NKIB5906 bearing: complete specifications & equivalents
The NKIB5906 is a DIN 616 radial bearing sized 30 x 47 x 25 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 30 mm |
| Outer diameter D | 47 mm |
| Width B | 25 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | none |
| Basic dynamic load rating C | 25.5 kN |
| Basic static load rating C0 | 39 kN |
| Fatigue load limit Pu | 4.65 kN |
| Reference speed (thermal) | 11000 rpm |
| Limiting speed (mechanical) | 13000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 150 g |
| Manufacturer designation | NKIB 5906 |
| Standard | DIN 616 |
| Catalog version | SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.7 needle roller / angular contact ball bearings |
| Last verified | 2026-09-26 |
Source: catalog reference (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.7 needle roller / angular contact ball bearings) · extracted 2026-09-26
Parameters extracted from the official SKF Rolling Bearings catalogue (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.7 needle roller / angular contact ball 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 & NKIB-series range
| Bore d | 1.181 in |
|---|---|
| Outer diameter D | 1.85 in |
| Width B | 0.984 in |
| ISO bore code | 06 |
| Radial section height (D−d)/2 | 8.5 mm |
| Smallest bore in NKIB-series | 12 mm |
| Largest outer diameter in NKIB-series | 100 mm |
| Width range across NKIB-series | 17.5–45 mm |
| Bore position in NKIB-series (smallest first) | 7 of 15 |
| Bore above smallest NKIB-series size | 18 mm |
Cross references & equivalents
No verified interchange data yet. Send an inquiry and our team will confirm equivalents manually.
How the NKIB5906 model number is decoded
NKIB 5906 solves compact radial-plus-thrust duty: a needle roller cage and an three-point contact ball bearing built into one 25 mm wide unit with a 30 mm bore and 47 mm outside diameter. The NKIB 5906 code breaks into series letters (needle roller + ball), dimension series 59, and the two-digit bore reference for 30 mm; the 25 mm width covers both the roller cage and the offset ball set (s offset 23 mm). Execution notes: the ball set runs on a raceway offset by s 23 mm from the roller set centreline — this offset is why the overall width exceeds a plain needle bearing and why the units cannot be dismantled without losing preload. Selection arithmetic for the combined unit: radial C 25.5 kN, radial C0 39 kN, axial dynamic 4.54 kN (Ca) and axial static 6.32 kN (C0a); combine them with the equivalent-load factors from the catalogue before checking L10. Life-lubricated as supplied in most sizes; where a relubrication path exists, meter grease gently — pressure through the 25 mm wide unit can lift the seals of adjacent components.
Typical equipment & failure modes
Common applications
- gearbox main shafts carrying radial plus one-direction thrust
- worm gear shafts with axial reaction toward the worm
- spindle heads needing compact radial-plus-axial support
- lead-screw and ball-screw support positions
Known failure patterns
- raceway spalling once the catalogue L10 life is exceeded or after overload events
- cage pocket wear and roller skew after sustained operation with too little radial preload
- grease starvation at the roller ends when relubrication intervals are stretched in dirty duty
- electrical erosion on VFD-driven shafts without brush or insulated mounting
- thrust-part ball or roller skidding and smearing when the axial load falls below the minimum factor
Selection pitfalls — read before you substitute
- At 30 mm bore, verify shaft deflection against the needle length: these rollers tolerate little edge loading, and a simply supported span between 30 mm seats can bend past the compensation range long before the load rating is exhausted.
- Hardness is load capacity: in families without an inner ring the 30 mm journal must hold 58–64 HRC with a ground finish; a surface that looks fine but sits at 45 HRC will rib the raceway within weeks.
- The quoted 25.5/39 kN ratings are SKF catalogue values for this exact execution (NKIB 5906); ratings can be revised without the order number changing, so keep the catalogue version (SKF catalogue PUB BU/P1 17000) with the drawing.
- Do not treat the axial rating 4.54 kN (Ca) as independent of radial load: the combined equivalent load formulas couple them, and a unit sized on radial life alone will spall the ball raceway first under real thrust.
- The thrust part is one-direction: reverse axial events — however brief — lift the rolling elements off the raceway, and the subsequent re-entry impact dents the washer face; mount the NKIB 5906 facing the working thrust.
- The 25.5/39 kN ratings and 150 g mass are SKF catalogue values transcribed from ch. 7.7 of PUB BU/P1 17000 (PDF table page 654); 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 NKIB 5906?
A NKIB 5906 measures 30 mm bore/Fw × 47 mm outside diameter × 25 mm width (1.181 × 1.85 × 0.984 in). From SKF catalogue PUB BU/P1 17000: radial dynamic rating C 25.5 kN, static C0 39 kN, fatigue limit Pu 4.65 kN, limiting speed 13,000 r/min, reference speed 11,000 r/min, mass about 150 g. Axial ratings of the ball part: dynamic Ca 4.54 kN (Ca), static C0a 6.32 kN (C0a); three-point contact geometry accepts axial load in both directions.
How is the NKIB 5906 designation read?
NKIB combines a needle roller cage with an three-point contact ball bearing in one unit; 595906 gives the series and 30 mm bore. The offset (s 23 mm) positions the ball raceway inside the 25 mm overall width.
Can the NKIB 5906 run on an unhardened shaft?
The needle roller part of the NKIB 5906 rides directly on the 30 mm journal, so it must be hardened to 58–64 HRC and ground; the ball set runs on its own integrated raceways. There is no inner-ring variant — harden the shaft or move to a separate bearing arrangement.
How should the NKIB 5906 be mounted?
Press on the ring faces only with a fitting sleeve, keep everything square to the 30 mm seat, and never transmit force through the rolling elements. Follow the catalogue's seat tolerances — the narrow needle contact forgives neither tilt nor burrs.
Reviewed & verified by the MPN Base engineering desk against source catalog SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.7 needle roller / angular contact ball bearings on 2026-09-26. Read our editorial & correction policy.