NA6905 bearing: complete specifications & equivalents
The NA6905 is a ISO 1206 radial bearing sized 25 x 42 x 30 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 25 mm |
| Outer diameter D | 42 mm |
| Width B | 30 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | none |
| Basic dynamic load rating C | 38 kN |
| Basic static load rating C0 | 62 kN |
| Fatigue load limit Pu | 7.65 kN |
| Reference speed (thermal) | 13000 rpm |
| Limiting speed (mechanical) | 15000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 160 g |
| Manufacturer designation | NA 6905 |
| 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 | 0.984 in |
|---|---|
| Outer diameter D | 1.654 in |
| Width B | 1.181 in |
| ISO bore code | 05 |
| Radial section height (D−d)/2 | 8.5 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) | 6 of 22 |
| Bore above smallest NA-69-series size | 13 mm |
Cross references & equivalents
No verified interchange data yet. Send an inquiry and our team will confirm equivalents manually.
How the NA6905 model number is decoded
NA 6905 provides the full machined-ring needle roller construction: ground inner ring on a 25 mm seat, flanged outer ring at 42 mm, caged needles between them — the standard choice when a replaceable inner raceway is required. In SKF nomenclature the leading letters mark a machined-ring needle bearing with inner ring: figures state 25 mm d and 30 mm B, the 42 mm outside diameter from the dimension series 69 needle roller bearings with inner ring, and the 2RS suffix would add contact seals. 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. Because the inner ring is separable, mount it first against its shoulder, then slide the outer ring and roller set over it — the order avoids forcing rollers across the shaft threads or burrs.
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
- needle edge loading and raceway denting when the shaft deflects beyond the compensation range
- polymer cage deformation when the local temperature exceeds the 120 °C sustained limit
- grease starvation at the roller ends when relubrication intervals are stretched in dirty duty
- brinelling of raceways from impact or pressing force transmitted through the rolling elements
- inner-ring raceway spalling after the narrow ring section runs hot with excessive interference
Selection pitfalls — read before you substitute
- On a 25 mm seat the housing bore quality dominates life: a bore 0.02 mm out of round pinches the 42 mm ring or cup into a lobed shape, and the rollers then trace the housing's geometry error, not the design load.
- The quoted 38/62 kN ratings are SKF catalogue values for this exact execution (NA 6905); 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.
- The 38/62 kN ratings and 160 g mass are SKF catalogue values transcribed from ch. 7.4 of PUB BU/P1 17000 (PDF table page 640); combined-type axial ratings appear in the text above because the structured record carries radial values only.
Frequently asked questions
What does NA 6905 mean in SKF part numbering?
The letters mark a machined-ring needle roller bearing with inner ring: 25 mm bore, 30 mm width, 42 mm OD per the series plan. The hardened inner ring is the raceway, so an ordinary k5 shaft seat suffices.
Does the NA 6905 need a hardened and ground shaft?
Yes — that is the point of this family. The NA 6905 carries its own hardened, ground inner ring on a 25 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 6905?
Mount the inner ring on the 25 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.
Is the NA 6905 sealed?
No — the open execution relies on housing seals; 2RS executions of the 49 series add contact seals with a wider outer ring as a separate order number.
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.