NN3056 bearing: complete specifications & equivalents
The NN3056 is a ISO 15 radial bearing sized 280 x 420 x 106 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 | 420 mm |
| Width B | 106 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 1200 kN |
| Basic static load rating C0 | 2080 kN |
| Fatigue load limit Pu | 174 kN |
| Limiting speed (mechanical) | 1300 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 51100 g |
| Manufacturer designation | NTN NN3056 |
| 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 & NN3000-series range
| Bore d | 11.024 in |
|---|---|
| Outer diameter D | 16.535 in |
| Width B | 4.173 in |
| ISO bore code | 56 |
| Radial section height (D−d)/2 | 70 mm |
| Smallest bore in NN3000-series | 25 mm |
| Largest outer diameter in NN3000-series | 680 mm |
| Width range across NN3000-series | 16–163 mm |
| Bore position in NN3000-series (smallest first) | 31 of 40 |
| Bore above smallest NN3000-series size | 255 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| NN3056 | 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 NN3056 model number is decoded
NN3056 is an NTN NN cylindrical roller bearing: two integral ribs on the outer ring and a ribless, separable inner ring — a non-locating bearing that lets the shaft float axially, inside the 280×420×106 mm ISO 15 envelope. Numbering ties NN3056 to its envelope: type code NN, series NN3000, 280 mm bore; the 420×106 mm outline therefore swaps dimensionally with other ISO 15 bearings of the same code, though rib arrangements differ by prefix. Minimum radial load matters: an unloaded NN3056 at high speed skids its rollers and smears the raceway; spring preload or the rotor weight typically covers the requirement in motors and pumps. With the inner ring rotating, catalogue practice is a m6/n6 shaft seat and an H7/H6 housing; the outer ring must remain free to creep slightly axially in non-locating NN arrangements. Housing and shaft fillets must clear the ring chamfers of NN3056; an oversized radius locks the ring on its face and tilts the 106 mm-wide seat.
Typical equipment & failure modes
Common applications
- coordinate-measuring and semiconductor-equipment drives
- machine-tool main spindles requiring high radial stiffness
- precision gearbox and indexing-drive shafts
- high-rpm motorised grinding and milling spindles
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
- grease starvation and cage drag when relubrication intervals are extended past the grease life
- edge loading from shaft deflection beyond the 3–4 arc-minute alignment limit
- brinelling from static overload or impact during handling
Selection pitfalls — read before you substitute
- At 280 mm bore, oil-lubricated arrangements toward 1,600 r/min need positive flow and drain design; the 51100 g NN3056 ring stores enough heat that grease-only duty needs a careful relubrication calculation.
- Never press either ring through the roller complement when fitting: mounting force goes through the ring faces, or the 420 mm race brinells and releases as vibration within hours.
- Never press either ring through the roller complement when fitting: mounting force goes through the ring faces, or the 420 mm race brinells and releases as vibration within hours.
- Open NN3056 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.
- Do not replace NN3056 with a deep-groove ball bearing on rating alone: line contact gives 1200 kN radial capacity but the bearing cannot carry the thrust duty a ball bearing can and misalignment tolerance is only 3–4 arc-minutes.
- The 1200/2080 kN ratings, 174 kN Pu and 51100 g mass are NTN Ball and Roller Bearings CAT.No.2203E values for NN3056 (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 NN3056?
NN3056 is an NTN NN double-row precision cylindrical roller bearing to ISO 15: 280 mm bore, 420 mm OD and 106 mm width (11.024 × 16.535 × 4.173 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 1200 kN, C0 2080 kN, Pu 174 kN, grease limiting speed 1,300 r/min, oil 1,600 r/min, mass about 51100 g. It is open, with a machined or stamped steel cage per the precision execution.
What is the difference between NU, NJ, NUP, N and NF cylindrical roller bearings?
NN and NNU are double-row precision designs rather than single-row rib variants: NN has a ribbed inner ring and separable outer ring, NNU the reverse; both give high radial stiffness for spindles and are commonly ordered with P5/P4 precision and a K 1:12 tapered bore for preload setting. NN3056 is the NN execution.
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. NN3056 is supplied in the standard open execution shown in the table.
What does the K tapered bore mean on a precision NN bearing like NN3056?
NN3056 has a cylindrical bore and mounts on a plain machined shaft seat; a K execution (1:12 taper) exists in the NN3000 series when preload must be set by drive-up on a tapered seat.
What speeds and lubrication apply to NN3056?
NTN rates NN3056 at 1,300 r/min with grease and 1,600 r/min with oil. The grease figure is the cage/film mechanical ceiling; the oil figure assumes circulating or carefully supplied oil that removes heat from the line-contact zone.
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.