NKXR20 bearing: complete specifications & equivalents
The NKXR20 is a DIN 616 radial bearing sized 20 x 30 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 | 20 mm |
| Outer diameter D | 30 mm |
| Width B | 30 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | none |
| Basic dynamic load rating C | 16.5 kN |
| Basic static load rating C0 | 25.5 kN |
| Fatigue load limit Pu | 3.05 kN |
| Reference speed (thermal) | 3800 rpm |
| Limiting speed (mechanical) | 7500 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 80 g |
| Manufacturer designation | NKXR 20 |
| Standard | DIN 616 |
| Catalog version | SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.10 needle roller / cylindrical-needle thrust |
| Last verified | 2026-09-26 |
Source: catalog reference (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.10 needle roller / cylindrical-needle thrust) · extracted 2026-09-26
Parameters extracted from the official SKF Rolling Bearings catalogue (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.10 needle roller / cylindrical-needle thrust); 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 & NKXR-series range
| Bore d | 0.787 in |
|---|---|
| Outer diameter D | 1.181 in |
| Width B | 1.181 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 5 mm |
| Smallest bore in NKXR-series | 15 mm |
| Largest outer diameter in NKXR-series | 62 mm |
| Width range across NKXR-series | 23–35 mm |
| Bore position in NKXR-series (smallest first) | 3 of 9 |
| Bore above smallest NKXR-series size | 5 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| NKXR20-Z | SKF | full Dimensions and internal design equivalent — standard interchange. | Same 20×30×30 mm envelope and equivalent catalogue ratings; NKXR20-Z is the combined needle/thrust needle execution — boundary-dimension interchangeable, execution differences (seals, shields, cage) apply. |
| NKX20-Z | SKF | full Dimensions and internal design equivalent — standard interchange. | Envelope-identical (20×30×30 mm) combined needle/thrust ball execution with ratings within 10 % — substitution possible after checking ring/flange construction. |
| NKX20 | SKF | full Dimensions and internal design equivalent — standard interchange. | Envelope-identical (20×30×30 mm) combined needle/thrust ball execution with ratings within 10 % — substitution possible after checking ring/flange construction. |
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 NKXR20 model number is decoded
The combined needle roller / full complement needle thrust bearings execution NKXR 20 measures 20×30×30 mm: radial dynamic 16.5 kN, axial dynamic 18.6 kN (Ca) — the thrust needle complement gives roughly twice the axial rating of a same-size thrust ball part. The R before the X in NKXR flags the roller (not ball) thrust part; the figure gives the 20 mm seat, and the catalogue completes 30×30 mm. One-direction thrust only — reverse axial loads lift the packed needle set off its raceway; arrange a second unit mirrored or a separate thrust bearing for reversing duty. Selection arithmetic for the combined unit: radial C 16.5 kN, radial C0 25.5 kN, axial dynamic 18.6 kN (Ca) and axial static 48 kN (C0a); combine them with the equivalent-load factors from the catalogue before checking L10. Mounting: the thrust needle complement is held by grease during assembly; fill the washer set, orient toward the axial load, and preload to at least factor A 0.00018 before rotating.
Typical equipment & failure modes
Common applications
- turntables and slewing pivots with shock loads
- press-fit die set guide positions
- heavy screw presses and clamping spindles
- crane slew rings and kingposts at low speed
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
- thrust washer raceway wear from reverse axial shocks the one-direction thrust part cannot carry
Selection pitfalls — read before you substitute
- On a 20 mm seat the housing bore quality dominates life: a bore 0.02 mm out of round pinches the 30 mm ring or cup into a lobed shape, and the rollers then trace the housing's geometry error, not the design load.
- Do not interchange envelope-identical needle families blindly: NKXR 20 shares its 20×30×30 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 3,800 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.
- Do not treat the axial rating 18.6 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 NKXR 20 facing the working thrust.
- The 16.5/25.5 kN ratings and 80 g mass are SKF catalogue values transcribed from ch. 7.10 of PUB BU/P1 17000 (PDF table page 660); combined-type axial ratings appear in the text above because the structured record carries radial values only.
Frequently asked questions
How should the NKXR 20 be mounted?
Press on the ring faces only with a fitting sleeve, keep everything square to the 20 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 NKXR 20?
Beyond the L10 rating, the practical limits are journal/raceway hardness for the 20 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 NKXR 20?
A NKXR 20 measures 20 mm bore/Fw × 30 mm outside diameter × 30 mm width (0.787 × 1.181 × 1.181 in). From SKF catalogue PUB BU/P1 17000: radial dynamic rating C 16.5 kN, static C0 25.5 kN, fatigue limit Pu 3.05 kN, limiting speed 7,500 r/min, reference speed 3,800 r/min, mass about 80 g. Axial ratings of the thrust part: dynamic Ca 18.6 kN (Ca), static C0a 48 kN (C0a), minimum load factor A 0.00018; the thrust set carries load in one direction only.
How is the NKXR 20 designation read?
NKXR = needle roller radial part + full complement needle thrust part for a 20 mm shaft: 30 mm OD, 30 mm overall height, the highest axial rating of the combined needle families.
Reviewed & verified by the MPN Base engineering desk against source catalog SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.10 needle roller / cylindrical-needle thrust on 2026-09-26. Read our editorial & correction policy.