NKX70-Z bearing: complete specifications & equivalents
The NKX70-Z is a DIN 616 radial bearing sized 70 x 85 x 40 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 | 85 mm |
| Width B | 40 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | none |
| Basic dynamic load rating C | 44.6 kN |
| Basic static load rating C0 | 98 kN |
| Fatigue load limit Pu | 12.2 kN |
| Reference speed (thermal) | 3400 rpm |
| Limiting speed (mechanical) | 2700 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 520 g |
| Manufacturer designation | NKX 70 Z |
| Standard | DIN 616 |
| Catalog version | SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.9 needle roller / thrust ball, caged thrust part |
| Last verified | 2026-09-26 |
Source: catalog reference (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.9 needle roller / thrust ball, caged thrust part) · extracted 2026-09-26
Parameters extracted from the official SKF Rolling Bearings catalogue (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.9 needle roller / thrust ball, caged thrust part); 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 & NKX-series range
| Bore d | 2.756 in |
|---|---|
| Outer diameter D | 3.346 in |
| Width B | 1.575 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 7.5 mm |
| Smallest bore in NKX-series | 10 mm |
| Largest outer diameter in NKX-series | 85 mm |
| Width range across NKX-series | 23–40 mm |
| Bore position in NKX-series (smallest first) | 13 of 13 |
| Bore above smallest NKX-series size | 60 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| NKX70 | SKF | full Dimensions and internal design equivalent — standard interchange. | Same 70×85×40 mm envelope and equivalent catalogue ratings; NKX70 is the combined needle/thrust ball execution — boundary-dimension interchangeable, execution differences (seals, shields, cage) apply. |
Interchange levels: full standard interchange · partial verify parameters · verify manual confirmation required. Links resolve to the equivalent model's specification page where available.
How the NKX70-Z model number is decoded
NKX 70 Z is a combined needle roller / thrust ball bearing with a caged thrust part: radial load on caged needle rollers, axial load on a ball thrust set with stamped cages, per SKF catalogue PUB BU/P1 17000 ch. 7.9. The code NKX 70 Z reads as combined radial/thrust for a 70 mm shaft; the catalogue height 40 mm stacks the radial cage and the thrust set, and the 85 mm OD seats both parts in one bore. Execution notes: the Z suffix adds a shield over the thrust balls, TN a polymer cage; the open execution allows relubrication through the shaft, the Z execution is greased for life. Speed ceilings differ by part: 3,400 r/min thermal reference and 2,700 r/min limiting — the thrust element governs, since its washer faces see sliding components of contact. Mounting: press the unit onto the 70 mm seat against the inner faces, orient the thrust set toward the axial load, and verify the 40 mm overall height against the housing stack after fitting.
Typical equipment & failure modes
Common applications
- gear pairs generating one-direction axial force
- rotary indexing tables under combined load
- conveyor screw thrust ends
- turntable and swivel mounts
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
- rolling-contact fatigue spalling after the rated L10 life
- thrust-part ball or roller skidding and smearing when the axial load falls below the minimum factor
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.
- Hardness is load capacity: in families without an inner ring the 70 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 44.6/98 kN ratings are SKF catalogue values for this exact execution (NKX 70 Z); ratings can be revised without the order number changing, so keep the catalogue version (SKF catalogue PUB BU/P1 17000) with the drawing.
- Do not treat the axial rating 43.6 kN (Ca) as independent of radial load: the combined equivalent load formulas couple them, and a unit sized on radial life alone will spall the ball raceway first under real thrust.
- The thrust part is one-direction: reverse axial events — however brief — lift the rolling elements off the raceway, and the subsequent re-entry impact dents the washer face; mount the NKX 70 Z facing the working thrust.
- The 44.6/98 kN ratings and 520 g mass are SKF catalogue values transcribed from ch. 7.9 of PUB BU/P1 17000 (PDF table page 658); combined-type axial ratings appear in the text above because the structured record carries radial values only.
Frequently asked questions
Can the NKX 70 Z run on an unhardened shaft?
The radial needle part of the NKX 70 Z runs directly on the 70 mm journal — harden to 58–64 HRC and grind it. The thrust washers are integral, so no separate inner ring exists; size the shaft for the raceway tolerances in the catalogue table.
How should the NKX 70 Z be mounted?
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.
What limits the service life of a NKX 70 Z?
Beyond the L10 rating, the practical limits are journal/raceway hardness for the 70 mm seat, lubricant condition at the roller ends, and contamination through open ends — the 7.5 mm radial section leaves no reserve once a raceway is dented or ribboned.
What are the dimensions and ratings of the NKX 70 Z?
A NKX 70 Z measures 70 mm bore/Fw × 85 mm outside diameter × 40 mm width (2.756 × 3.346 × 1.575 in). From SKF catalogue PUB BU/P1 17000: radial dynamic rating C 44.6 kN, static C0 98 kN, fatigue limit Pu 12.2 kN, limiting speed 2,700 r/min, reference speed 3,400 r/min, mass about 520 g. Axial ratings of the thrust part: dynamic Ca 43.6 kN (Ca), static C0a 137 kN (C0a), minimum load factor A 0.097; the thrust set carries load in one direction only.
Reviewed & verified by the MPN Base engineering desk against source catalog SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.9 needle roller / thrust ball, caged thrust part on 2026-09-26. Read our editorial & correction policy.