NK47-30 bearing: complete specifications & equivalents
The NK47-30 is a DIN 616 radial bearing sized 47 x 57 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 | 47 mm |
| Outer diameter D | 57 mm |
| Width B | 30 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | none |
| Basic dynamic load rating C | 41.8 kN |
| Basic static load rating C0 | 98 kN |
| Fatigue load limit Pu | 12.5 kN |
| Reference speed (thermal) | 8500 rpm |
| Limiting speed (mechanical) | 10000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 140 g |
| Manufacturer designation | NK 47/30 |
| Standard | DIN 616 |
| Catalog version | SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.3 machined rings with flanges, without an inner ring |
| Last verified | 2026-09-26 |
Source: catalog reference (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.3 machined rings with flanges, without 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. 7.3 machined rings with flanges, without 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 & NK-series range
| Bore d | 1.85 in |
|---|---|
| Outer diameter D | 2.244 in |
| Width B | 1.181 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 5 mm |
| Smallest bore in NK-series | 5 mm |
| Largest outer diameter in NK-series | 130 mm |
| Width range across NK-series | 10–40 mm |
| Bore position in NK-series (smallest first) | 31 of 46 |
| Bore above smallest NK-series size | 42 mm |
Cross references & equivalents
No verified interchange data yet. Send an inquiry and our team will confirm equivalents manually.
How the NK47-30 model number is decoded
NK 47/30 is a machined-ring needle roller bearing without an inner ring: a solid outer ring with integral flanges guiding the caged rollers, riding directly on a 47 mm hardened shaft journal, as listed in SKF catalogue PUB BU/P1 17000. The NK 47/30 code states Fw 47 and width 30 mm directly; because the family has no inner ring, the 47 mm journal must be ground, hardened to 58–64 HRC and finished to the raceway tolerance the catalogue specifies. SKF offers this family open as standard; a matching IR inner ring can be added separately when the shaft cannot be hardened, which converts the envelope into the NKI/NA equivalent. Selection arithmetic: C 41.8 kN against C0 98 kN gives a C0/C ratio of 2.34, and the 12.5 kN fatigue load limit Pu sets the floor for the adjusted-life calculation at contaminated lubrication. Fit the outer ring with a press and a fitting sleeve, not by hammering the flanges — rolled flanges chip; the 57 mm ground OD takes the press fit that prevents outer-ring creep in oscillating duty.
Typical equipment & failure modes
Common applications
- crank pins and eccentrics where the hardened journal is the raceway
- gearbox planetary and idler gears on hardened pins
- piston-pin style pivots in hydraulic pumps
- guide rollers running on hardened tracks
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
- false brinelling of standby equipment under external vibration
- rapid raceway scoring when the shaft journal hardness drops below 58 HRC or the ground finish wears away
Selection pitfalls — read before you substitute
- At 47 mm bore, verify shaft deflection against the needle length: these rollers tolerate little edge loading, and a simply supported span between 47 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 47 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 41.8/98 kN ratings are SKF catalogue values for this exact execution (NK 47/30); ratings can be revised without the order number changing, so keep the catalogue version (SKF catalogue PUB BU/P1 17000) with the drawing.
- The 41.8/98 kN ratings and 140 g mass are SKF catalogue values transcribed from ch. 7.3 of PUB BU/P1 17000 (PDF table page 632); combined-type axial ratings appear in the text above because the structured record carries radial values only.
Frequently asked questions
What limits the service life of a NK 47/30?
Beyond the L10 rating, the practical limits are journal/raceway hardness for the 47 mm seat, lubricant condition at the roller ends, and contamination through open ends — the 5.0 mm radial section leaves no reserve once a raceway is dented or ribboned.
What are the dimensions and ratings of the NK 47/30?
A NK 47/30 measures 47 mm bore/Fw × 57 mm outside diameter × 30 mm width (1.85 × 2.244 × 1.181 in). From SKF catalogue PUB BU/P1 17000: radial dynamic rating C 41.8 kN, static C0 98 kN, fatigue limit Pu 12.5 kN, limiting speed 10,000 r/min, reference speed 8,500 r/min, mass about 140 g.
How is the NK 47/30 designation read?
NK names a machined-ring needle roller bearing without inner ring: the figures give Fw 47 mm and width 30 mm, OD 57 mm comes from the dimension series, and the flanged outer ring retains the caged rollers.
Can the NK 47/30 run on an unhardened shaft?
No. In this execution the 47 mm shaft journal is the inner raceway: it must be ground and hardened to 58–64 HRC (with matching housing bore quality on the outside). If the shaft cannot meet that, order the inner-ring sibling (NKI/NA execution) plus its ground inner ring instead.
Reviewed & verified by the MPN Base engineering desk against source catalog SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.3 machined rings with flanges, without an inner ring on 2026-09-26. Read our editorial & correction policy.