NK47-20-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 NK47-20-XL model number is decoded

envelope 47×57×20 mm: 47 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 32.5 kN and C0 56 kN at the 47 mm seat; the C/C0 ratio of 0.58 is characteristic of a needle bearing — high static rating relative to dynamic in a compact 57 mm outside diameter the fatigue load limit Cur is 10.1 kN, the limiting speed 9,800 r/min and the thermal reference speed 6,000 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 0.69 kN/mm and per millimetre of width 1.63 kN/mm — the reason 20 mm-wide needle bearings routinely replace much larger ball or roller positions mass is 94.5 g, just 0.08 g per mm² of projected 57×20 mm envelope, which keeps unbalanced forces low in fast-actuating linkages 47 mm bore marks the medium range: mounting forces and fits become critical, and the 94.5 g mass calls for proper induction or press tooling rather than hand fitting Reading the NK prefix: a machined (not drawn-cup) outer ring with the needle complement; an inner ring from the IR series can be added later if the shaft cannot be hardened The hardness requirement is unforgiving: below about 58 HRC the 47 mm journal brinels under the 56 kN static rating, and roughness above raceway finish accelerates roller wear X-life status (-XL) indicates the current Schaeffler premium execution at 47 mm bore; the 56 kN C0 rating reflects the improved rolling-contact geometry. Typical applications include motorcycle and light-vehicle transmissions, connecting-rod small ends and two-stroke and compressor piston pins, where the 57 mm outside diameter and 32.5 kN dynamic rating match the duty. In motorcycle and light-vehicle transmissions the unit fits a compact 47 mm seat, and in connecting-rod small ends the 94.5 g mass keeps unbalanced forces low in fast linkages. Designers also specify it for two-stroke and compressor piston pins, relying on the 20 mm width and the published 56 kN static rating. Open ends draw contamination directly onto the needles; specify sealed or shielded positions in dusty environments rather than relying on grease alone. Keep the specified radial clearance; an oversized shaft or heavy interference removes it and the needles bind hot immediately.

Typical equipment & failure modes

Selection pitfalls — read before you substitute

• Open ends draw contamination directly onto the needles; specify sealed or shielded positions in dusty environments rather than relying on grease alone.
• 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.