NKXR20-Z bearing: complete specifications & equivalents
The NKXR20-Z 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 | 84 g |
| Manufacturer designation | NKXR 20 Z |
| 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 | SKF | full Dimensions and internal design equivalent — standard interchange. | Same 20×30×30 mm envelope and equivalent catalogue ratings; NKXR20 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-Z model number is decoded
For a 20 mm shaft under strong one-direction axial load with limited radial space, NKXR 20 Z from the combined needle roller / full complement needle thrust bearings stacks a caged needle radial part with a full complement thrust needle part: 20×30×30 mm. Reading the designation: NKXR marks needle roller + full complement needle thrust, the number the 20 mm shaft seat; 30 mm OD and 30 mm height follow the series plan. Execution notes: the Z suffix shields the thrust needle set; the full complement part delivers the highest axial rating in the family but needs the minimum axial load (factor A 0.00018) to prevent needle skidding. Speed ceilings differ by part: 3,800 r/min thermal reference and 7,500 r/min limiting — the thrust element governs, since its washer faces see sliding components of contact. These units run at low speed with high axial load: verify lubricant channeling at the washer faces after the first hour, as the packed thrust set pumps grease axially out of the 30 mm tall envelope.
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
- 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
- grease starvation at the roller ends when relubrication intervals are stretched in dirty duty
- hard-particle indentation in unfiltered lubricant
- 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.
- The quoted 16.5/25.5 kN ratings are SKF catalogue values for this exact execution (NKXR 20 Z); ratings can be revised without the order number changing, so keep the catalogue version (SKF catalogue PUB BU/P1 17000) with the drawing.
- Oscillating pivots fail differently: rocking through a small angle concentrates wear in the same roller positions — inspect those zones, and consider rotating the assembly's clock position at service intervals.
- 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 Z facing the working thrust.
- Minimum axial load is a real requirement: below factor A 0.00018 the thrust elements skid, polish their raceways and lose them — springs or preload washers belong in the arrangement drawing, not the troubleshooting notes.
- The 16.5/25.5 kN ratings and 84 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
Which dimensions does the NKXR 20 Z have?
A NKXR 20 Z 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 84 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.
What does NKXR 20 Z mean in SKF part numbering?
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.
Does the NKXR 20 Z need a hardened and ground shaft?
The radial needle part of the NKXR 20 Z runs directly on the 20 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.
What mounting mistakes ruin a NKXR 20 Z?
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.
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.