NAO25X40X17-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 NAO25X40X17-XL model number is decoded

envelope 25×40×17 mm: 25 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 22.1 kN and C0 34 kN at the 25 mm seat; the C/C0 ratio of 0.65 is characteristic of a needle bearing — high static rating relative to dynamic in a compact 40 mm outside diameter the fatigue load limit Cur is 5.4 kN, the limiting speed 15,100 r/min and the thermal reference speed 8,100 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 0.88 kN/mm and per millimetre of width 1.30 kN/mm — the reason 17 mm-wide needle bearings routinely replace much larger ball or roller positions mass is 88 g, just 0.13 g per mm² of projected 40×17 mm envelope, which keeps unbalanced forces low in fast-actuating linkages the 25 mm bore falls in the small band, the workhorse size for gearbox planetary positions, hydraulic pumps and general cam and linkage duty Because neither ring guides axially, housing and shaft shoulders position the races; uncontrolled end float lets the rollers run off the raceway edges The single needle row fills the thin section, with limiting speed 15,100 r/min and reference speed 8,100 r/min X-life status (-XL) indicates the current Schaeffler premium execution at 25 mm bore; the 34 kN C0 rating reflects the improved rolling-contact geometry. Typical applications include rocker arms and valve trains, two-stroke and compressor piston pins and small electric motor accessory drives, where the 40 mm outside diameter and 22.1 kN dynamic rating match the duty. In rocker arms and valve trains the unit fits a compact 25 mm seat, and in two-stroke and compressor piston pins the 88 g mass keeps unbalanced forces low in fast linkages. Designers also specify it for small electric motor accessory drives, relying on the 17 mm width and the published 34 kN static rating. On reciprocating duty ensure the stroke rotates the full needle set, or brinelling occurs at the same roller positions. 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

• On reciprocating duty ensure the stroke rotates the full needle set, or brinelling occurs at the same roller positions.
• Open ends draw contamination directly onto the needles; specify sealed or shielded positions in dusty environments rather than relying on grease alone.
• 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.