110.0 mm section put the NJ200 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 NJ256; grease-churn heating closes that gap as fill quantity rises. On NJ arrangements confirm which ring is separable before heating: forcing the ribbed ring off over the roller complement damages the cage and rib faces.
Typical equipment & failure modes
Common applications
- offshore drawworks and winch drums
- heavy press and large gearbox main shafts
- rolling-mill work-roll and backup-roll positions
- large turbine and generator rotor bearings
Known failure patterns
- inner-ring raceway spalling from overload in the line-contact Hertzian zone
- cage wear accelerated when the EA high-capacity roller complement runs continuously above its thermal balance
- micro-pitting when the EHL film falls below the composite roughness at high specific load
- fretting corrosion on a loose rotating shaft seat
- rolling-contact fatigue after the catalogue L10 life is exceeded
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 NJ256 ring stores enough heat that grease-only duty needs a careful relubrication calculation.
- If the shaft must be located both ways, do not use NJ256 alone: pair it with a locating bearing or specify the NUP execution with the matching loose rib ring from the 2203E table.
- The 80 mm width and abutment faces must be square to the axis; a tilted spacer concentrates load across the roller set and shows as uneven raceway polish on the 280 mm inner ring.
- Open NJ256 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.
- Open NJ256 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 NJ256 (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 NJ256?
NJ256 is an NTN NJ 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. NJ256 is two integral ribs on the inner ring and one rib on the outer ring — it locates the shaft in one axial direction.
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. NJ256 is supplied in the standard open execution shown in the table.
Can NJ256 take axial load and locate a shaft?
the NJ design accepts axial load in one direction and provides one-way shaft location. For two-direction location use an NUP execution or an NJ pair with loose rib rings.
What do Fw and Ew mean for NJ256?
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.