NKIB5908 bearing: complete specifications & equivalents
The NKIB5908 is a DIN 616 radial bearing sized 40 x 62 x 34 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 40 mm |
| Outer diameter D | 62 mm |
| Width B | 34 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | none |
| Basic dynamic load rating C | 42.9 kN |
| Basic static load rating C0 | 71 kN |
| Fatigue load limit Pu | 8.8 kN |
| Reference speed (thermal) | 8000 rpm |
| Limiting speed (mechanical) | 9500 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 320 g |
| Manufacturer designation | NKIB 5908 |
| 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 | 1.575 in |
|---|---|
| Outer diameter D | 2.441 in |
| Width B | 1.339 in |
| ISO bore code | 08 |
| Radial section height (D−d)/2 | 11 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) | 9 of 15 |
| Bore above smallest NKIB-series size | 28 mm |
Cross references & equivalents
No verified interchange data yet. Send an inquiry and our team will confirm equivalents manually.
How the NKIB5908 model number is decoded
For shafts where a separate thrust bearing would lengthen the assembly, NKIB 5908 integrates needle rollers and an three-point contact ball bearing: 40 mm bore, 62 mm OD, 34 mm overall width including the ball set offset. The designation NKIB 5908 identifies the two rolling elements in one unit; the 40 mm bore and 62 mm OD come from the 59-series plan, and the 34 mm width stacks roller set plus ball set. NKIB three-point contact ball raceways accept axial load in both directions, while NKIA angular contact ball raceways lean the axial capacity toward one direction — check the load direction before ordering either. Selection arithmetic for the combined unit: radial C 42.9 kN, radial C0 71 kN, axial dynamic 7.17 kN (Ca) and axial static 10.9 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 34 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 40 mm bore, verify shaft deflection against the needle length: these rollers tolerate little edge loading, and a simply supported span between 40 mm seats can bend past the compensation range long before the load rating is exhausted.
- Do not interchange envelope-identical needle families blindly: NKIB 5908 shares its 40×62×34 mm outline with inner-ring and sealed siblings whose ratings differ — the family letters are part of the specification, not decoration.
- Reference and limiting speeds are different limits: the 8,000 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.
- 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.
- Height stack-up is easy to mis-check: the ball-raceway part adds height beyond a plain needle bearing, and clamping the stack solid over it preloads the thrust set beyond its rating.
- The 42.9/71 kN ratings and 320 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
How should the NKIB 5908 be mounted?
Press on the ring faces only with a fitting sleeve, keep everything square to the 40 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.
What limits the service life of a NKIB 5908?
Beyond the L10 rating, the practical limits are journal/raceway hardness for the 40 mm seat, lubricant condition at the roller ends, and contamination through open ends — the 11.0 mm radial section leaves no reserve once a raceway is dented or ribboned.
What are the dimensions and ratings of the NKIB 5908?
A NKIB 5908 measures 40 mm bore/Fw × 62 mm outside diameter × 34 mm width (1.575 × 2.441 × 1.339 in). From SKF catalogue PUB BU/P1 17000: radial dynamic rating C 42.9 kN, static C0 71 kN, fatigue limit Pu 8.8 kN, limiting speed 9,500 r/min, reference speed 8,000 r/min, mass about 320 g. Axial ratings of the ball part: dynamic Ca 7.17 kN (Ca), static C0a 10.9 kN (C0a); three-point contact geometry accepts axial load in both directions.
How is the NKIB 5908 designation read?
NKIB combines a needle roller cage with an three-point contact ball bearing in one unit; 595908 gives the series and 40 mm bore. The offset (s 30 mm) positions the ball raceway inside the 34 mm overall width.
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.