NKIA5909 bearing: complete specifications & equivalents
The NKIA5909 is a DIN 616 radial bearing sized 45 x 68 x 30 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 45 mm |
| Outer diameter D | 68 mm |
| Width B | 30 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | none |
| Basic dynamic load rating C | 45.7 kN |
| Basic static load rating C0 | 78 kN |
| Fatigue load limit Pu | 9.65 kN |
| Reference speed (thermal) | 7500 rpm |
| Limiting speed (mechanical) | 8500 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 380 g |
| Manufacturer designation | NKIA 5909 |
| 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 & NKIA-series range
| Bore d | 1.772 in |
|---|---|
| Outer diameter D | 2.677 in |
| Width B | 1.181 in |
| ISO bore code | 09 |
| Radial section height (D−d)/2 | 11.5 mm |
| Smallest bore in NKIA-series | 12 mm |
| Largest outer diameter in NKIA-series | 100 mm |
| Width range across NKIA-series | 16–40 mm |
| Bore position in NKIA-series (smallest first) | 10 of 15 |
| Bore above smallest NKIA-series size | 33 mm |
Cross references & equivalents
No verified interchange data yet. Send an inquiry and our team will confirm equivalents manually.
How the NKIA5909 model number is decoded
In SKF catalogue PUB BU/P1 17000, NKIA 5909 designates a combined bearing of the combined needle roller / angular contact ball bearings: caged needle rollers for the 45 mm radial seat share a shaft with an integral angular contact ball set rated 7.47 kN (Ca) axially. The NKIA 5909 code breaks into series letters (needle roller + ball), dimension series 59, and the two-digit bore reference for 45 mm; the 30 mm width covers both the roller cage and the offset ball set (offset per catalogue s column). Execution notes: the ball set runs on a raceway offset by a catalogue-listed offset 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. Speed ceilings differ by part: 7,500 r/min thermal reference and 8,500 r/min limiting — the thrust element governs, since its washer faces see sliding components of contact. Fit the combined unit so the ball raceway offset faces the working axial load, check rotation in both directions, and preload if required with the washer stack the catalogue recommends.
Typical equipment & failure modes
Common applications
- spindle heads needing compact radial-plus-axial support
- lead-screw and ball-screw support positions
- pump rotors with hydraulic axial pull
- bevel gear shafts with moderate axial force
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
- abrasive paste formation from dust ingressing past open ends without effective housing seals
- false brinelling of standby equipment under external vibration
- thrust washer raceway wear from reverse axial shocks the one-direction thrust part cannot carry
Selection pitfalls — read before you substitute
- At 45 mm bore, verify shaft deflection against the needle length: these rollers tolerate little edge loading, and a simply supported span between 45 mm seats can bend past the compensation range long before the load rating is exhausted.
- Do not interchange envelope-identical needle families blindly: NKIA 5909 shares its 45×68×30 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 7,500 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 45.7/78 kN ratings and 380 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 is the NKIA 5909 designation read?
NKIA combines a needle roller cage with an angular contact ball bearing in one unit; 595909 gives the series and 45 mm bore. The offset (a catalogue-listed offset) positions the ball raceway inside the 30 mm overall width.
Can the NKIA 5909 run on an unhardened shaft?
The needle roller part of the NKIA 5909 rides directly on the 45 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 NKIA 5909 be mounted?
Press on the ring faces only with a fitting sleeve, keep everything square to the 45 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 NKIA 5909?
Beyond the L10 rating, the practical limits are journal/raceway hardness for the 45 mm seat, lubricant condition at the roller ends, and contamination through open ends — the 11.5 mm radial section leaves no reserve once a raceway is dented or ribboned.
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.