NKS70 bearing: complete specifications & equivalents
The NKS70 is a DIN 616 radial bearing sized 70 x 90 x 28 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 70 mm |
| Outer diameter D | 90 mm |
| Width B | 28 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | none |
| Basic dynamic load rating C | 68.2 kN |
| Basic static load rating C0 | 120 kN |
| Fatigue load limit Pu | 15.3 kN |
| Reference speed (thermal) | 5600 rpm |
| Limiting speed (mechanical) | 6300 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 380 g |
| Manufacturer designation | NKS 70 |
| 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 & NKS-series range
| Bore d | 2.756 in |
|---|---|
| Outer diameter D | 3.543 in |
| Width B | 1.102 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 10 mm |
| Smallest bore in NKS-series | 20 mm |
| Largest outer diameter in NKS-series | 95 mm |
| Width range across NKS-series | 20–28 mm |
| Bore position in NKS-series (smallest first) | 16 of 17 |
| Bore above smallest NKS-series size | 50 mm |
Cross references & equivalents
No verified interchange data yet. Send an inquiry and our team will confirm equivalents manually.
How the NKS70 model number is decoded
NKS 70 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 70 mm hardened shaft journal, as listed in SKF catalogue PUB BU/P1 17000. In SKF nomenclature NKS families drop the inner ring: the numbers after the letters give the 70 mm under-roller diameter and the 28 mm width, with the 90 mm outside diameter set by the wide-section machined-ring needle roller bearings without inner ring plan. 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. Minimum load matters: below roughly 0.02·C the rollers skid and smear; preloading the pivot or specifying a heavier execution avoids the glazing that pure oscillation produces on these raceways. Grease through the housing groove before fitting the shaft; the integral flanges hold the grease film at the roller ends, which is where these bearings first starve.
Typical equipment & failure modes
Common applications
- 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
- gearbox planetary and idler gears on hardened pins
Known failure patterns
- needle edge loading and raceway denting when the shaft deflects beyond the compensation range
- 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
- hard-particle indentation in unfiltered lubricant
- 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 70 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.
- Contamination, not fatigue, kills most small needle bearings: with raceways this narrow, one hard particle dents a full-width line — seal the housing even when the bearing execution itself is open.
- Do not interchange envelope-identical needle families blindly: NKS 70 shares its 70×90×28 mm outline with inner-ring and sealed siblings whose ratings differ — the family letters are part of the specification, not decoration.
- The 68.2/120 kN ratings and 380 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
Does the NKS 70 need a hardened and ground shaft?
No. In this execution the 70 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.
What mounting mistakes ruin a NKS 70?
Press on the ring faces only with a fitting sleeve, keep everything square to the 70 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.
Is the NKS 70 sealed?
No — this execution is open and depends on the housing sealing arrangement; grease it at assembly and keep the relubrication interval short in dirty duty.
Which dimensions does the NKS 70 have?
A NKS 70 measures 70 mm bore/Fw × 90 mm outside diameter × 28 mm width (2.756 × 3.543 × 1.102 in). From SKF catalogue PUB BU/P1 17000: radial dynamic rating C 68.2 kN, static C0 120 kN, fatigue limit Pu 15.3 kN, limiting speed 6,300 r/min, reference speed 5,600 r/min, mass about 380 g.
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.