NK85-25 bearing: complete specifications & equivalents
The NK85-25 is a DIN 616 radial bearing sized 85 x 105 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 | 85 mm |
| Outer diameter D | 105 mm |
| Width B | 25 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | none |
| Basic dynamic load rating C | 69.3 kN |
| Basic static load rating C0 | 132 kN |
| Fatigue load limit Pu | 16.6 kN |
| Reference speed (thermal) | 4800 rpm |
| Limiting speed (mechanical) | 5300 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 430 g |
| Manufacturer designation | NK 85/25 |
| 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 | 3.346 in |
|---|---|
| Outer diameter D | 4.134 in |
| Width B | 0.984 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 10 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) | 41 of 46 |
| Bore above smallest NK-series size | 80 mm |
Cross references & equivalents
No verified interchange data yet. Send an inquiry and our team will confirm equivalents manually.
How the NK85-25 model number is decoded
In SKF catalogue PUB BU/P1 17000, NK 85/25 designates a flanged, machined outer ring filled with needle rollers and a cage for a 85 mm shaft — heavier section and higher accuracy than a drawn cup, with no inner ring so the journal is the raceway. The NK 85/25 code states Fw 85 and width 25 mm directly; because the family has no inner ring, the 85 mm journal must be ground, hardened to 58–64 HRC and finished to the raceway tolerance the catalogue specifies. The wide NKS/NKIS siblings share the Fw and OD but add width for higher ratings — check both when the radial space allows a wider seat. For life calculation, the 69.3/132 kN ratings assume raceway geometry supplied by the shaft and housing in families without an inner ring — journal hardness, roundness and finish are part of the bearing, not of the application. Fit the outer ring with a press and a fitting sleeve, not by hammering the flanges — rolled flanges chip; the 105 mm ground OD takes the press fit that prevents outer-ring creep in oscillating duty.
Typical equipment & failure modes
Common applications
- guide rollers running on hardened tracks
- swing arms and lever pivots with oscillating duty
- cam followers built up from separate components
- crank pins and eccentrics where the hardened journal is the raceway
Known failure patterns
- raceway spalling once the catalogue L10 life is exceeded or after overload events
- polymer cage deformation when the local temperature exceeds the 120 °C sustained limit
- abrasive paste formation from dust ingressing past open ends without effective housing seals
- brinelling of raceways from impact or pressing force transmitted through the rolling elements
- rapid raceway scoring when the shaft journal hardness drops below 58 HRC or the ground finish wears away
Selection pitfalls — read before you substitute
- Above 50 mm bore, thermal growth matters: the 85 mm inner ring or journal grows with temperature faster than the housing, and the small clearance of a needle roller contact leaves little reserve — check running clearance hot, not just at assembly.
- Do not interchange envelope-identical needle families blindly: NK 85/25 shares its 85×105×25 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 4,800 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.
- The 69.3/132 kN ratings and 430 g mass are SKF catalogue values transcribed from ch. 7.3 of PUB BU/P1 17000 (PDF table page 634); 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 NK 85/25?
A NK 85/25 measures 85 mm bore/Fw × 105 mm outside diameter × 25 mm width (3.346 × 4.134 × 0.984 in). From SKF catalogue PUB BU/P1 17000: radial dynamic rating C 69.3 kN, static C0 132 kN, fatigue limit Pu 16.6 kN, limiting speed 5,300 r/min, reference speed 4,800 r/min, mass about 430 g.
How is the NK 85/25 designation read?
NK names a machined-ring needle roller bearing without inner ring: the figures give Fw 85 mm and width 25 mm, OD 105 mm comes from the dimension series, and the flanged outer ring retains the caged rollers.
Can the NK 85/25 run on an unhardened shaft?
No. In this execution the 85 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.
How should the NK 85/25 be mounted?
Press on the ring faces only with a fitting sleeve, keep everything square to the 85 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. 7.3 machined rings with flanges, without an inner ring on 2026-09-26. Read our editorial & correction policy.