NKI42-20-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 NKI42-20-XL model number is decoded

envelope 42×57×20 mm: 42 mm bore accepts a normal-tolerance machined shaft via the integral inner ring, with a thin 7.5 mm radial section packed with small-diameter needle rollers C is 32.5 kN and C0 56 kN at the 42 mm seat; the C/C0 ratio of 0.58 is characteristic of a needle bearing — high static rating relative to dynamic in a compact 57 mm outside diameter the fatigue load limit Cur is 10.1 kN, the limiting speed 9,800 r/min and the thermal reference speed 5,600 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 0.77 kN/mm and per millimetre of width 1.63 kN/mm — the reason 20 mm-wide needle bearings routinely replace much larger ball or roller positions mass is 148 g, just 0.13 g per mm² of projected 57×20 mm envelope, which keeps unbalanced forces low in fast-actuating linkages at 42 mm bore this is a mainstream industrial size — conveyor drives, winches and medium gearboxes use the 20 mm width as a standard mounting space This is the choice for OEM production on soft shafts: machine the 42 mm seat to the recommended tolerance, fit the bearing, and let the inner ring provide the precision raceway NKI42/20-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 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 9,800 r/min limit. Typical applications include planetary gear bearings, small electric motor accessory drives and gearbox selector and change linkages, where the 57 mm outside diameter and 32.5 kN dynamic rating match the duty. In planetary gear bearings the unit fits a compact 42 mm seat, and in small electric motor accessory drives the 148 g mass keeps unbalanced forces low in fast linkages. Designers also specify it for gearbox selector and change linkages, relying on the 20 mm width and the published 56 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. Open ends draw contamination directly onto the needles; specify sealed or shielded positions in dusty environments rather than relying on grease alone.

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.
• Open ends draw contamination directly onto the needles; specify sealed or shielded positions in dusty environments rather than relying on grease alone.
• Without an inner ring the shaft is the raceway: 58–64 HRC and a ground, polished journal are mandatory, not recommendations.