NKX45 bearing: complete specifications & equivalents
The NKX45 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) | 6300 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 250 g |
| Manufacturer designation | NKX 45 |
| 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-Z | SKF | full Dimensions and internal design equivalent — standard interchange. | Same 45×58×32 mm envelope and equivalent catalogue ratings; NKX45-Z 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 model number is decoded
SKF supplies NKX 45 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. In SKF nomenclature NKX is the combined family: the number states 45 mm, and unlike NX the thrust balls are caged, trading some axial capacity for speed and friction. 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. Axial capability is one-direction: size the arrangement so working thrust pushes the thrust-washer face, and provide a mirrored unit or separate bearing for load reversals. 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); 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 facing the working thrust.
- The 27.5/57 kN ratings and 250 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
Does the NKX 45 need a hardened and ground shaft?
The radial needle part of the NKX 45 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.
What mounting mistakes ruin a NKX 45?
Press on the ring faces only with a fitting sleeve, keep everything square to the 45 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.
Is the NKX 45 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 have?
A NKX 45 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 6,300 r/min, reference speed 4,500 r/min, mass about 250 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.
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.