NKI75-25-XL bearing: complete specifications & equivalents

Specification table

Source: catalog reference (HR1 2026-09-25) · extracted 2026-09-30

Parameters extracted from the official FAG Rolling Bearings catalogue (HR1 2026-09-25); FAG® is a trademark of Schaeffler Technologies AG & Co. KG, used here for identification only — mpnbase is not an authorized FAG/Schaeffler distributor. Boundary dimensions are ISO 15 interchangeable; current production values may differ, verify at schaeffler.com.

Cross references & equivalents

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 NKI75-25-XL model number is decoded

envelope 75×105×25 mm: 75 mm bore accepts a normal-tolerance machined shaft via the integral inner ring, with a thin 15.0 mm radial section packed with small-diameter needle rollers C is 78 kN and C0 123 kN at the 75 mm seat; the C/C0 ratio of 0.63 is characteristic of a needle bearing — high static rating relative to dynamic in a compact 105 mm outside diameter the fatigue load limit Cur is 22.1 kN, the limiting speed 5,400 r/min and the thermal reference speed 3,300 r/min; for small needle bearings the reference speed can exceed the kinematic limit, so the lower of the two governs the application dynamic capacity per millimetre of bore is 1.04 kN/mm and per millimetre of width 3.12 kN/mm — the reason 25 mm-wide needle bearings routinely replace much larger ball or roller positions mass is 641 g, just 0.24 g per mm² of projected 105×25 mm envelope, which keeps unbalanced forces low in fast-actuating linkages with a 75 mm bore this is a heavy-industrial bearing: 641 g of stiff ring and roller set, specified where rigidity matters more than speed This is the choice for OEM production on soft shafts: machine the 75 mm seat to the recommended tolerance, fit the bearing, and let the inner ring provide the precision raceway The 15.0 mm section still holds a full needle pack; like all needle bearings it cannot tolerate angular misalignment, so shaft and housing axes must be parallel The -XL suffix marks the X-life execution: refined raceway topography and upgraded materials lift the basic ratings versus the non-X-life bearing at the same 75×105×25 mm envelope. Typical applications include rocker arms and valve trains, two-stroke and compressor piston pins and small electric motor accessory drives, where the 105 mm outside diameter and 78 kN dynamic rating match the duty. In rocker arms and valve trains the unit fits a compact 75 mm seat, and in two-stroke and compressor piston pins the 641 g mass keeps unbalanced forces low in fast linkages. Designers also specify it for small electric motor accessory drives, relying on the 25 mm width and the published 123 kN static rating. Open ends draw contamination directly onto the needles; specify sealed or shielded positions in dusty environments rather than relying on grease alone. Adding an IR inner ring changes the envelope logic: the same outer assembly then fits a smaller shaft — recheck bore, clearance and ratings when substituting.

Typical equipment & failure modes

Selection pitfalls — read before you substitute

• Open ends draw contamination directly onto the needles; specify sealed or shielded positions in dusty environments rather than relying on grease alone.
• Adding an IR inner ring changes the envelope logic: the same outer assembly then fits a smaller shaft — recheck bore, clearance and ratings when substituting.
• Keep the specified radial clearance; an oversized shaft or heavy interference removes it and the needles bind hot immediately.