NK15-20-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 NK15-20-XL model number is decoded

envelope 15×23×20 mm: 15 mm seat is the hardened and ground shaft journal itself — there is no inner ring, with a thin 4.0 mm radial section packed with small-diameter needle rollers C is 15.4 kN and C0 17.2 kN at the 15 mm seat; the C/C0 ratio of 0.90 is characteristic of a needle bearing — high static rating relative to dynamic in a compact 23 mm outside diameter the fatigue load limit Cur is 3.05 kN, the limiting speed 23,900 r/min and the thermal reference speed 17,000 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 1.03 kN/mm and per millimetre of width 0.77 kN/mm — the reason 20 mm-wide needle bearings routinely replace much larger ball or roller positions mass is 26.6 g, just 0.06 g per mm² of projected 23×20 mm envelope, which keeps unbalanced forces low in fast-actuating linkages with a 15 mm bore the 20 mm width and 15.4 kN C rating suit high-cycle industrial machinery rather than instrument duty The hardness requirement is unforgiving: below about 58 HRC the 15 mm journal brinels under the 17.2 kN static rating, and roughness above raceway finish accelerates roller wear -XL means this is an X-life bearing — Schaeffler's upgraded performance level with smoother raceways, so the 15.4 kN C rating and longer nominal life come without an envelope change. Typical applications include hydraulic and pneumatic pump eccentrics, copying and printing machine mechanisms and agricultural machine pivots and linkages, where the 23 mm outside diameter and 15.4 kN dynamic rating match the duty. In hydraulic and pneumatic pump eccentrics the unit fits a compact 15 mm seat, and in copying and printing machine mechanisms the 26.6 g mass keeps unbalanced forces low in fast linkages. Designers also specify it for agricultural machine pivots and linkages, relying on the 20 mm width and the published 17.2 kN static rating. 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. On reciprocating duty ensure the stroke rotates the full needle set, or brinelling occurs at the same roller positions.

Typical equipment & failure modes

Selection pitfalls — read before you substitute

• 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.
• On reciprocating duty ensure the stroke rotates the full needle set, or brinelling occurs at the same roller positions.
• 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.