NA4918-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 NA4918-XL model number is decoded

envelope 90×125×35 mm: 90 mm bore accepts a normal-tolerance machined shaft via the integral inner ring, with a thin 17.5 mm radial section packed with small-diameter needle rollers C is 129 kN and C0 250 kN at the 90 mm seat; the C/C0 ratio of 0.52 is characteristic of a needle bearing — high static rating relative to dynamic in a compact 125 mm outside diameter the fatigue load limit Cur is 44.5 kN, the limiting speed 4,400 r/min and the thermal reference speed 2,500 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 1.43 kN/mm and per millimetre of width 3.69 kN/mm — the reason 35 mm-wide needle bearings routinely replace much larger ball or roller positions mass is 1.312 kg (1312 g), just 0.30 g per mm² of projected 125×35 mm envelope, which keeps unbalanced forces low in fast-actuating linkages at 90 mm bore the 125 mm outside diameter and 35 mm width target rolling stands, construction machinery and heavy gearboxes; the limiting speed drops to 4,400 r/min Cur 44.5 kN, limiting speed 4,400 r/min, reference speed 2,500 r/min — the inner ring adds a few grams (total 1312 g) but removes the hardening requirement As an X-life (-XL) bearing it benefits from the optimised surface finish that reduces friction and raises the fatigue strength behind the 44.5 kN Cur value. Typical applications include gearbox selector and change linkages, planetary gear bearings and copying and printing machine mechanisms, where the 125 mm outside diameter and 129 kN dynamic rating match the duty. In gearbox selector and change linkages the unit fits a compact 90 mm seat, and in planetary gear bearings the 1.312 kg mass is part of the rotor inertia calculation. Designers also specify it for copying and printing machine mechanisms, relying on the 35 mm width and the published 250 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. Without an inner ring the shaft is the raceway: 58–64 HRC and a ground, polished journal are mandatory, not recommendations.

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.
• Without an inner ring the shaft is the raceway: 58–64 HRC and a ground, polished journal are mandatory, not recommendations.
• On reciprocating duty ensure the stroke rotates the full needle set, or brinelling occurs at the same roller positions.