K42X50X20 bearing: complete specifications & equivalents
The K42X50X20 is a DIN 5402 radial bearing sized 42 x 50 x 20 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 42 mm |
| Outer diameter D | 50 mm |
| Width B | 20 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | none |
| Basic dynamic load rating C | 33.6 kN |
| Basic static load rating C0 | 57 kN |
| Fatigue load limit Pu | 7.1 kN |
| Reference speed (thermal) | 9500 rpm |
| Limiting speed (mechanical) | 11000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 53 g |
| Manufacturer designation | K 42x50x20 |
| 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 | 1.654 in |
|---|---|
| Outer diameter D | 1.969 in |
| Width B | 0.787 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 4 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) | 17 of 22 |
| Bore above smallest K-series size | 39 mm |
Cross references & equivalents
No verified interchange data yet. Send an inquiry and our team will confirm equivalents manually.
How the K42X50X20 model number is decoded
SKF catalogue number K 42x50x20 denotes a needle roller and cage assembly for a 42 mm shaft seat — the cage spaces the rollers, the machine parts provide both raceways, and the 20 mm width is all the radial room it needs. Reading the designation: K marks the needle roller and cage assembly, the three numbers give Fw 42 (shaft journal), E 50 (assembly outside diameter) and B 20 (width) in millimetres — the machine parts complete the bearing. 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. Catalogue mass 53 g at 42×50×20 mm makes this one of the highest capacity-per-gram choices in the needle roller and cage assemblies; the limit is usually the shaft's ability to serve as a raceway, not the rolling contact itself. Mounting: grind the 42 mm journal to the catalogue raceway tolerance after hardening to 58–64 HRC, bore the housing to E 50 mm H6, and slide the assembly in axially — pressing through the cage distorts it and locks the rollers.
Typical equipment & failure modes
Common applications
- planetary gear pins in compact transmissions
- connecting rods of small compressors where radial height is critical
- rocker arm and rocker pin pivots on camshafts
- pump and gearbox idler gears running on hardened pins
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
- 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 42 mm bore, verify shaft deflection against the needle length: these rollers tolerate little edge loading, and a simply supported span between 42 mm seats can bend past the compensation range long before the load rating is exhausted.
- 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.
- Do not interchange envelope-identical needle families blindly: K 42x50x20 shares its 42×50×20 mm outline with inner-ring and sealed siblings whose ratings differ — the family letters are part of the specification, not decoration.
- The 33.6/57 kN ratings and 53 g mass are SKF catalogue values transcribed from ch. 7.1 of PUB BU/P1 17000 (PDF table page 618); combined-type axial ratings appear in the text above because the structured record carries radial values only.
Frequently asked questions
What mounting mistakes ruin a K 42x50x20?
Slide the assembly over the ground 42 mm journal with a mounting sleeve, bore the housing to E 50 mm, and retain with a washer spanning the cage. Never press against the cage or rotate before the bearing is lubricated and loaded.
Is the K 42x50x20 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 K 42x50x20 have?
A K 42x50x20 measures 42 mm bore/Fw × 50 mm outside diameter × 20 mm width (1.654 × 1.969 × 0.787 in). From SKF catalogue PUB BU/P1 17000: radial dynamic rating C 33.6 kN, static C0 57 kN, fatigue limit Pu 7.1 kN, limiting speed 11,000 r/min, reference speed 9,500 r/min, mass about 53 g.
What does K 42x50x20 mean in SKF part numbering?
K = needle roller and cage assembly (DIN 5402); the three figures give Fw 42 mm (shaft journal), E 50 mm (complement outside diameter, matched by the housing bore) and B 20 mm width. TN marks the glass fibre reinforced PA66 cage.
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.