Description
Traceable Supply Chain — Every INA NK24/16-XL needle roller bearing we source ships with Schaeffler-authorized distributor documentation and batch-level traceability.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | INA NK24/16-XL |
| Bearing Type | Needle Roller Bearing |
| Bore Diameter (Fw) | 24 mm |
| Outside Diameter (D) | 32 mm |
| Width (B) | 16 mm |
| Weight | 0.32 kg |
| Cage Material | Bearing Steel Cage |
| Seal or Shield Type | Open |
| Number of Rows | Single |
| Arrangement | Without Inner Ring, Without Outer Ring |
| Load Direction | Radial |
| Origin | INA (Schaeffler Group) |
Note: The "-XL" suffix on this designation is unverified and requires confirmation against the current Schaeffler product catalog for exact specification impact.
Application Suitability
| Industry | Typical Applications |
|---|---|
| Automotive & Heavy Vehicle | Motorcycle transmission countershafts, gearbox laygear assemblies |
| Industrial Machinery | Compact radial support in textile machinery guide rollers |
| General MRO | Replacement needle sets for legacy powertrain rebuilds |
What Happens When a Soft Roller Enters Your Transmission
A micro-cracked inner surface on a needle roller is rarely visible until the gearbox is already contaminated with steel debris.
In motorcycle transmissions and high-vibration industrial gearboxes, the INA NK24/16-XL needle roller bearing operates without inner or outer rings, meaning the shaft and housing bore act directly as raceways. If a counterfeit or substandard batch enters your supply chain, the needle rollers often lack proper carburizing depth. Under load, the surface spalls within weeks, shedding metallic particles that destroy adjacent gears. The downtime cost of pulling a transmission apart far exceeds the initial bearing savings, and tracing the root cause back to a forged hardness certificate is frustratingly common [NEED_CITE: rolling bearing failure mode classification per ISO 15243].
Why the NK Series Dominates Space-Constrained Drivetrains
The INA NK24/16-XL needle roller bearing achieves high radial load capacity within a remarkably small cross-section. Because this design eliminates both inner and outer rings, the needle rollers run directly on a hardened shaft surface and a hardened housing bore. For motorcycle transmissions where every millimeter of radial space matters, this configuration delivers the load-bearing surface area of a much larger conventional bearing. We frequently cross-check this profile against legacy OEM equipment numbers to ensure the 24 mm bore, 32 mm outside diameter, and 16 mm width match exactly, because even slight dimensional drift in a ringless needle bearing causes edge-loading and rapid cage wear.
The Operating Environment These Rollers Actually Face
Inside a motorcycle gearbox, this bearing endures combined shock loading from gear engagement, frequent rotational direction reversals, and oil splash lubrication that may carry metallic wear particles from nearby clutch plates. The open-type construction of the INA NK24/16-XL means lubrication flows freely through the cage and roller interface, which is essential for heat dissipation at transmission operating temperatures. However, it also places full responsibility for contamination control on the gearbox housing seals. When rebuilds happen in field workshops rather than clean assembly environments, the absence of integrated seals means any ingress of abrasive particles directly contacts the rolling elements [NEED_CITE: needle roller bearing contamination sensitivity in enclosed gearboxes].
Reading Between the Lines of the Specification Sheet
The single-row needle roller configuration without rings means the bearing steel cage must maintain precise roller spacing under fluctuating radial loads. The open type designation tells us there are no contact seals generating friction heat, which is critical when the bearing sits inside a splash-lubricated transmission housing. At 24 mm bore and 16 mm width, the load path through the rollers is concentrated over a small contact ellipse, demanding that the shaft surface hardness reaches at least 58 HRC and the surface roughness stays within Ra 0.2 µm to prevent premature roller skidding. The cage design governs maximum permissible speed; a stamped steel cage with guided rollers allows higher rpm than a full-complement arrangement but requires consistent oil film thickness.
The Hidden Price of a Dimensional Shortcut
When a procurement decision focuses solely on unit price, the risk of receiving needle rollers with incorrect diameter tolerances increases substantially. Even a deviation of a few microns across a single roller in a set creates unequal load sharing. The overloaded roller develops subsurface fatigue cracks, which propagate to the surface and initiate spalling. According to ISO 281, the basic rating life calculation assumes uniform load distribution; when that assumption breaks down, actual service life drops disproportionately. In a motorcycle transmission, this manifests as a buzzing noise during acceleration that progresses to catastrophic cage fracture and gear seizure. We source through Schaeffler-authorized channels precisely to maintain the dimensional consistency that the L10 life calculation depends on [NEED_CITE: ISO 281 bearing life calculation assumptions load distribution].
