RNA4912 bearing: complete specifications & equivalents
The RNA4912 is a ISO 1206 radial bearing sized 68 x 85 x 25 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 68 mm |
| Outer diameter D | 85 mm |
| Width B | 25 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | none |
| Basic dynamic load rating C | 60.5 kN |
| Basic static load rating C0 | 114 kN |
| Fatigue load limit Pu | 14.3 kN |
| Reference speed (thermal) | 6000 rpm |
| Limiting speed (mechanical) | 6700 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 280 g |
| Manufacturer designation | RNA 4912 |
| Standard | ISO 1206 |
| Catalog version | SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.3 machined rings with flanges, without an inner ring |
| Last verified | 2026-09-26 |
Source: catalog reference (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.3 machined rings with flanges, without 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. 7.3 machined rings with flanges, without 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 & RNA-49-series range
| Bore d | 2.677 in |
|---|---|
| Outer diameter D | 3.346 in |
| Width B | 0.984 in |
| ISO bore code | 12 |
| Radial section height (D−d)/2 | 8.5 mm |
| Smallest bore in RNA-49-series | 14 mm |
| Largest outer diameter in RNA-49-series | 190 mm |
| Width range across RNA-49-series | 13–50 mm |
| Bore position in RNA-49-series (smallest first) | 16 of 28 |
| Bore above smallest RNA-49-series size | 54 mm |
Cross references & equivalents
No verified interchange data yet. Send an inquiry and our team will confirm equivalents manually.
How the RNA4912 model number is decoded
RNA 4912 is a ribbed machined-ring needle roller bearing (no inner ring) sized 68×85×25 mm: the ground outside diameter seats in the housing, the integral flanges hold the rollers, and the 68 mm shaft journal completes the bearing. Reading the designation: RNA gives the series and the numbers the boundary plan — 68 mm Fw for the shaft seat, 25 mm width; the 85 mm OD comes from the dimension series, and the absence of an inner ring is built into the family name. The machined ring is through-hardened and ground on OD, bore-side raceway and faces; the flanged lip design means the housing shoulder can be omitted — the ring clamps axially between housing wall and cover washer. Catalogue mass 280 g at 68×85×25 mm makes this one of the highest capacity-per-gram choices in the dimension series 49 needle roller bearings without inner ring; the limit is usually the shaft's ability to serve as a raceway, not the rolling contact itself. Grease through the housing groove before fitting the shaft; the integral flanges hold the grease film at the roller ends, which is where these bearings first starve.
Typical equipment & failure modes
Common applications
- cam followers built up from separate components
- crank pins and eccentrics where the hardened journal is the raceway
- gearbox planetary and idler gears on hardened pins
- piston-pin style pivots in hydraulic pumps
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
- smearing of rollers and journal during idle periods because the radial section holds too little lubricant
Selection pitfalls — read before you substitute
- Above 50 mm bore, thermal growth matters: the 68 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 6,000 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 68 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 60.5/114 kN ratings and 280 g mass are SKF catalogue values transcribed from ch. 7.3 of PUB BU/P1 17000 (PDF table page 632); combined-type axial ratings appear in the text above because the structured record carries radial values only.
Frequently asked questions
Is the RNA 4912 sealed?
No — this execution is open and depends on the housing sealing arrangement; grease it at assembly and keep the relubrication interval short in dirty duty.
Which dimensions does the RNA 4912 have?
A RNA 4912 measures 68 mm bore/Fw × 85 mm outside diameter × 25 mm width (2.677 × 3.346 × 0.984 in). From SKF catalogue PUB BU/P1 17000: radial dynamic rating C 60.5 kN, static C0 114 kN, fatigue limit Pu 14.3 kN, limiting speed 6,700 r/min, reference speed 6,000 r/min, mass about 280 g.
What does RNA 4912 mean in SKF part numbering?
RNA names a machined-ring needle roller bearing without inner ring: the figures give Fw 68 mm and width 25 mm, OD 85 mm comes from the dimension series, and the flanged outer ring retains the caged rollers.
Does the RNA 4912 need a hardened and ground shaft?
No. In this execution the 68 mm shaft journal is the inner raceway: it must be ground and hardened to 58–64 HRC (with matching housing bore quality on the outside). If the shaft cannot meet that, order the inner-ring sibling (NKI/NA execution) plus its ground inner ring instead.
Reviewed & verified by the MPN Base engineering desk against source catalog SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.3 machined rings with flanges, without an inner ring on 2026-09-26. Read our editorial & correction policy.