NU2256 bearing: complete specifications & equivalents
The NU2256 is a ISO 15 radial bearing sized 280 x 500 x 130 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 | 130 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 2050 kN |
| Basic static load rating C0 | 3100 kN |
| Fatigue load limit Pu | 252 kN |
| Limiting speed (mechanical) | 1100 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 107000 g |
| Manufacturer designation | NTN NU2256 |
| 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 & NU2200-series range
| Bore d | 11.024 in |
|---|---|
| Outer diameter D | 19.685 in |
| Width B | 5.118 in |
| ISO bore code | 56 |
| Radial section height (D−d)/2 | 110 mm |
| Smallest bore in NU2200-series | 17 mm |
| Largest outer diameter in NU2200-series | 1030 mm |
| Width range across NU2200-series | 16–272 mm |
| Bore position in NU2200-series (smallest first) | 32 of 39 |
| Bore above smallest NU2200-series size | 263 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| NU2256-ECML | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 280×500×130 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 NU2256 model number is decoded
NTN lists NU2256 on the 280×500 mm envelope, 130 mm wide: a line-contact radial bearing with a pressed sheet-steel cage and a grease limiting speed of 1,100 r/min. On the NTN nameplate NU states which ring carries the ribs, which determines whether NU2256 floats or locates; the numeric remainder is the ISO 15 series and 280 mm bore reference, not a fit or clearance instruction. At 1,300 r/min with oil versus 1,100 r/min with grease (a 200 r/min band), lubrication choice for NU2256 is a thermal decision, not just a sealing one. Selection arithmetic: Pu 252 kN is the fatigue load limit feeding the adjusted-life equation, and the C0/C ratio of 1.51 (3100/2050 kN) shows the high-static-capacity proportioning of this 280 mm bore. Heat the inner ring to max 120 °C for the 280 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
- ship propulsion line shafts and reduction gears
- mining SAG/ball-mill drive shafts
- offshore drawworks and winch drums
- heavy press and large gearbox main shafts
Known failure patterns
- inner-ring raceway spalling from overload in the line-contact Hertzian zone
- cage distortion after a mounting blow carried through the roller set
- grease starvation and cage drag when relubrication intervals are extended past the grease life
- electrical pitting on VFD-driven motor shafts without grounding protection
- brinelling from static overload or impact during handling
Selection pitfalls — read before you substitute
- At 280 mm bore, oil-lubricated arrangements toward 1,300 r/min need positive flow and drain design; the 107000 g NU2256 ring stores enough heat that grease-only duty needs a careful relubrication calculation.
- The EA high-capacity roller complement changes the load figure versus the basic execution of the same number; the 2050/3100 kN pair here belongs to NU2256 as printed, not to the bare size.
- If the shaft must be located both ways, do not use NU2256 alone: pair it with a locating bearing or specify the NUP execution with the matching loose rib ring from the 2203E table.
- The NU rib arrangement is not interchangeable with another prefix on the same 280 mm seat: outer ring ribbed, inner ring ribless. Swapping NU for NJ changes axial location behaviour even though the 500×130 mm envelope matches.
- Grease limiting speed 1,100 r/min and oil 1,300 r/min are different limits for NU2256: the first is the cage/lubricant mechanical ceiling, the second assumes real oil flow rather than an oil bath.
- The 2050/3100 kN ratings, 252 kN Pu and 107000 g mass are NTN Ball and Roller Bearings CAT.No.2203E values for NU2256 (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 NU2256?
NU2256 is an NTN NU single-row cylindrical roller bearing to ISO 15: 280 mm bore, 500 mm OD and 130 mm width (11.024 × 19.685 × 5.118 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 2050 kN, C0 3100 kN, Pu 252 kN, grease limiting speed 1,100 r/min, oil 1,300 r/min, mass about 107000 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. NU2256 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. NU2256 is supplied in the standard open execution shown in the table.
Can NU2256 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 NU2256?
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 1,100 r/min grease / 1,300 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.