29256 bearing: complete specifications & equivalents
The 29256 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 | SKF |
| 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 | steel |
| Basic dynamic load rating C | 863 kN |
| Basic static load rating C0 | 4000 kN |
| Fatigue load limit Pu | 375 kN |
| Reference speed (thermal) | 1000 rpm |
| Limiting speed (mechanical) | 1700 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 19500 g |
| Manufacturer designation | 29256 |
| Standard | ISO 104 |
| Catalog version | SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 13.1 spherical roller thrust bearings |
| Last verified | 2026-09-27 |
Source: catalog reference (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 13.1 spherical roller thrust bearings) · extracted 2026-09-27
Parameters extracted from the official SKF Rolling Bearings catalogue (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 13.1 spherical roller thrust bearings); SKF® and SKF Explorer® are trademarks of AB SKF, used here for identification only — mpnbase is not an authorized SKF distributor. Boundary dimensions are ISO 15 interchangeable; current production values may differ, verify at skf.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) | 7 of 23 |
| Bore above smallest 29200-series size | 130 mm |
Cross references & equivalents
No verified interchange data yet. Send an inquiry and our team will confirm equivalents manually.
How the 29256 model number is decoded
Where a cylindrical roller thrust bearing would edge-load under deflection, 29256 aligns itself: 280×380×60 mm envelope, 4000 kN static rating, one load direction. SKF suffixes on spherical roller thrust bearings describe cages: E the standard stamped steel window cage, EM the machined brass execution, EF the extra-large steel-cage design; 29256 is the steel cage of the earlier standard design. The contact geometry also accepts simultaneous radial load up to roughly 55 % of the simultaneous axial force; beyond that mix, add a separate radial bearing to the arrangement. Static safety matters for shock duty: compare peak axial force against C0 4000 kN with the application's static factor, since crane hooks and screw positions see their worst load at zero or low speed. Mounting: fit the shaft washer tight on the 280 mm seat, seat the sphered housing washer on its matching (often separately supplied) seating washer, and check the assembly swivels freely before applying the 863 kN working load.
Typical equipment & failure modes
Common applications
- marine shaft and rudder-style thrust positions with seat deflection
- paper machine calender and refiner discs with combined axial and radial force
- crane hook assemblies where the hook block turns under full load
- injection moulding machine and extruder screw thrust positions
Known failure patterns
- cage wear from rollers being dragged through unloaded zones under fluctuating thrust
- washer back-face fretting where the seat is too narrow to support the full ring face
- grease churning and overheating when a high-speed thrust position is over-packed
- hard-particle indentation where oil or grease filtration is inadequate
- roller skidding and raceway glazing once the thrust falls below the catalogue minimum axial load (factor A)
Selection pitfalls — read before you substitute
- At 280 mm bore, oil flow becomes the design variable: the 863 kN rating assumes fresh oil at the contact, and a blocked feed groove halves real life.
- The 863/4000 kN figures assume the matching sphered seating washer is fitted where the catalogue calls for it; a flat housing seat removes the self-aligning function.
- Minimum load factor A 1.5 dominates commissioning: start the oil flow and preload before rotation, especially on 292 bearings where an unloaded cold start smears the rollers.
- the 1,000 r/min reference speed is the thermal criterion under load, the 1,700 r/min limiting speed is the mechanical ceiling; large 292 bearings are normally run well below it with oil cooling.
- Radial force beyond the permitted fraction of simultaneous thrust (about 0.55·F_a) overloads one side of the barrel-roller set — add a radial bearing instead of leaning on 29256.
- The 863/4000 kN ratings and 19500 g mass are SKF catalogue values transcribed from ch. 13.1 of PUB BU/P1 17000 (PDF table page 926); mounting data — the minimum axial load factor A — appears in the running text because the structured record carries the boundary envelope only.
Frequently asked questions
What destroys a spherical roller thrust bearing?
Unloaded rotation below A 1.5 (roller smearing), interrupted oil supply on the large sizes, a missing sphered seating washer that removes alignment, and contamination. Limiting speed here is 1,700 r/min.
Which dimensions does the 29256 have?
A 29256 measures 280 mm bore × 380 mm outside diameter × 60 mm width (11.024 × 14.961 × 2.362 in). From SKF catalogue PUB BU/P1 17000: dynamic C 863 kN, static C0 4000 kN, fatigue limit Pu 375 kN, reference speed 1,000 r/min, limiting speed 1,700 r/min, mass about 19500 g. Minimum axial load factor A 1.5 must be maintained in service.
What is the difference between 292, 293 and 294 series?
292 is the light, fastest section; 293 the medium; 294 the heaviest with the largest OD per bore and the greatest thrust capacity. 29256 is the high-speed 292 series, 280×380×60 mm.
What do E, EM and EF mean on 29256?
They are cage designs for different size bands: E is the stamped steel window cage of the current design, EM the machined brass cage for heavy/slow sizes, EF the steel cage for extra-large bearings — not quality grades. This bearing carries the steel cage of the earlier standard design.
Reviewed & verified by the MPN Base engineering desk against source catalog SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 13.1 spherical roller thrust bearings on 2026-09-27. Read our editorial & correction policy.