NA4840 bearing: complete specifications & equivalents
The NA4840 is a ISO 1206 radial bearing sized 200 x 250 x 50 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 200 mm |
| Outer diameter D | 250 mm |
| Width B | 50 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | none |
| Basic dynamic load rating C | 224 kN |
| Basic static load rating C0 | 735 kN |
| Fatigue load limit Pu | 75 kN |
| Reference speed (thermal) | 1800 rpm |
| Limiting speed (mechanical) | 2000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 5800 g |
| Manufacturer designation | NA 4840 |
| Standard | ISO 1206 |
| Catalog version | SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.4 machined rings with flanges, with an inner ring |
| Last verified | 2026-09-26 |
Source: catalog reference (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.4 machined rings with flanges, with an inner ring) · extracted 2026-09-26
Parameters extracted from the official SKF Rolling Bearings catalogue (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.4 machined rings with flanges, with an inner ring); 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 & NA-48-series range
| Bore d | 7.874 in |
|---|---|
| Outer diameter D | 9.843 in |
| Width B | 1.969 in |
| ISO bore code | 40 |
| Radial section height (D−d)/2 | 25 mm |
| Smallest bore in NA-48-series | 110 mm |
| Largest outer diameter in NA-48-series | 480 mm |
| Width range across NA-48-series | 30–100 mm |
| Bore position in NA-48-series (smallest first) | 10 of 19 |
| Bore above smallest NA-48-series size | 90 mm |
Cross references & equivalents
No verified interchange data yet. Send an inquiry and our team will confirm equivalents manually.
How the NA4840 model number is decoded
In SKF catalogue PUB BU/P1 17000, NA 4840 denotes a complete needle roller bearing for a 200 mm shaft — machined inner and outer rings, integral flanges on the outer ring retaining the roller set, 250 mm OD and 50 mm width. The designation NA 4840 tells you the envelope — 200×250×50 mm — and the family tells you the construction: complete bearing, replaceable inner ring, flanged outer ring retaining the needle rollers. Execution notes: the inner ring is ground on bore and raceway, so the shaft seat is a normal k5/j6; the flanged outer ring needs no housing shoulder, and NA 49 2RS executions add seals with a wider outer ring. Selection arithmetic: C 224 kN against C0 735 kN gives a C0/C ratio of 3.28, and the 75 kN fatigue load limit Pu sets the floor for the adjusted-life calculation at contaminated lubrication. Mounting: heat or press the inner ring onto the 200 mm k5 seat (max 120 °C), fit the flanged outer ring into the H7 housing bore, and check the 50 mm assembly for free rotation before applying load.
Typical equipment & failure modes
Common applications
- gearbox shafts where the journal cannot be hardened on site
- wheel and lever pivots needing a replaceable inner ring
- conveyor roller ends and return rollers
- agricultural implement pivots and cutter heads
Known failure patterns
- raceway spalling once the catalogue L10 life is exceeded or after overload events
- 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
- rolling-contact fatigue spalling after the rated L10 life
- inner-ring bore fretting on a loose shaft seat, migrating hard particles into the rolling contact
Selection pitfalls — read before you substitute
- Above 50 mm bore, thermal growth matters: the 200 mm inner ring or journal grows with temperature faster than the housing, and the small clearance of a needle roller contact leaves little reserve — check running clearance hot, not just at assembly.
- 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.
- 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.
- The 224/735 kN ratings and 5800 g mass are SKF catalogue values transcribed from ch. 7.4 of PUB BU/P1 17000 (PDF table page 646); combined-type axial ratings appear in the text above because the structured record carries radial values only.
Frequently asked questions
What limits the service life of a NA 4840?
Beyond the L10 rating, the practical limits are journal/raceway hardness for the 200 mm seat, lubricant condition at the roller ends, and contamination through open ends — the 25.0 mm radial section leaves no reserve once a raceway is dented or ribboned.
What are the dimensions and ratings of the NA 4840?
A NA 4840 measures 200 mm bore/Fw × 250 mm outside diameter × 50 mm width (7.874 × 9.843 × 1.969 in). From SKF catalogue PUB BU/P1 17000: radial dynamic rating C 224 kN, static C0 735 kN, fatigue limit Pu 75 kN, limiting speed 2,000 r/min, reference speed 1,800 r/min, mass about 5800 g.
How is the NA 4840 designation read?
The letters mark a machined-ring needle roller bearing with inner ring: 200 mm bore, 50 mm width, 250 mm OD per the series plan. The hardened inner ring is the raceway, so an ordinary k5 shaft seat suffices.
Can the NA 4840 run on an unhardened shaft?
Yes — that is the point of this family. The NA 4840 carries its own hardened, ground inner ring on a 200 mm seat, so the shaft needs only a normal k5/j6 finish. The inner ring is separable and replaceable.
Reviewed & verified by the MPN Base engineering desk against source catalog SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.4 machined rings with flanges, with an inner ring on 2026-09-26. Read our editorial & correction policy.