HK0908 bearing: complete specifications & equivalents
The HK0908 is a ISO 3245 radial bearing sized 9 x 13 x 8 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 9 mm |
| Outer diameter D | 13 mm |
| Width B | 8 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | none |
| Basic dynamic load rating C | 3.52 kN |
| Basic static load rating C0 | 3.9 kN |
| Fatigue load limit Pu | 0.415 kN |
| Reference speed (thermal) | 18000 rpm |
| Limiting speed (mechanical) | 20000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 3 g |
| Manufacturer designation | HK 0908 |
| Standard | ISO 3245 |
| Catalog version | SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.2 drawn cup needle roller bearings |
| Last verified | 2026-09-26 |
Source: catalog reference (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.2 drawn cup needle roller bearings) · extracted 2026-09-26
Parameters extracted from the official SKF Rolling Bearings catalogue (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.2 drawn cup needle roller bearings); 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 & HK-series range
| Bore d | 0.354 in |
|---|---|
| Outer diameter D | 0.512 in |
| Width B | 0.315 in |
| ISO bore code | 08 |
| Radial section height (D−d)/2 | 2 mm |
| Smallest bore in HK-series | 3 mm |
| Largest outer diameter in HK-series | 68 mm |
| Width range across HK-series | 6–38 mm |
| Bore position in HK-series (smallest first) | 7 of 26 |
| Bore above smallest HK-series size | 6 mm |
Cross references & equivalents
No verified interchange data yet. Send an inquiry and our team will confirm equivalents manually.
How the HK0908 model number is decoded
In SKF catalogue PUB BU/P1 17000, HK 0908 denotes a 9×13×8 mm drawn cup needle roller bearing with open ends — the shaft journal is the inner raceway, the pressed shell the outer, and the cage keeps the rollers parallel. SKF's HK numbering puts the shaft size first: 09 → Fw 9 mm (the ground, hardened journal), 08 → width 8 mm, with the 13 mm shell OD from the ISO 3245 dimension table. Open caged execution: the standard HK drawn cup with steel cage, relubricable through the shaft where the housing allows. Caged HK bearings space the rollers for lower friction than full complement HK types; the cage is not a seal — 2RS executions are the sealed members of the family. The 3 g catalogue mass and 2.0 mm radial section ((13−9)/2) frame a rating of about 0.39 kN dynamic per millimetre of bore — the needle construction's density advantage over ball bearings of the same envelope. The shell is intentionally thin: seat it square with a slow press stroke, support the housing wall behind the bore, and stop the moment the cup face meets the shoulder — hammer blows split drawn cups.
Typical equipment & failure modes
Common applications
- spindle clusters of drilling and tapping units
- auto steering gear rack supports
- clutch release mechanisms and cable pulleys
- office equipment and power tool gear trains
Known failure patterns
- raceway spalling once the catalogue L10 life is exceeded or after overload events
- drawn-cup shell distortion or splitting from a careless press-in without a seating mandrel
- abrasive paste formation from dust ingressing past open ends without effective housing seals
- false brinelling of standby equipment under external vibration
Selection pitfalls — read before you substitute
- On a 9 mm seat the housing bore quality dominates life: a bore 0.02 mm out of round pinches the 13 mm ring or cup into a lobed shape, and the rollers then trace the housing's geometry error, not the design load.
- 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.
- Contamination, not fatigue, kills most small needle bearings: with raceways this narrow, one hard particle dents a full-width line — seal the housing even when the bearing execution itself is open.
- The 3.52/3.9 kN ratings and 3 g mass are SKF catalogue values transcribed from ch. 7.2 of PUB BU/P1 17000 (PDF table page 620); combined-type axial ratings appear in the text above because the structured record carries radial values only.
Frequently asked questions
What limits the service life of a HK 0908?
Beyond the L10 rating, the practical limits are journal/raceway hardness for the 9 mm seat, lubricant condition at the roller ends, and contamination through open ends — the 2.0 mm radial section leaves no reserve once a raceway is dented or ribboned.
What are the dimensions and ratings of the HK 0908?
A HK 0908 measures 9 mm bore/Fw × 13 mm outside diameter × 8 mm width (0.354 × 0.512 × 0.315 in). From SKF catalogue PUB BU/P1 17000: radial dynamic rating C 3.52 kN, static C0 3.9 kN, fatigue limit Pu 0.415 kN, limiting speed 20,000 r/min, reference speed 18,000 r/min, mass about 3 g.
How is the HK 0908 designation read?
HK = open-end drawn cup needle roller bearing (ISO 3245); the first two digits give Fw 9 mm, the last two the width 8 mm, the shell OD 13 mm follows the plan. 2RS adds both-side contact seals, TN the polymer cage.
Can the HK 0908 run on an unhardened shaft?
No. In this execution the 9 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. 7.2 drawn cup needle roller bearings on 2026-09-26. Read our editorial & correction policy.