NA4844 bearing: complete specifications & equivalents
The NA4844 is a ISO 1206 radial bearing sized 220 x 270 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 | 220 mm |
| Outer diameter D | 270 mm |
| Width B | 50 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | none |
| Basic dynamic load rating C | 238 kN |
| Basic static load rating C0 | 815 kN |
| Fatigue load limit Pu | 81.5 kN |
| Reference speed (thermal) | 1700 rpm |
| Limiting speed (mechanical) | 1900 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 6350 g |
| Manufacturer designation | NA 4844 |
| 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 | 8.661 in |
|---|---|
| Outer diameter D | 10.63 in |
| Width B | 1.969 in |
| ISO bore code | 44 |
| 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) | 11 of 19 |
| Bore above smallest NA-48-series size | 110 mm |
Cross references & equivalents
No verified interchange data yet. Send an inquiry and our team will confirm equivalents manually.
How the NA4844 model number is decoded
NA 4844 is a machined-ring needle roller bearing with an inner ring: flanged outer ring plus a separate 220 mm bore inner ring, so the shaft seat needs only ordinary tolerance, as tabulated by SKF in SKF catalogue PUB BU/P1 17000. The designation NA 4844 tells you the envelope — 220×270×50 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 238 kN against C0 815 kN gives a C0/C ratio of 3.42, and the 81.5 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 220 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 220 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.
- Do not interchange envelope-identical needle families blindly: NA 4844 shares its 220×270×50 mm outline with inner-ring and sealed siblings whose ratings differ — the family letters are part of the specification, not decoration.
- Reference and limiting speeds are different limits: the 1,700 r/min reference is the thermal criterion under load, The limiting value is mechanical; the reference value is thermal under load, and grease choice moves it substantially.
- The 238/815 kN ratings and 6350 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 are the dimensions and ratings of the NA 4844?
A NA 4844 measures 220 mm bore/Fw × 270 mm outside diameter × 50 mm width (8.661 × 10.63 × 1.969 in). From SKF catalogue PUB BU/P1 17000: radial dynamic rating C 238 kN, static C0 815 kN, fatigue limit Pu 81.5 kN, limiting speed 1,900 r/min, reference speed 1,700 r/min, mass about 6350 g.
How is the NA 4844 designation read?
The letters mark a machined-ring needle roller bearing with inner ring: 220 mm bore, 50 mm width, 270 mm OD per the series plan. The hardened inner ring is the raceway, so an ordinary k5 shaft seat suffices.
Can the NA 4844 run on an unhardened shaft?
Yes — that is the point of this family. The NA 4844 carries its own hardened, ground inner ring on a 220 mm seat, so the shaft needs only a normal k5/j6 finish. The inner ring is separable and replaceable.
How should the NA 4844 be mounted?
Mount the inner ring on the 220 mm seat first (induction heat, max 120 °C, or press), then fit the flanged outer ring into the H7 housing bore. Verify free rotation and, for 2RS executions, check the wider outer ring against the housing depth.
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.