NK42-30-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 NK42-30-XL model number is decoded

envelope 42×52×30 mm: 42 mm seat is the hardened and ground shaft journal itself — there is no inner ring, with a thin 5.0 mm radial section packed with small-diameter needle rollers C is 44.5 kN and C0 82 kN at the 42 mm seat; the C/C0 ratio of 0.54 is characteristic of a needle bearing — high static rating relative to dynamic in a compact 52 mm outside diameter the fatigue load limit Cur is 15.5 kN, the limiting speed 10,900 r/min and the thermal reference speed 6,400 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 1.48 kN/mm — the reason 30 mm-wide needle bearings routinely replace much larger ball or roller positions mass is 130 g, just 0.08 g per mm² of projected 52×30 mm envelope, which keeps unbalanced forces low in fast-actuating linkages 42 mm bore marks the medium range: mounting forces and fits become critical, and the 130 g mass calls for proper induction or press tooling rather than hand fitting The hardness requirement is unforgiving: below about 58 HRC the 42 mm journal brinels under the 82 kN static rating, and roughness above raceway finish accelerates roller wear Omitting the inner ring frees radial space — at a 42 mm shaft the outer diameter is only 52 mm and the width 30 mm, yet C is 44.5 kN -XL means this is an X-life bearing — Schaeffler's upgraded performance level with smoother raceways, so the 44.5 kN C rating and longer nominal life come without an envelope change. Typical applications include copying and printing machine mechanisms, gearbox selector and change linkages and hydraulic and pneumatic pump eccentrics, where the 52 mm outside diameter and 44.5 kN dynamic rating match the duty. In copying and printing machine mechanisms the unit fits a compact 42 mm seat, and in gearbox selector and change linkages the 130 g mass keeps unbalanced forces low in fast linkages. Designers also specify it for hydraulic and pneumatic pump eccentrics, relying on the 30 mm width and the published 82 kN static rating. Keep the specified radial clearance; an oversized shaft or heavy interference removes it and the needles bind hot immediately. On reciprocating duty ensure the stroke rotates the full needle set, or brinelling occurs at the same roller positions.

Typical equipment & failure modes

Selection pitfalls — read before you substitute

• Keep the specified radial clearance; an oversized shaft or heavy interference removes it and the needles bind hot immediately.
• On reciprocating duty ensure the stroke rotates the full needle set, or brinelling occurs at the same roller positions.
• Needle bearings are pure-radial units — any thrust must be taken by separate washers or an adjacent bearing, especially on flangeless RNAO/NAO.