NK50-35-TN bearing: complete specifications & equivalents
The NK50-35-TN is a DIN 616 radial bearing sized 50 x 62 x 35 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 50 mm |
| Outer diameter D | 62 mm |
| Width B | 35 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | polymer (PA66 glass-fibre reinforced) |
| Basic dynamic load rating C | 58.3 kN |
| Basic static load rating C0 | 137 kN |
| Fatigue load limit Pu | 17 kN |
| Reference speed (thermal) | 8000 rpm |
| Limiting speed (mechanical) | 9000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 210 g |
| Manufacturer designation | NK 50/35 TN |
| Standard | DIN 616 |
| 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 & NK-series range
| Bore d | 1.969 in |
|---|---|
| Outer diameter D | 2.441 in |
| Width B | 1.378 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 6 mm |
| Smallest bore in NK-series | 5 mm |
| Largest outer diameter in NK-series | 130 mm |
| Width range across NK-series | 10–40 mm |
| Bore position in NK-series (smallest first) | 32 of 46 |
| Bore above smallest NK-series size | 45 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| NKX50-Z | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 50×62×35 mm envelope, but catalogue C/C0 differ between the executions (58.3/137 vs 38/78 kN) — boundary dimensions match, not a load-rating equivalent. |
| NKX50 | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 50×62×35 mm envelope, but catalogue C/C0 differ between the executions (58.3/137 vs 38/78 kN) — boundary dimensions match, not a load-rating equivalent. |
| NKXR50 | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 50×62×35 mm envelope, but catalogue C/C0 differ between the executions (58.3/137 vs 38/78 kN) — boundary dimensions match, not a load-rating equivalent. |
| NKXR50-Z | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 50×62×35 mm envelope, but catalogue C/C0 differ between the executions (58.3/137 vs 38/78 kN) — boundary dimensions match, not a load-rating equivalent. |
Interchange levels: full standard interchange · partial verify parameters · verify manual confirmation required. Links resolve to the equivalent model's specification page where available.
How the NK50-35-TN model number is decoded
NK 50/35 TN is a machined-ring needle roller bearing without an inner ring: a solid outer ring with integral flanges guiding the caged rollers, riding directly on a 50 mm hardened shaft journal, as listed in SKF catalogue PUB BU/P1 17000. The letters identify a flanged machined outer ring without inner ring; the figures give 50 mm Fw and 35 mm B — dimensionally identical envelopes exist with an inner ring under the NA/NKI names, which changes the shaft seat entirely. 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. Speed planning separates the two ceilings: 8,000 r/min thermal reference and 9,000 r/min mechanical limiting — needle bearings tolerate high rpm only with adequate lubricant film at the 50 mm seat. 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
- gearbox planetary and idler gears on hardened pins
- piston-pin style pivots in hydraulic pumps
- guide rollers running on hardened tracks
- swing arms and lever pivots with oscillating duty
Known failure patterns
- raceway spalling once the catalogue L10 life is exceeded or after overload events
- polymer cage deformation when the local temperature exceeds the 120 °C sustained limit
- abrasive paste formation from dust ingressing past open ends without effective housing seals
- hard-particle indentation in unfiltered lubricant
- rapid raceway scoring when the shaft journal hardness drops below 58 HRC or the ground finish wears away
Selection pitfalls — read before you substitute
- At 50 mm bore, verify shaft deflection against the needle length: these rollers tolerate little edge loading, and a simply supported span between 50 mm seats can bend past the compensation range long before the load rating is exhausted.
- Hardness is load capacity: in families without an inner ring the 50 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 58.3/137 kN ratings are SKF catalogue values for this exact execution (NK 50/35 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 58.3/137 kN ratings and 210 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
How is the NK 50/35 TN designation read?
NK names a machined-ring needle roller bearing without inner ring: the figures give Fw 50 mm and width 35 mm, OD 62 mm comes from the dimension series, and the flanged outer ring retains the caged rollers.
Can the NK 50/35 TN run on an unhardened shaft?
No. In this execution the 50 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 NK 50/35 TN be mounted?
Press on the ring faces only with a fitting sleeve, keep everything square to the 50 mm seat, and never transmit force through the rolling elements. Follow the catalogue's seat tolerances — the narrow needle contact forgives neither tilt nor burrs.
What limits the service life of a NK 50/35 TN?
Beyond the L10 rating, the practical limits are journal/raceway hardness for the 50 mm seat, lubricant condition at the roller ends, and contamination through open ends — the 6.0 mm radial section leaves no reserve once a raceway is dented or ribboned.
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.