NA6910-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 NA6910-ZW-XL model number is decoded

envelope 50×72×40 mm: 50 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 82 kN and C0 139 kN at the 50 mm seat; the C/C0 ratio of 0.59 is characteristic of a needle bearing — high static rating relative to dynamic in a compact 72 mm outside diameter the fatigue load limit Cur is 23.8 kN, the limiting speed 7,800 r/min and the thermal reference speed 4,200 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 1.64 kN/mm and per millimetre of width 2.05 kN/mm — the reason 40 mm-wide needle bearings routinely replace much larger ball or roller positions mass is 515 g, just 0.18 g per mm² of projected 72×40 mm envelope, which keeps unbalanced forces low in fast-actuating linkages at 50 mm bore this is a mainstream industrial size — conveyor drives, winches and medium gearboxes use the 40 mm width as a standard mounting space 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 The -XL suffix marks the X-life execution: refined raceway topography and upgraded materials lift the basic ratings versus the non-X-life bearing at the same 50×72×40 mm envelope. Reading -ZW: two needle rows instead of one; the load is spread over the 40 mm width while the outside diameter stays a compact 72 mm. Typical applications include small electric motor accessory drives, rocker arms and valve trains and planetary gear bearings, where the 72 mm outside diameter and 82 kN dynamic rating match the duty. In small electric motor accessory drives the unit fits a compact 50 mm seat, and in rocker arms and valve trains the 515 g mass keeps unbalanced forces low in fast linkages. Designers also specify it for planetary gear bearings, relying on the 40 mm width and the published 139 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. 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.

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.
• 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.