NA4901 bearing: complete specifications & equivalents
The NA4901 is a ISO 1206 radial bearing sized 12 x 24 x 13 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 12 mm |
| Outer diameter D | 24 mm |
| Width B | 13 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | none |
| Basic dynamic load rating C | 9.9 kN |
| Basic static load rating C0 | 12.2 kN |
| Fatigue load limit Pu | 1.46 kN |
| Reference speed (thermal) | 22000 rpm |
| Limiting speed (mechanical) | 26000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 26 g |
| Manufacturer designation | NA 4901 |
| Standard | ISO 1206 |
| Catalog version | SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.4 machined rings with flanges, with an inner ring |
| Last verified | 2026-09-26 |
Source: catalog reference (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.4 machined rings with flanges, with an inner ring) · extracted 2026-09-26
Parameters extracted from the official SKF Rolling Bearings catalogue (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.4 machined rings with flanges, with an inner ring); 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 & NA-49-series range
| Bore d | 0.472 in |
|---|---|
| Outer diameter D | 0.945 in |
| Width B | 0.512 in |
| ISO bore code | 01 |
| Radial section height (D−d)/2 | 6 mm |
| Smallest bore in NA-49-series | 10 mm |
| Largest outer diameter in NA-49-series | 190 mm |
| Width range across NA-49-series | 13–50 mm |
| Bore position in NA-49-series (smallest first) | 2 of 28 |
| Bore above smallest NA-49-series size | 2 mm |
Cross references & equivalents
No verified interchange data yet. Send an inquiry and our team will confirm equivalents manually.
How the NA4901 model number is decoded
NA 4901 is a machined-ring needle roller bearing with an inner ring: flanged outer ring plus a separate 12 mm bore inner ring, so the shaft seat needs only ordinary tolerance, as tabulated by SKF in SKF catalogue PUB BU/P1 17000. The NA 4901 code gives bore 12 mm and width 13 mm explicitly; unlike the RNA/NK families the shaft only needs a standard k5/j5 seat because the hardened inner ring is the raceway. TN polymer cage executions run quieter and tolerate grease-lubricated pivot duty; steel cage executions remain the choice for higher temperature or oil-bath lubrication. Catalogue mass 26 g at 12×24×13 mm makes this one of the highest capacity-per-gram choices in the dimension series 49 needle roller bearings with inner ring; the limit is usually the shaft's ability to serve as a raceway, not the rolling contact itself. Because the inner ring is separable, mount it first against its shoulder, then slide the outer ring and roller set over it — the order avoids forcing rollers across the shaft threads or burrs.
Typical equipment & failure modes
Common applications
- printing and paper-handling rollers
- gearbox shafts where the journal cannot be hardened on site
- wheel and lever pivots needing a replaceable inner ring
- conveyor roller ends and return rollers
Known failure patterns
- raceway spalling once the catalogue L10 life is exceeded or after overload events
- polymer cage deformation when the local temperature exceeds the 120 °C sustained limit
- abrasive paste formation from dust ingressing past open ends without effective housing seals
- brinelling of raceways from impact or pressing force transmitted through the rolling elements
- inner-ring bore fretting on a loose shaft seat, migrating hard particles into the rolling contact
Selection pitfalls — read before you substitute
- On a 12 mm seat the housing bore quality dominates life: a bore 0.02 mm out of round pinches the 24 mm ring or cup into a lobed shape, and the rollers then trace the housing's geometry error, not the design load.
- Oscillating pivots fail differently: rocking through a small angle concentrates wear in the same roller positions — inspect those zones, and consider rotating the assembly's clock position at service intervals.
- Contamination, not fatigue, kills most small needle bearings: with raceways this narrow, one hard particle dents a full-width line — seal the housing even when the bearing execution itself is open.
- The 9.9/12.2 kN ratings and 26 g mass are SKF catalogue values transcribed from ch. 7.4 of PUB BU/P1 17000 (PDF table page 638); combined-type axial ratings appear in the text above because the structured record carries radial values only.
Frequently asked questions
What are the dimensions and ratings of the NA 4901?
A NA 4901 measures 12 mm bore/Fw × 24 mm outside diameter × 13 mm width (0.472 × 0.945 × 0.512 in). From SKF catalogue PUB BU/P1 17000: radial dynamic rating C 9.9 kN, static C0 12.2 kN, fatigue limit Pu 1.46 kN, limiting speed 26,000 r/min, reference speed 22,000 r/min, mass about 26 g.
How is the NA 4901 designation read?
The letters mark a machined-ring needle roller bearing with inner ring: 12 mm bore, 13 mm width, 24 mm OD per the series plan. The hardened inner ring is the raceway, so an ordinary k5 shaft seat suffices.
Can the NA 4901 run on an unhardened shaft?
Yes — that is the point of this family. The NA 4901 carries its own hardened, ground inner ring on a 12 mm seat, so the shaft needs only a normal k5/j6 finish. The inner ring is separable and replaceable.
How should the NA 4901 be mounted?
Mount the inner ring on the 12 mm seat first (induction heat, max 120 °C, or press), then fit the flanged outer ring into the H7 housing bore. Verify free rotation and, for 2RS executions, check the wider outer ring against the housing depth.
Reviewed & verified by the MPN Base engineering desk against source catalog SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.4 machined rings with flanges, with an inner ring on 2026-09-26. Read our editorial & correction policy.