NA4920 bearing: complete specifications & equivalents
The NA4920 is a ISO 1206 radial bearing sized 100 x 140 x 40 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 100 mm |
| Outer diameter D | 140 mm |
| Width B | 40 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | none |
| Basic dynamic load rating C | 125 kN |
| Basic static load rating C0 | 280 kN |
| Fatigue load limit Pu | 34 kN |
| Reference speed (thermal) | 3400 rpm |
| Limiting speed (mechanical) | 4000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 1900 g |
| Manufacturer designation | NA 4920 |
| 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-49-series range
| Bore d | 3.937 in |
|---|---|
| Outer diameter D | 5.512 in |
| Width B | 1.575 in |
| ISO bore code | 20 |
| Radial section height (D−d)/2 | 20 mm |
| Smallest bore in NA-49-series | 10 mm |
| Largest outer diameter in NA-49-series | 190 mm |
| Width range across NA-49-series | 13–50 mm |
| Bore position in NA-49-series (smallest first) | 24 of 28 |
| Bore above smallest NA-49-series size | 90 mm |
Cross references & equivalents
No verified interchange data yet. Send an inquiry and our team will confirm equivalents manually.
How the NA4920 model number is decoded
For a 100 mm shaft that cannot be hardened on site, NA 4920 adds a hardened, ground inner ring to the machined needle roller design: envelope 100×140×40 mm per the dimension series 49 needle roller bearings with inner ring plan. In SKF nomenclature the leading letters mark a machined-ring needle bearing with inner ring: figures state 100 mm d and 40 mm B, the 140 mm outside diameter from the dimension series 49 needle roller bearings with inner ring, and the 2RS suffix would add contact seals. TN polymer cage executions run quieter and tolerate grease-lubricated pivot duty; steel cage executions remain the choice for higher temperature or oil-bath lubrication. Catalogue mass 1900 g at 100×140×40 mm makes this one of the highest capacity-per-gram choices in the dimension series 49 needle roller bearings with inner ring; the limit is usually the shaft's ability to serve as a raceway, not the rolling contact itself. For NA 49 2RS executions the wider outer ring changes the housing depth: verify the 40 mm width and s offset dimensions against the open execution before reusing an existing bore.
Typical equipment & failure modes
Common applications
- printing and paper-handling rollers
- 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
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
- abrasive paste formation from dust ingressing past open ends without effective housing seals
- electrical erosion on VFD-driven shafts without brush or insulated mounting
- inner-ring raceway spalling after the narrow ring section runs hot with excessive interference
Selection pitfalls — read before you substitute
- Above 50 mm bore, thermal growth matters: the 100 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.
- Reference and limiting speeds are different limits: the 3,400 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.
- Hardness is load capacity: in families without an inner ring the 100 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 125/280 kN ratings and 1900 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
Which dimensions does the NA 4920 have?
A NA 4920 measures 100 mm bore/Fw × 140 mm outside diameter × 40 mm width (3.937 × 5.512 × 1.575 in). From SKF catalogue PUB BU/P1 17000: radial dynamic rating C 125 kN, static C0 280 kN, fatigue limit Pu 34 kN, limiting speed 4,000 r/min, reference speed 3,400 r/min, mass about 1900 g.
What does NA 4920 mean in SKF part numbering?
The letters mark a machined-ring needle roller bearing with inner ring: 100 mm bore, 40 mm width, 140 mm OD per the series plan. The hardened inner ring is the raceway, so an ordinary k5 shaft seat suffices.
Does the NA 4920 need a hardened and ground shaft?
Yes — that is the point of this family. The NA 4920 carries its own hardened, ground inner ring on a 100 mm seat, so the shaft needs only a normal k5/j6 finish. The inner ring is separable and replaceable.
What mounting mistakes ruin a NA 4920?
Mount the inner ring on the 100 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.