NX25-Z bearing: complete specifications & equivalents
The NX25-Z is a DIN 616 radial bearing sized 25 x 37 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 | 25 mm |
| Outer diameter D | 37 mm |
| Width B | 30 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | none |
| Basic dynamic load rating C | 15.1 kN |
| Basic static load rating C0 | 24.5 kN |
| Fatigue load limit Pu | 2.9 kN |
| Reference speed (thermal) | 5600 rpm |
| Limiting speed (mechanical) | 3800 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 120 g |
| Manufacturer designation | NX 25 Z |
| Standard | DIN 616 |
| Catalog version | SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.8 needle roller / thrust ball, full complement thrust part |
| Last verified | 2026-09-26 |
Source: catalog reference (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.8 needle roller / thrust ball, full complement 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. 7.8 needle roller / thrust ball, full complement 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 & NX-series range
| Bore d | 0.984 in |
|---|---|
| Outer diameter D | 1.457 in |
| Width B | 1.181 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 6 mm |
| Smallest bore in NX-series | 7 mm |
| Largest outer diameter in NX-series | 47 mm |
| Width range across NX-series | 18–30 mm |
| Bore position in NX-series (smallest first) | 7 of 9 |
| Bore above smallest NX-series size | 18 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| NX25 | SKF | full Dimensions and internal design equivalent — standard interchange. | Same 25×37×30 mm envelope and equivalent catalogue ratings; NX25 is the combined needle/thrust ball execution — boundary-dimension interchangeable, execution differences (seals, shields, cage) apply. |
| RNA6904 | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 25×37×30 mm envelope, but catalogue C/C0 differ between the executions (15.1/24.5 vs 35.2/53 kN) — boundary dimensions match, not a load-rating equivalent. |
| NKX25-Z | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 25×37×30 mm envelope, but catalogue C/C0 differ between the executions (15.1/24.5 vs 19/32.5 kN) — boundary dimensions match, not a load-rating equivalent. |
| NKX25 | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 25×37×30 mm envelope, but catalogue C/C0 differ between the executions (15.1/24.5 vs 19/32.5 kN) — boundary dimensions match, not a load-rating equivalent. |
| NKXR25 | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 25×37×30 mm envelope, but catalogue C/C0 differ between the executions (15.1/24.5 vs 19/32.5 kN) — boundary dimensions match, not a load-rating equivalent. |
| NKXR25-Z | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 25×37×30 mm envelope, but catalogue C/C0 differ between the executions (15.1/24.5 vs 19/32.5 kN) — boundary dimensions match, not a load-rating equivalent. |
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 NX25-Z model number is decoded
In SKF catalogue PUB BU/P1 17000, NX 25 Z denotes a combined bearing whose thrust part is filled with the maximum number of balls: highest axial capacity of the NX/NKX family at low-to-moderate speed, radial part 15.1 kN C. The number in NX 25 Z is the shaft diameter in millimetres; NX types differ from NKX only in the thrust part — full complement balls here, caged balls there — which changes axial capacity and speed ceiling. Full complement thrust parts run slower than caged ones: observe the 3,800 r/min limiting speed, and expect the thrust part to govern the thermal ceiling. The minimum load factor A 0.0042 applies to the thrust part: below that axial load the rolling elements of the thrust set skid, so springs or preload washers are part of the arrangement, not an afterthought. Mounting: assemble the thrust washer set with the keyed washer in the housing, fill the packed ball complement with grease so the balls adhere during fitting, and orient the thrust part toward the working axial load.
Typical equipment & failure modes
Common applications
- valve and dosing pump stems with slow axial push
- light rotary tables under axial load
- oscillating pivots with steady axial preload
- small hoisting and winch drums
Known failure patterns
- raceway spalling once the catalogue L10 life is exceeded or after overload events
- 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
- corrosion pitting from condensation in intermittently operated machinery
- thrust-part ball or roller skidding and smearing when the axial load falls below the minimum factor
Selection pitfalls — read before you substitute
- On a 25 mm seat the housing bore quality dominates life: a bore 0.02 mm out of round pinches the 37 mm ring or cup into a lobed shape, and the rollers then trace the housing's geometry error, not the design load.
- Hardness is load capacity: in families without an inner ring the 25 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 15.1/24.5 kN ratings are SKF catalogue values for this exact execution (NX 25 Z); ratings can be revised without the order number changing, so keep the catalogue version (SKF catalogue PUB BU/P1 17000) with the drawing.
- Height stack-up is easy to mis-check: the thrust-washer part adds height beyond a plain needle bearing, and clamping the stack solid over it preloads the thrust set beyond its rating.
- Do not treat the axial rating 12.4 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 15.1/24.5 kN ratings and 120 g mass are SKF catalogue values transcribed from ch. 7.8 of PUB BU/P1 17000 (PDF table page 656); combined-type axial ratings appear in the text above because the structured record carries radial values only.
Frequently asked questions
How should the NX 25 Z be mounted?
Press on the ring faces only with a fitting sleeve, keep everything square to the 25 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 NX 25 Z?
Beyond the L10 rating, the practical limits are journal/raceway hardness for the 25 mm seat, lubricant condition at the roller ends, and contamination through open ends — the 6.0 mm radial section leaves no reserve once a raceway is dented or ribboned.
What are the dimensions and ratings of the NX 25 Z?
A NX 25 Z measures 25 mm bore/Fw × 37 mm outside diameter × 30 mm width (0.984 × 1.457 × 1.181 in). From SKF catalogue PUB BU/P1 17000: radial dynamic rating C 15.1 kN, static C0 24.5 kN, fatigue limit Pu 2.9 kN, limiting speed 3,800 r/min, reference speed 5,600 r/min, mass about 120 g. Axial ratings of the thrust part: dynamic Ca 12.4 kN (Ca), static C0a 28.5 kN (C0a), minimum load factor A 0.0042; the thrust set carries load in one direction only.
How is the NX 25 Z designation read?
NX = needle roller radial part + full complement thrust ball part for a 25 mm shaft; the catalogue plan completes 37 mm OD and 30 mm overall height. The packed thrust set maximises axial capacity at low speed.
Reviewed & verified by the MPN Base engineering desk against source catalog SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.8 needle roller / thrust ball, full complement thrust part on 2026-09-26. Read our editorial & correction policy.