NKIB5901 bearing: complete specifications & equivalents
The NKIB5901 is a DIN 616 radial bearing sized 12 x 24 x 17.5 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 | 17.5 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | none |
| Basic dynamic load rating C | 8.09 kN |
| Basic static load rating C0 | 9.65 kN |
| Fatigue load limit Pu | 1.14 kN |
| Reference speed (thermal) | 22000 rpm |
| Limiting speed (mechanical) | 26000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 43 g |
| Manufacturer designation | NKIB 5901 |
| 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 | 0.472 in |
|---|---|
| Outer diameter D | 0.945 in |
| Width B | 0.689 in |
| ISO bore code | 01 |
| Radial section height (D−d)/2 | 6 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) | 1 of 15 |
| Bore above smallest NKIB-series size | 0 mm |
Cross references & equivalents
No verified interchange data yet. Send an inquiry and our team will confirm equivalents manually.
How the NKIB5901 model number is decoded
SKF lists NKIB 5901 among the combined needle roller / three-point contact ball bearings: radial capacity from the needle roller set (8.09 kN C), axial capacity from the three-point contact ball part 2.07 kN (Ca), all within a 24×17.5 mm outline. Reading the designation: the letters combine the needle roller family with the ball execution — NKIB marks three-point contact — and 595901 the heavy 59 dimension series around the 12 mm bore. The combined unit is greased for life at assembly in many applications; relubrication, where provided, must reach both the roller cage and the ball set through the same axial bore features. Speed ceilings differ by part: 22,000 r/min thermal reference and 26,000 r/min limiting — the thrust element governs, since its washer faces see sliding components of contact. Life-lubricated as supplied in most sizes; where a relubrication path exists, meter grease gently — pressure through the 17.5 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
- needle edge loading and raceway denting when the shaft deflects beyond the compensation range
- polymer cage deformation when the local temperature exceeds the 120 °C sustained limit
- grease starvation at the roller ends when relubrication intervals are stretched in dirty duty
- hard-particle indentation in unfiltered lubricant
- thrust washer raceway wear from reverse axial shocks the one-direction thrust part cannot carry
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.
- Reference and limiting speeds are different limits: the 22,000 r/min reference is the thermal criterion under load, The limiting value is mechanical; the reference value is thermal under load, and grease choice moves it substantially.
- Hardness is load capacity: in families without an inner ring the 12 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 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 5901 facing the working thrust.
- Minimum axial load is a real requirement: below the catalogue minimum the thrust elements skid, polish their raceways and lose them — springs or preload washers belong in the arrangement drawing, not the troubleshooting notes.
- The 8.09/9.65 kN ratings and 43 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
Which dimensions does the NKIB 5901 have?
A NKIB 5901 measures 12 mm bore/Fw × 24 mm outside diameter × 17.5 mm width (0.472 × 0.945 × 0.689 in). From SKF catalogue PUB BU/P1 17000: radial dynamic rating C 8.09 kN, static C0 9.65 kN, fatigue limit Pu 1.14 kN, limiting speed 26,000 r/min, reference speed 22,000 r/min, mass about 43 g. Axial ratings of the ball part: dynamic Ca 2.07 kN (Ca), static C0a 1.92 kN (C0a); three-point contact geometry accepts axial load in both directions.
What does NKIB 5901 mean in SKF part numbering?
NKIB combines a needle roller cage with an three-point contact ball bearing in one unit; 595901 gives the series and 12 mm bore. The offset (s 16 mm) positions the ball raceway inside the 17.5 mm overall width.
Does the NKIB 5901 need a hardened and ground shaft?
The needle roller part of the NKIB 5901 rides directly on the 12 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.
What mounting mistakes ruin a NKIB 5901?
Press on the ring faces only with a fitting sleeve, keep everything square to the 12 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.