NKIS40-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 NKIS40-XL model number is decoded

envelope 40×65×22 mm: 40 mm bore accepts a normal-tolerance machined shaft via the integral inner ring, with a thin 12.5 mm radial section packed with small-diameter needle rollers C is 48 kN and C0 67 kN at the 40 mm seat; the C/C0 ratio of 0.72 is characteristic of a needle bearing — high static rating relative to dynamic in a compact 65 mm outside diameter the fatigue load limit Cur is 11.8 kN, the limiting speed 8,900 r/min and the thermal reference speed 4,850 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 1.20 kN/mm and per millimetre of width 2.18 kN/mm — the reason 22 mm-wide needle bearings routinely replace much larger ball or roller positions mass is 281 g, just 0.20 g per mm² of projected 65×22 mm envelope, which keeps unbalanced forces low in fast-actuating linkages the 40 mm bore places this bearing in the medium band, where the 65 mm envelope already carries ratings in the tens of kilonewtons Reading the NKIS prefix: machined-ring needle bearing with inner ring, one roller row, capable of pure radial load at 48 kN C Cur 11.8 kN, limiting speed 8,900 r/min, reference speed 4,850 r/min — the inner ring adds a few grams (total 281 g) but removes the hardening requirement The -XL suffix is the Schaeffler X-life mark: interchangeable envelope with the basic bearing, but higher load capacity and lower running temperature at the 8,900 r/min limit. Typical applications include rocker arms and valve trains, two-stroke and compressor piston pins and small electric motor accessory drives, where the 65 mm outside diameter and 48 kN dynamic rating match the duty. In rocker arms and valve trains the unit fits a compact 40 mm seat, and in two-stroke and compressor piston pins the 281 g mass keeps unbalanced forces low in fast linkages. Designers also specify it for small electric motor accessory drives, relying on the 22 mm width and the published 67 kN static rating. 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.

Typical equipment & failure modes

Selection pitfalls — read before you substitute

• 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.
• Do not press an RNA/NK assembly in through the outer ring when mounting it on a shaft, and vice versa — rolling forces through the wrong ring bruises the raceways.