NKX45-Z bearing: complete specifications & equivalents
The NKX45-Z is a DIN 616 radial bearing sized 45 x 58 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 | 45 mm |
| Outer diameter D | 58 mm |
| Width B | 32 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | none |
| Basic dynamic load rating C | 27.5 kN |
| Basic static load rating C0 | 57 kN |
| Fatigue load limit Pu | 7.1 kN |
| Reference speed (thermal) | 4500 rpm |
| Limiting speed (mechanical) | 3800 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 270 g |
| Manufacturer designation | NKX 45 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 | 1.772 in |
|---|---|
| Outer diameter D | 2.283 in |
| Width B | 1.26 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 6.5 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) | 10 of 13 |
| Bore above smallest NKX-series size | 35 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| NKX45 | SKF | full Dimensions and internal design equivalent — standard interchange. | Same 45×58×32 mm envelope and equivalent catalogue ratings; NKX45 is the combined needle/thrust ball execution — boundary-dimension interchangeable, execution differences (seals, shields, cage) apply. |
| NKXR45 | SKF | full Dimensions and internal design equivalent — standard interchange. | Envelope-identical (45×58×32 mm) combined needle/thrust needle execution with ratings within 10 % — substitution possible after checking ring/flange construction. |
| NKXR45-Z | SKF | full Dimensions and internal design equivalent — standard interchange. | Envelope-identical (45×58×32 mm) combined needle/thrust needle 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 NKX45-Z model number is decoded
SKF supplies NKX 45 Z for combined-load positions at moderate speed: the caged thrust balls reduce friction and allow 4,500 r/min reference where a full complement NX would overheat. Reading the designation: NKX marks needle roller + caged thrust ball, the number the 45 mm shaft seat; the 58 mm OD and 32 mm overall height come from the series plan. 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. The minimum load factor A 0.029 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. The caged thrust part survives moderate speed only with the Z shield intact — damaged shields admit grit straight into the ball raceways, and the narrow section leaves no margin.
Typical equipment & failure modes
Common applications
- turntable and swivel mounts
- machine tool feed spindles with one-direction thrust
- pump impeller shafts with steady axial pull
- gear pairs generating one-direction axial force
Known failure patterns
- needle edge loading and raceway denting when the shaft deflects beyond the compensation range
- 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
- false brinelling of standby equipment under external vibration
- thrust-part ball or roller skidding and smearing when the axial load falls below the minimum factor
Selection pitfalls — read before you substitute
- At 45 mm bore, verify shaft deflection against the needle length: these rollers tolerate little edge loading, and a simply supported span between 45 mm seats can bend past the compensation range long before the load rating is exhausted.
- The quoted 27.5/57 kN ratings are SKF catalogue values for this exact execution (NKX 45 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.
- Do not treat the axial rating 28.1 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 45 Z facing the working thrust.
- The 27.5/57 kN ratings and 270 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
Is the NKX 45 Z sealed?
No — this execution is open and depends on the housing sealing arrangement; grease it at assembly and keep the relubrication interval short in dirty duty.
Which dimensions does the NKX 45 Z have?
A NKX 45 Z measures 45 mm bore/Fw × 58 mm outside diameter × 32 mm width (1.772 × 2.283 × 1.26 in). From SKF catalogue PUB BU/P1 17000: radial dynamic rating C 27.5 kN, static C0 57 kN, fatigue limit Pu 7.1 kN, limiting speed 3,800 r/min, reference speed 4,500 r/min, mass about 270 g. Axial ratings of the thrust part: dynamic Ca 28.1 kN (Ca), static C0a 75 kN (C0a), minimum load factor A 0.029; the thrust set carries load in one direction only.
What does NKX 45 Z mean in SKF part numbering?
NKX = needle roller radial part + caged thrust ball part for a 45 mm shaft: 58 mm OD, 32 mm overall height. The caged thrust part trades some axial capacity for higher permissible speed versus NX.
Does the NKX 45 Z need a hardened and ground shaft?
The radial needle part of the NKX 45 Z runs directly on the 45 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.
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.