How Our Sourcing Process Protects Your Rebuild Quality
We do not hold a single-brand distributorship; instead, we maintain active accounts with multiple Schaeffler-authorized regional distributors to secure INA NK24/16-XL needle roller bearings with complete batch traceability. Every shipment we consolidate is cross-referenced against your OEM equipment number to verify that bore diameter, width, cage type, and the open-type configuration match the original specification. Our documentation package includes Certificate of Conformity, material certificates confirming bearing steel grade, and dimensional inspection data. For buyers in regions where counterfeit bearings circulate through unverified trading channels, we provide QR code verification pathways through Schaeffler’s official applications, giving your receiving inspection team a definitive authenticity check before the batch enters inventory.
Documentation & Authenticity
- Supplier Certificate of Conformity (COC) tied to the specific INA batch and lot number for full upstream traceability.
- Material certificates confirming bearing steel composition and hardness specifications for the needle rollers and cage.
- QR code verification pathway via the Schaeffler official application, enabling your quality team to confirm origin on receipt.
- Dimensional inspection reports covering bore diameter, outside diameter, width, and roller diameter tolerance per ISO standards.
- Country-of-origin documentation prepared for import customs clearance and buyer-side compliance audits.
- HS code classification support to streamline import paperwork for bulk needle roller bearing consignments.
Storage, Handling & Mounting
- Keep the INA NK24/16-XL in original sealed packaging until the moment of installation; early opening exposes the open-type bearing to ambient moisture and workshop dust that can lodge between needle rollers.
- Store at stable temperatures away from direct sunlight to prevent condensation inside the packaging, which causes corrosion on the exposed bearing steel surfaces before mounting.
- Use clean, lint-free gloves during handling; fingerprint acids on the needle rollers accelerate localized corrosion, particularly on this ringless design where the rollers contact the shaft directly.
- Verify shaft surface hardness and roughness before mounting; since this bearing has no inner ring, the shaft itself serves as the raceway and must meet INA’s specified HRC and Ra values.
- Apply the recommended transmission oil or assembly lubricant to the needle rollers and cage immediately before pressing into the housing bore to prevent dry start-up damage.
- For bulk orders, inspect packaging integrity upon receipt and report any crushed cartons that may have deformed the thin-section cage structure.
Next Steps for Your Transmission Bearing Requirement
Share Your Application Parameters for Cross-Reference Verification
Send us the OEM equipment number, transmission model, or specific operating conditions (load, speed, temperature) so we can confirm the INA NK24/16-XL is the exact match for your application. We will return a cross-reference comparison, availability confirmation, and a documentation package outline within our standard response window. Reach our engineering sourcing desk at info@bearing-sourcing.com or through the inquiry form on our catalog page.
Frequently Asked Questions
Q: How can I verify the authenticity of INA needle roller bearings through official channels?
A: Schaeffler provides an official application that reads the QR code on INA product packaging. We supply bearings sourced exclusively through authorized distributor channels, so the QR code on each package will resolve to valid batch and origin data within the Schaeffler system. We also provide a Certificate of Conformity that traces back to the authorized distributor’s purchase record.
Q: What cross-reference considerations apply when substituting an INA NK24/16-XL with another brand?
A: Matching the base dimensions (24 mm bore, 32 mm OD, 16 mm width) is only the starting point. You must also align the cage material and design, confirm the open-type configuration, and verify that the replacement brand’s needle roller profile and end geometry match the INA specification. We maintain cross-brand interchange data across INA, SKF, NTN, and IKO that accounts for these factors, not just the numeric designation.
Q: What lubrication approach is appropriate for an open-type needle roller bearing in a motorcycle transmission?
A: Open-type bearings like the INA NK24/16-XL rely on the surrounding gearbox oil for lubrication and cooling. During assembly, a preliminary coating of the same transmission oil or a compatible assembly lubricant prevents dry contact on initial start-up. The gearbox design must ensure adequate oil splash or circulation reaches the bearing location under all operating speeds.
Q: What documentation package ships with a bulk order of these needle roller bearings?
A: A standard bulk shipment includes the supplier Certificate of Conformity, material certificates for the bearing steel, dimensional inspection data, batch and lot traceability records, and country-of-origin documentation. We also provide HS code details to assist your import clearance process.
Q: What are typical lead times for less common needle roller bearing designations?
A: Lead times depend on current stock positions at our authorized distributor network. Common NK series sizes are often available from regional inventory, while specialized suffixes or large batch quantities may require scheduled production releases. We confirm exact availability and transit time at the quotation stage based on your required quantity.
Confirm Your INA NK24/16-XL Requirement
Send us your OEM equipment number or application parameters, and we will return a verified cross-reference, sourcing timeline, and full documentation outline. Contact our team at info@bearing-sourcing.com.
