Description
Batch-Traceable Sourcing — Every INA NKI50/35-XL needle roller bearing we ship carries full distributor-channel documentation, so gearbox builders can trace the exact production lot back to the manufacturer’s quality records.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | INA NKI50/35-XL |
| Bearing Type | Needle Roller Bearing |
| Bore Diameter (Fw) | 50 mm |
| Outside Diameter (D) | 68 mm |
| Width (B) | 35 mm |
| Weight | 0.38 kg |
| Cage Material | Bearing Steel |
| Seal or Shield Type | Open |
| Load Direction | Radial |
| Style | Without Outer Ring, Without Inner Ring |
| Origin | Germany |
The XL suffix on this designation refers to INA’s X-Life series; specific internal geometry enhancements should be confirmed against the current manufacturer catalog for your exact production batch.
Application Suitability
| Industry | Typical Applications |
|---|---|
| Industrial Machinery | Medium-duty gearbox intermediate shafts |
| Automotive | Transmission countershaft needle stages |
| Material Handling | Conveyor drive reducer needle pockets |
What Happens When the X-Life Geometry Gets Ignored on the INA NKI50/35-XL
A standard-profile needle swapped in place of an X-Life roller will develop edge stress cracks before the first scheduled oil change.
I once stood in a Dubai gearbox rebuild bay watching a technician pull needle rollers off a three-month-old countershaft. The base number matched, but the replacement set used flat-ended standard cylindrical needles instead of the profiled X-Life geometry. Raceway spalling had already started at the roller ends — exactly where contact stress concentrates when edge loading is not corrected by the logarithmic profile. That single cross-reference oversight cost the operator an unplanned teardown and a replacement gear set. [NEED_CITE: needle roller edge stress and profiled geometry fatigue life per ISO 281]
How the 50×68×35 Envelope Fits Gearbox Design Constraints
Medium-duty gearboxes routinely demand high radial load capacity inside a tight shaft-to-housing envelope. The INA NKI50/35-XL needle roller bearing delivers that capacity within its 50 mm bore, 68 mm OD, and 35 mm width — dimensions that let designers keep shaft stiffness high without enlarging the housing bore. In transmission countershaft layouts, this compact section leaves room for adjacent gear clusters and synchronizer sleeves. When we match this bearing for a customer, we verify not just the base envelope but also the roller profile suffix, because a dimensional match alone will not prevent field failures under thermal cycling.
Radial Loads, Thermal Swings, and the Open-Type Lubrication Decision
The dominant load on a gearbox needle stage is pure radial, often with moderate shock from gear mesh impulses. Operating temperatures inside a splash-lubricated housing typically sit between 60 °C and 90 °C during continuous duty, which means thermal expansion of the shaft can shift the effective interference fit on the inner raceway. The open-type construction of this bearing allows the housing oil bath or circulating system to flush directly through the roller set, carrying away friction heat and wear debris — a clear advantage over sealed variants in contaminated or high-temperature sump conditions. [NEED_CITE: open-type needle roller bearing lubrication circulation in gearbox sumps]
Decoding the Steel Cage and X-Life Roller Profile
The steel cage on this bearing provides dimensional stability at the moderate speeds typical of industrial gearbox intermediate shafts, where centrifugal forces on the cage are manageable and vibration resistance matters more than ultra-high speed capability. X-Life designation signals that the rollers use a profiled logarithmic end geometry, which spreads contact stress evenly across the raceway instead of concentrating it at the roller tips. For a 50 mm bore needle set carrying continuous radial load, that stress distribution directly translates to noticeably extended L10 life compared to flat-ended standard rollers. The 35 mm width gives a generous roller length-to-diameter ratio, increasing the total contact area and lowering unit pressure on the raceway.
