NKIS50-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 NKIS50-XL model number is decoded

envelope 50×80×28 mm: 50 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 71 kN and C0 98 kN at the 50 mm seat; the C/C0 ratio of 0.72 is characteristic of a needle bearing — high static rating relative to dynamic in a compact 80 mm outside diameter the fatigue load limit Cur is 17.6 kN, the limiting speed 7,400 r/min and the thermal reference speed 4,250 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 1.42 kN/mm and per millimetre of width 2.54 kN/mm — the reason 28 mm-wide needle bearings routinely replace much larger ball or roller positions mass is 518 g, just 0.23 g per mm² of projected 80×28 mm envelope, which keeps unbalanced forces low in fast-actuating linkages the 50 mm bore places this bearing in the medium band, where the 80 mm envelope already carries ratings in the tens of kilonewtons 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 NKIS50-XL is supplied with a machined inner ring, so it mounts on an ordinary turned and ground shaft of normal tolerance — hardening the journal is not required X-life status (-XL) indicates the current Schaeffler premium execution at 50 mm bore; the 98 kN C0 rating reflects the improved rolling-contact geometry. Typical applications include hydraulic and pneumatic pump eccentrics, copying and printing machine mechanisms and agricultural machine pivots and linkages, where the 80 mm outside diameter and 71 kN dynamic rating match the duty. In hydraulic and pneumatic pump eccentrics the unit fits a compact 50 mm seat, and in copying and printing machine mechanisms the 518 g mass keeps unbalanced forces low in fast linkages. Designers also specify it for agricultural machine pivots and linkages, relying on the 28 mm width and the published 98 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.
• Without an inner ring the shaft is the raceway: 58–64 HRC and a ground, polished journal are mandatory, not recommendations.