NA6911 bearing: complete specifications & equivalents
The NA6911 is a ISO 1206 radial bearing sized 55 x 80 x 45 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 55 mm |
| Outer diameter D | 80 mm |
| Width B | 45 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | none |
| Basic dynamic load rating C | 89.7 kN |
| Basic static load rating C0 | 190 kN |
| Fatigue load limit Pu | 23.2 kN |
| Reference speed (thermal) | 6300 rpm |
| Limiting speed (mechanical) | 7000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 780 g |
| Manufacturer designation | NA 6911 |
| 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-69-series range
| Bore d | 2.165 in |
|---|---|
| Outer diameter D | 3.15 in |
| Width B | 1.772 in |
| ISO bore code | 11 |
| Radial section height (D−d)/2 | 12.5 mm |
| Smallest bore in NA-69-series | 12 mm |
| Largest outer diameter in NA-69-series | 130 mm |
| Width range across NA-69-series | 22–63 mm |
| Bore position in NA-69-series (smallest first) | 14 of 22 |
| Bore above smallest NA-69-series size | 43 mm |
Cross references & equivalents
No verified interchange data yet. Send an inquiry and our team will confirm equivalents manually.
How the NA6911 model number is decoded
In SKF catalogue PUB BU/P1 17000, NA 6911 denotes a complete needle roller bearing for a 55 mm shaft — machined inner and outer rings, integral flanges on the outer ring retaining the roller set, 80 mm OD and 45 mm width. The designation NA 6911 tells you the envelope — 55×80×45 mm — and the family tells you the construction: complete bearing, replaceable inner ring, flanged outer ring retaining the needle rollers. Inner rings are separable: order replacement inner rings separately by d×D×B, since the outer ring and roller assembly survive journals that ruin an inner raceway. Minimum load matters: below roughly 0.02·C the rollers skid and smear; preloading the pivot or specifying a heavier execution avoids the glazing that pure oscillation produces on these raceways. Mounting: heat or press the inner ring onto the 55 mm k5 seat (max 120 °C), fit the flanged outer ring into the H7 housing bore, and check the 45 mm assembly for free rotation before applying load.
Typical equipment & failure modes
Common applications
- electric motor armature shafts with ground seats
- printing and paper-handling rollers
- gearbox shafts where the journal cannot be hardened on site
- wheel and lever pivots needing a replaceable inner ring
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 55 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.
- Hardness is load capacity: in families without an inner ring the 55 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 quoted 89.7/190 kN ratings are SKF catalogue values for this exact execution (NA 6911); ratings can be revised without the order number changing, so keep the catalogue version (SKF catalogue PUB BU/P1 17000) with the drawing.
- The 89.7/190 kN ratings and 780 g mass are SKF catalogue values transcribed from ch. 7.4 of PUB BU/P1 17000 (PDF table page 642); combined-type axial ratings appear in the text above because the structured record carries radial values only.
Frequently asked questions
Can the NA 6911 run on an unhardened shaft?
Yes — that is the point of this family. The NA 6911 carries its own hardened, ground inner ring on a 55 mm seat, so the shaft needs only a normal k5/j6 finish. The inner ring is separable and replaceable.
How should the NA 6911 be mounted?
Mount the inner ring on the 55 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.
What limits the service life of a NA 6911?
Beyond the L10 rating, the practical limits are journal/raceway hardness for the 55 mm seat, lubricant condition at the roller ends, and contamination through open ends — the 12.5 mm radial section leaves no reserve once a raceway is dented or ribboned.
What are the dimensions and ratings of the NA 6911?
A NA 6911 measures 55 mm bore/Fw × 80 mm outside diameter × 45 mm width (2.165 × 3.15 × 1.772 in). From SKF catalogue PUB BU/P1 17000: radial dynamic rating C 89.7 kN, static C0 190 kN, fatigue limit Pu 23.2 kN, limiting speed 7,000 r/min, reference speed 6,300 r/min, mass about 780 g.
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.