29256-NTN bearing: complete specifications & equivalents
The 29256-NTN is a ISO 104 radial bearing sized 280 x 380 x 60 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 | 380 mm |
| Width B | 60 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | brass |
| Basic dynamic load rating C | 975 kN |
| Basic static load rating C0 | 4050 kN |
| Fatigue load limit Pu | 245 kN |
| Limiting speed (mechanical) | 1000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 19800 g |
| Manufacturer designation | NTN 29256 |
| Standard | ISO 104 |
| 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 & 29200-series range
| Bore d | 11.024 in |
|---|---|
| Outer diameter D | 14.961 in |
| Width B | 2.362 in |
| ISO bore code | 56 |
| Radial section height (D−d)/2 | 50 mm |
| Smallest bore in 29200-series | 150 mm |
| Largest outer diameter in 29200-series | 1060 mm |
| Width range across 29200-series | 39–155 mm |
| Bore position in 29200-series (smallest first) | 10 of 26 |
| Bore above smallest 29200-series size | 130 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 29256 | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 280×380×60 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 29256-NTN model number is decoded
NTN 29256 belongs to the light-section 29200 spherical-thrust family of spherical roller thrust bearings: 280 / 380 / 60 mm (bore / OD / height). Reading the code: 292 is the dimension series (light-section 29200 spherical-thrust family), and 56 encodes the 280 mm bore (bore code x 5). Catalogue mass is about 20 kg for the full washer-and-roller stack. If speed climbs toward the 1,000 r/min oil rating, the lubrication design — bath, circulation, cooling — becomes the real selection criterion. Check face runout of the support surfaces before assembly: the self-aligning feature absorbs steady misalignment, not a rocking seat.
Typical equipment & failure modes
Common applications
- heavy stacker/reclaimer and shiploading pivots
- vertical hydro and pump-turbine main thrust blocks
- heavy rolling-mill and forging-press thrust seats
- large marine propulsion thrust supports
Known failure patterns
- cage and roller-end scoring when the shaft was forced into alignment by the bearing itself during a bent-shaft rescue
- roller/raceway scuffing from an interrupted oil supply — at these loads the EHL film is the only thing between rolling and smearing
- flaking that started where radial load share grew past the design assumption — the bearing tolerates combined load only while axial load clearly dominates
- thermal distress when oil viscosity was chosen by habit instead of the operating-temperature calculation
- fretting on the shaft seat after the washer crept under reversing axial shock
Selection pitfalls — read before you substitute
- At 280 mm bore, seating geometry, oil supply and the minimum-load guarantee decide life — field improvisation on any of the three is the usual root cause.
- The 292 light section is the speed-and-space end of the spherical-thrust plan — for the same 280 mm bore it trades capacity for a smaller 380 mm OD and lower height.
- Self-aligning does not mean self-locating: the housing washer must stay free on its spherical seat — clamping it flat destroys the feature the 29256 was chosen for.
- Below the minimum axial load the rollers skid; at 1,000 r/min the Ca of 975 kN never comes into play before the raceway is smeared.
- The 60 mm stack height is part of the load path — any spacer or shim stack added under the housing washer must carry the full thrust without settling.
- The Ca 975/C0a 4050 kN ratings and 245 kN Pu here are NTN Ball and Roller Bearings CAT.No.2203E figures for 29256; roller profile and osculation legitimately differ between manufacturers, so re-verify ratings, oil supply and minimum load before substituting another make.
Frequently asked questions
What are the dimensions and catalogue ratings of NTN 29256?
29256 is a spherical roller thrust bearing to ISO 104: 280 mm shaft-washer bore, 380 mm outside diameter, 60 mm stack height (11.024 x 14.961 x 2.362 in). From NTN Ball and Roller Bearings CAT.No.2203E: axial Ca 975 kN, C0a 4050 kN and a 245 kN fatigue load limit Pu; limiting speed 1,000 r/min with oil lubrication; mass about 19800 g.
How is the 29256 designation structured?
292 is the dimension series (light-section 29200 spherical-thrust family); 56 encodes the 280 mm bore (bore code x 5). The 380 mm OD and 60 mm height follow the ISO 104 boundary plan for that series.
Can 29256 handle misalignment and radial load?
Yes to both, with limits. The spherical housing-washer raceway lets the bearing self-align against steady seat misalignment, and the angled roller contact tolerates a radial share while axial load clearly dominates. It is not a radial bearing: shaft radial location still needs its own radial bearing.
Why does NTN print only an oil speed, 1,000 r/min, for 29256?
Spherical roller thrust bearings of this size work under contact stresses that need an elastohydrodynamic oil film; grease is reserved for the smallest, slowest duties. The printed figure is the limiting speed with the catalogue oil-lubrication state — bath level, viscosity and cooling decide how close a real installation may run.
What should be checked before substituting another make for 29256?
The 280/380/60 mm envelope is ISO 104 interchangeable, but roller profile, osculation, cage and washer details are maker-specific. Re-verify Ca 975 kN / C0a 4050 kN, the oil speed rating and the minimum-load requirement against the donor catalogue before swapping on a rated drive.
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.