NKXR40-Z bearing: complete specifications & equivalents
The NKXR40-Z is a DIN 616 radial bearing sized 40 x 52 x 32 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 40 mm |
| Outer diameter D | 52 mm |
| Width B | 32 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | none |
| Basic dynamic load rating C | 26.4 kN |
| Basic static load rating C0 | 51 kN |
| Fatigue load limit Pu | 6.3 kN |
| Reference speed (thermal) | 2400 rpm |
| Limiting speed (mechanical) | 5000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 210 g |
| Manufacturer designation | NKXR 40 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 | 1.575 in |
|---|---|
| Outer diameter D | 2.047 in |
| Width B | 1.26 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 6 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) | 7 of 9 |
| Bore above smallest NKXR-series size | 25 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| NKXR40 | SKF | full Dimensions and internal design equivalent — standard interchange. | Same 40×52×32 mm envelope and equivalent catalogue ratings; NKXR40 is the combined needle/thrust needle execution — boundary-dimension interchangeable, execution differences (seals, shields, cage) apply. |
| NKX40-Z | SKF | full Dimensions and internal design equivalent — standard interchange. | Envelope-identical (40×52×32 mm) combined needle/thrust ball execution with ratings within 10 % — substitution possible after checking ring/flange construction. |
| NKX40 | SKF | full Dimensions and internal design equivalent — standard interchange. | Envelope-identical (40×52×32 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 NKXR40-Z model number is decoded
SKF lists NKXR 40 Z where axial capacity dominates: the packed thrust needle set carries 43 kN (Ca) dynamically at the cost of speed, while the caged radial rollers contribute 26.4 kN. In SKF nomenclature NKXR is the highest-capacity combined family: 40 mm shaft seat, packed thrust needles above the radial cage, axial rating 43 kN (Ca) dynamic. Thrust needle sets tolerate slow speeds and heavy loads: the 5,000 r/min limiting speed is far below ball-thrust equivalents, and lubricant film at the washer faces governs life. Selection arithmetic for the combined unit: radial C 26.4 kN, radial C0 51 kN, axial dynamic 43 kN (Ca) and axial static 137 kN (C0a); combine them with the equivalent-load factors from the catalogue before checking L10. 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 32 mm tall envelope.
Typical equipment & failure modes
Common applications
- extruder and mixer thrust positions
- large valve stems under high axial load
- turntables and slewing pivots with shock loads
- press-fit die set guide positions
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
- thrust-part ball or roller skidding and smearing when the axial load falls below the minimum factor
Selection pitfalls — read before you substitute
- At 40 mm bore, verify shaft deflection against the needle length: these rollers tolerate little edge loading, and a simply supported span between 40 mm seats can bend past the compensation range long before the load rating is exhausted.
- 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: NKXR 40 Z shares its 40×52×32 mm outline with inner-ring and sealed siblings whose ratings differ — the family letters are part of the specification, not decoration.
- 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 40 Z facing the working thrust.
- Minimum axial load is a real requirement: below factor A 0.0015 the thrust elements skid, polish their raceways and lose them — springs or preload washers belong in the arrangement drawing, not the troubleshooting notes.
- The 26.4/51 kN ratings and 210 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 40 Z have?
A NKXR 40 Z measures 40 mm bore/Fw × 52 mm outside diameter × 32 mm width (1.575 × 2.047 × 1.26 in). From SKF catalogue PUB BU/P1 17000: radial dynamic rating C 26.4 kN, static C0 51 kN, fatigue limit Pu 6.3 kN, limiting speed 5,000 r/min, reference speed 2,400 r/min, mass about 210 g. Axial ratings of the thrust part: dynamic Ca 43 kN (Ca), static C0a 137 kN (C0a), minimum load factor A 0.0015; the thrust set carries load in one direction only.
What does NKXR 40 Z mean in SKF part numbering?
NKXR = needle roller radial part + full complement needle thrust part for a 40 mm shaft: 52 mm OD, 32 mm overall height, the highest axial rating of the combined needle families.
Does the NKXR 40 Z need a hardened and ground shaft?
The radial needle part of the NKXR 40 Z runs directly on the 40 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 40 Z?
Press on the ring faces only with a fitting sleeve, keep everything square to the 40 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.