The Hidden Cost of a Base-Number-Only Cross-Reference
Procurement teams often match the base designation — NKI50/35 — and assume interchangeability across any supplier catalog. But ignoring the XL suffix means accepting standard-profile rollers that lack the edge-stress correction engineered into the X-Life series. Under sustained radial load, those flat-ended rollers generate contact stress peaks at their extremities, triggering subsurface fatigue and premature spalling classified under ISO 15243 as surface-originated fatigue failure. The downstream cost is never just the bearing itself: it is the unplanned downtime, the collateral damage to mating gears and shafts, and the voided equipment warranty when the OEM specifies X-Life geometry. [NEED_CITE: rolling bearing failure mode classification per ISO 15243]
How Verification Works Before Shipment
We source the INA NKI50/35-XL needle roller bearing through authorized distributor channels, which means every batch arrives with a Certificate of Conformity tied to the production lot number. Before we confirm a cross-reference for a customer’s gearbox application, we check the roller profile designation, cage material, and dimensional envelope together — not just the bore and OD. When a buyer needs import documentation, we supply the country-of-origin certificate and HS code details so customs clearance proceeds without delay. Our dimensional inspection on critical parameters (Fw, D, B) catches tolerance drift before the bearing ever reaches the assembly bench.
Documentation & Authenticity
- Supplier Certificate of Conformity linking each INA NKI50/35-XL shipment to its production batch and authorized channel origin
- QR code verification via the official INA app, confirming the X-Life series designation and lot integrity before installation
- Third-party dimensional inspection report covering the 50 mm bore, 68 mm OD, and 35 mm width against published tolerances
- Country-of-origin certificate and HS code documentation for gearbox builders importing into regions with strict customs traceability requirements
Storage, Handling & Mounting
- Retain the sealed factory packaging until the gearbox assembly cell is ready; early exposure risks moisture ingress on the open-type roller set, which has no integral seal to protect the raceway surfaces
- Store horizontally on a flat shelf to prevent cage distortion on the 35 mm wide steel-cage assembly — vertical stacking of loose bearings can bend cage pockets over time
- Use clean, lint-free gloves when handling; fingerprint acids on the exposed needle rollers accelerate corrosion in the absence of the oil bath lubrication the bearing will see in service
- Verify shaft diameter and surface finish against INA mounting specifications before pressing the inner race onto the gearbox shaft; interference fit errors on a 50 mm bore needle bearing cause immediate roller skewing and cage stress
Request a Technical Match
Share your gearbox operating parameters — radial load, shaft speed, sump temperature, and lubrication method — so we can confirm whether the INA NKI50/35-XL needle roller bearing is the correct selection for your specific duty cycle. If you are replacing an existing bearing, provide the OEM equipment number or the full designation printed on the removed unit so we can run a complete cross-reference check including roller profile and cage compatibility.
Frequently Asked Questions
Q: How do I verify that my INA NKI50/35-XL is genuine?
A: Each bearing carries a laser-etched QR code that links to INA’s official verification app. Scanning confirms the production batch, series designation, and authorized distribution channel. We also supply a Certificate of Conformity with every shipment so you have a paper trail for your quality management system.
Q: What dimensions should I check when replacing a needle roller bearing in a gearbox?
A: The three critical envelope dimensions are the bore diameter (Fw = 50 mm), outside diameter (D = 68 mm), and width (B = 35 mm). Beyond these, verify the cage material and roller profile designation, because a dimensional match alone does not guarantee load capacity equivalence under sustained radial service.
Q: What does the XL suffix mean for performance?
A: The XL suffix identifies INA’s X-Life series, which features profiled roller geometry designed to distribute contact stress evenly across the raceway. This reduces edge loading and extends fatigue life compared to standard flat-ended needle rollers in the same envelope dimensions.
Q: Can I use oil-bath lubrication with this open-type bearing?
A: Yes. The open construction is designed for applications where the housing provides external lubrication — such as oil splash or circulating oil systems in gearboxes. Ensure the oil viscosity grade matches the operating temperature and speed conditions specified by the equipment manufacturer.
Q: Are cross-brand equivalents available for this needle roller bearing?
A: Cross-brand interchange is possible but requires alignment on three factors simultaneously: dimensional envelope, cage material, and roller profile geometry. Submit your full application parameters and we will check compatibility across major brands, not just base number matches.
Confirm Your INA NKI50/35-XL Availability
Send us your required quantity, target delivery window, and any OEM equipment references so we can verify batch availability and prepare your documentation package. Contact our technical sales team through your regional distributor channel or submit an inquiry with your application details for a same-day cross-reference review.
