NK68-35 bearing: complete specifications & equivalents
The NK68-35 is a DIN 616 radial bearing sized 68 x 82 x 35 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 68 mm |
| Outer diameter D | 82 mm |
| Width B | 35 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | none |
| Basic dynamic load rating C | 60.5 kN |
| Basic static load rating C0 | 146 kN |
| Fatigue load limit Pu | 18.3 kN |
| Reference speed (thermal) | 6000 rpm |
| Limiting speed (mechanical) | 6700 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 340 g |
| Manufacturer designation | NK 68/35 |
| 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 | 2.677 in |
|---|---|
| Outer diameter D | 3.228 in |
| Width B | 1.378 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 7 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) | 36 of 46 |
| Bore above smallest NK-series size | 63 mm |
Cross references & equivalents
No verified interchange data yet. Send an inquiry and our team will confirm equivalents manually.
How the NK68-35 model number is decoded
SKF's machined-ring needle roller bearings without inner ring include NK 68/35: 68 mm Fw, 82 mm outside diameter, 35 mm width — a machined and ground outer ring whose rolled flanges retain the needle rollers, running on the shaft as the inner raceway. The NK 68/35 code states Fw 68 and width 35 mm directly; because the family has no inner ring, the 68 mm journal must be ground, hardened to 58–64 HRC and finished to the raceway tolerance the catalogue specifies. The machined ring is through-hardened and ground on OD, bore-side raceway and faces; the flanged lip design means the housing shoulder can be omitted — the ring clamps axially between housing wall and cover washer. Selection arithmetic: C 60.5 kN against C0 146 kN gives a C0/C ratio of 2.41, and the 18.3 kN fatigue load limit Pu sets the floor for the adjusted-life calculation at contaminated lubrication. Mounting: the flanged outer ring presses into the H7 housing bore against its flange face; the shaft (hardened to 58–64 HRC, ground) enters afterwards, and axial retention is by the housing wall plus a cover washer.
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
- abrasive paste formation from dust ingressing past open ends without effective housing seals
- rolling-contact fatigue spalling after the rated L10 life
- smearing of rollers and journal during idle periods because the radial section holds too little lubricant
Selection pitfalls — read before you substitute
- Above 50 mm bore, thermal growth matters: the 68 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.
- Hardness is load capacity: in families without an inner ring the 68 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 60.5/146 kN ratings are SKF catalogue values for this exact execution (NK 68/35); ratings can be revised without the order number changing, so keep the catalogue version (SKF catalogue PUB BU/P1 17000) with the drawing.
- The 60.5/146 kN ratings and 340 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 are the dimensions and ratings of the NK 68/35?
A NK 68/35 measures 68 mm bore/Fw × 82 mm outside diameter × 35 mm width (2.677 × 3.228 × 1.378 in). From SKF catalogue PUB BU/P1 17000: radial dynamic rating C 60.5 kN, static C0 146 kN, fatigue limit Pu 18.3 kN, limiting speed 6,700 r/min, reference speed 6,000 r/min, mass about 340 g.
How is the NK 68/35 designation read?
NK names a machined-ring needle roller bearing without inner ring: the figures give Fw 68 mm and width 35 mm, OD 82 mm comes from the dimension series, and the flanged outer ring retains the caged rollers.
Can the NK 68/35 run on an unhardened shaft?
No. In this execution the 68 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 68/35 be mounted?
Press on the ring faces only with a fitting sleeve, keep everything square to the 68 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.