NA4905-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 NA4905-XL model number is decoded

envelope 25×42×17 mm: 25 mm bore accepts a normal-tolerance machined shaft via the integral inner ring, with a thin 8.5 mm radial section packed with small-diameter needle rollers C is 26.5 kN and C0 31.5 kN at the 25 mm seat; the C/C0 ratio of 0.84 is characteristic of a needle bearing — high static rating relative to dynamic in a compact 42 mm outside diameter the fatigue load limit Cur is 5.8 kN, the limiting speed 14,400 r/min and the thermal reference speed 7,700 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 1.06 kN/mm and per millimetre of width 1.56 kN/mm — the reason 17 mm-wide needle bearings routinely replace much larger ball or roller positions mass is 88 g, just 0.12 g per mm² of projected 42×17 mm envelope, which keeps unbalanced forces low in fast-actuating linkages at 25 mm bore this size balances the 42 mm outside diameter against machineability of the adjacent parts — the most frequently specified band in the HR1 range Reading the NA49 prefix: machined-ring needle bearing with inner ring, one roller row, capable of pure radial load at 26.5 kN C Cur 5.8 kN, limiting speed 14,400 r/min, reference speed 7,700 r/min — the inner ring adds a few grams (total 88 g) but removes the hardening requirement X-life status (-XL) indicates the current Schaeffler premium execution at 25 mm bore; the 31.5 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 42 mm outside diameter and 26.5 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 31.5 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. Keep the specified radial clearance; an oversized shaft or heavy interference removes it and the needles bind hot immediately.

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.
• Keep the specified radial clearance; an oversized shaft or heavy interference removes it and the needles bind hot immediately.
• 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.