NA4903-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 NA4903-XL model number is decoded

envelope 17×30×13 mm: 17 mm bore accepts a normal-tolerance machined shaft via the integral inner ring, with a thin 6.5 mm radial section packed with small-diameter needle rollers C is 12.4 kN and C0 14.6 kN at the 17 mm seat; the C/C0 ratio of 0.85 is characteristic of a needle bearing — high static rating relative to dynamic in a compact 30 mm outside diameter the fatigue load limit Cur is 2.65 kN, the limiting speed 20,000 r/min and the thermal reference speed 10,200 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 0.73 kN/mm and per millimetre of width 0.95 kN/mm — the reason 13 mm-wide needle bearings routinely replace much larger ball or roller positions mass is 37 g, just 0.09 g per mm² of projected 30×13 mm envelope, which keeps unbalanced forces low in fast-actuating linkages with a 17 mm bore the 13 mm width and 12.4 kN C rating suit high-cycle industrial machinery rather than instrument duty Cur 2.65 kN, limiting speed 20,000 r/min, reference speed 10,200 r/min — the inner ring adds a few grams (total 37 g) but removes the hardening requirement The inner ring is separable, so the outer-ring/roller assembly can be pressed into the housing first; the 14.6 kN C0 rating still assumes full rigid support under both rings 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 20,000 r/min limit. Typical applications include planetary gear bearings, small electric motor accessory drives and gearbox selector and change linkages, where the 30 mm outside diameter and 12.4 kN dynamic rating match the duty. In planetary gear bearings the unit fits a compact 17 mm seat, and in small electric motor accessory drives the 37 g mass keeps unbalanced forces low in fast linkages. Designers also specify it for gearbox selector and change linkages, relying on the 13 mm width and the published 14.6 kN static rating. On reciprocating duty ensure the stroke rotates the full needle set, or brinelling occurs at the same roller positions. 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.

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.
• 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.
• 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.