NK25-16-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 NK25-16-XL model number is decoded

envelope 25×33×16 mm: 25 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 16.8 kN and C0 22.4 kN at the 25 mm seat; the C/C0 ratio of 0.75 is characteristic of a needle bearing — high static rating relative to dynamic in a compact 33 mm outside diameter the fatigue load limit Cur is 4.2 kN, the limiting speed 17,800 r/min and the thermal reference speed 10,700 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 0.67 kN/mm and per millimetre of width 1.05 kN/mm — the reason 16 mm-wide needle bearings routinely replace much larger ball or roller positions mass is 32.6 g, just 0.06 g per mm² of projected 33×16 mm envelope, which keeps unbalanced forces low in fast-actuating linkages at 25 mm bore this size balances the 33 mm outside diameter against machineability of the adjacent parts — the most frequently specified band in the HR1 range The hardness requirement is unforgiving: below about 58 HRC the 25 mm journal brinels under the 22.4 kN static rating, and roughness above raceway finish accelerates roller wear 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 17,800 r/min limit. Typical applications include agricultural machine pivots and linkages, hydraulic and pneumatic pump eccentrics and textile machine heald and cam shafts, where the 33 mm outside diameter and 16.8 kN dynamic rating match the duty. In agricultural machine pivots and linkages the unit fits a compact 25 mm seat, and in hydraulic and pneumatic pump eccentrics the 32.6 g mass keeps unbalanced forces low in fast linkages. Designers also specify it for textile machine heald and cam shafts, relying on the 16 mm width and the published 22.4 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.