NA6908-ZW-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 NA6908-ZW-XL model number is decoded

envelope 40×62×40 mm: 40 mm bore accepts a normal-tolerance machined shaft via the integral inner ring, with a thin 11.0 mm radial section packed with small-diameter needle rollers C is 74 kN and C0 116 kN at the 40 mm seat; the C/C0 ratio of 0.64 is characteristic of a needle bearing — high static rating relative to dynamic in a compact 62 mm outside diameter the fatigue load limit Cur is 19.8 kN, the limiting speed 9,200 r/min and the thermal reference speed 5,100 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 1.85 kN/mm and per millimetre of width 1.85 kN/mm — the reason 40 mm-wide needle bearings routinely replace much larger ball or roller positions mass is 430 g, just 0.17 g per mm² of projected 62×40 mm envelope, which keeps unbalanced forces low in fast-actuating linkages the 40 mm bore places this bearing in the medium band, where the 62 mm envelope already carries ratings in the tens of kilonewtons Cur 19.8 kN, limiting speed 9,200 r/min, reference speed 5,100 r/min — the inner ring adds a few grams (total 430 g) but removes the hardening requirement The 11.0 mm section still holds a full needle pack; like all needle bearings it cannot tolerate angular misalignment, so shaft and housing axes must be parallel X-life status (-XL) indicates the current Schaeffler premium execution at 40 mm bore; the 116 kN C0 rating reflects the improved rolling-contact geometry. The -ZW suffix denotes a double-row (zweireihig) needle roller and cage assembly: two roller rows share the 40 mm-wide envelope for higher capacity at the same bore. Typical applications include rocker arms and valve trains, two-stroke and compressor piston pins and small electric motor accessory drives, where the 62 mm outside diameter and 74 kN dynamic rating match the duty. In rocker arms and valve trains the unit fits a compact 40 mm seat, and in two-stroke and compressor piston pins the 430 g mass keeps unbalanced forces low in fast linkages. Designers also specify it for small electric motor accessory drives, relying on the 40 mm width and the published 116 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. 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

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