K5X8X8-TN bearing: complete specifications & equivalents
The K5X8X8-TN is a DIN 5402 radial bearing sized 5 x 8 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 | 5 mm |
| Outer diameter D | 8 mm |
| Width B | 8 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | polymer (PA66 glass-fibre reinforced) |
| Basic dynamic load rating C | 2.29 kN |
| Basic static load rating C0 | 2 kN |
| Fatigue load limit Pu | 0.212 kN |
| Reference speed (thermal) | 36000 rpm |
| Limiting speed (mechanical) | 40000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 0.7 g |
| Manufacturer designation | K 5x8x8 TN |
| Standard | DIN 5402 |
| Catalog version | SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.1 needle roller and cage assemblies |
| Last verified | 2026-09-26 |
Source: catalog reference (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.1 needle roller and cage assemblies) · extracted 2026-09-26
Parameters extracted from the official SKF Rolling Bearings catalogue (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.1 needle roller and cage assemblies); 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 & K-series range
| Bore d | 0.197 in |
|---|---|
| Outer diameter D | 0.315 in |
| Width B | 0.315 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 1.5 mm |
| Smallest bore in K-series | 3 mm |
| Largest outer diameter in K-series | 63 mm |
| Width range across K-series | 7–32 mm |
| Bore position in K-series (smallest first) | 3 of 22 |
| Bore above smallest K-series size | 2 mm |
Cross references & equivalents
No verified interchange data yet. Send an inquiry and our team will confirm equivalents manually.
How the K5X8X8-TN model number is decoded
SKF lists K 5x8x8 TN in the K series of needle roller and cage assemblies: needle rollers caged at 5×8×8 mm, designed to run directly on a ground, hardened shaft and inside a machined housing bore. The designation numbers of K 5x8x8 TN state the three machine-seat dimensions — 5 mm journal, 8 mm bore-side complement diameter, 8 mm width — which is why ordering errors here show up as a sloppy or seized fit, not as a returned box. Because there are no rings, execution differences live in the cage: TN polymer cages reduce friction and noise, while the basic steel cage tolerates higher operating temperatures up to the lubricant limit. The 0.7 g catalogue mass and 1.5 mm radial section ((8−5)/2) frame a rating of about 0.46 kN dynamic per millimetre of bore — the needle construction's density advantage over ball bearings of the same envelope. Mounting: grind the 5 mm journal to the catalogue raceway tolerance after hardening to 58–64 HRC, bore the housing to E 8 mm H6, and slide the assembly in axially — pressing through the cage distorts it and locks the rollers.
Typical equipment & failure modes
Common applications
- pump and gearbox idler gears running on hardened pins
- hinge and pivot joints in printing and textile machinery
- universal joint crosses on commercial vehicles
- planetary gear pins in compact transmissions
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
- abrasive paste formation from dust ingressing past open ends without effective housing seals
- rolling-contact fatigue spalling after the rated L10 life
- smearing of rollers and journal during idle periods because the radial section holds too little lubricant
Selection pitfalls — read before you substitute
- At Fw 5 mm the rolling elements are under two millimetres long — handle the K 5x8x8 TN like a watch part: one dropped assembly, one over-pressed cup or one coarse journal finish outweighs any catalogue rating difference.
- Hardness is load capacity: in families without an inner ring the 5 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 2.29/2 kN ratings are SKF catalogue values for this exact execution (K 5x8x8 TN); ratings can be revised without the order number changing, so keep the catalogue version (SKF catalogue PUB BU/P1 17000) with the drawing.
- The 2.29/2 kN ratings and 0.7 g mass are SKF catalogue values transcribed from ch. 7.1 of PUB BU/P1 17000 (PDF table page 616); combined-type axial ratings appear in the text above because the structured record carries radial values only.
Frequently asked questions
What are the dimensions and ratings of the K 5x8x8 TN?
A K 5x8x8 TN measures 5 mm bore/Fw × 8 mm outside diameter × 8 mm width (0.197 × 0.315 × 0.315 in). From SKF catalogue PUB BU/P1 17000: radial dynamic rating C 2.29 kN, static C0 2 kN, fatigue limit Pu 0.212 kN, limiting speed 40,000 r/min, reference speed 36,000 r/min, mass about 0.7 g.
How is the K 5x8x8 TN designation read?
K = needle roller and cage assembly (DIN 5402); the three figures give Fw 5 mm (shaft journal), E 8 mm (complement outside diameter, matched by the housing bore) and B 8 mm width. TN marks the glass fibre reinforced PA66 cage.
Can the K 5x8x8 TN run on an unhardened shaft?
No. In this execution the 5 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.
How should the K 5x8x8 TN be mounted?
Slide the assembly over the ground 5 mm journal with a mounting sleeve, bore the housing to E 8 mm, and retain with a washer spanning the cage. Never press against the cage or rotate before the bearing is lubricated and loaded.
Reviewed & verified by the MPN Base engineering desk against source catalog SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.1 needle roller and cage assemblies on 2026-09-26. Read our editorial & correction policy.