NK43-20-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 NK43-20-XL model number is decoded

envelope 43×53×20 mm: 43 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 30.5 kN and C0 51 kN at the 43 mm seat; the C/C0 ratio of 0.60 is characteristic of a needle bearing — high static rating relative to dynamic in a compact 53 mm outside diameter the fatigue load limit Cur is 9.1 kN, the limiting speed 10,700 r/min and the thermal reference speed 6,500 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 0.71 kN/mm and per millimetre of width 1.52 kN/mm — the reason 20 mm-wide needle bearings routinely replace much larger ball or roller positions mass is 86 g, just 0.08 g per mm² of projected 53×20 mm envelope, which keeps unbalanced forces low in fast-actuating linkages at 43 mm bore this is a mainstream industrial size — conveyor drives, winches and medium gearboxes use the 20 mm width as a standard mounting space 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 This bearing accepts axial displacement between shaft and housing because the rollers rotate on the free journal; it locates nothing axially and must be flanked by guide faces As an X-life (-XL) bearing it benefits from the optimised surface finish that reduces friction and raises the fatigue strength behind the 9.1 kN Cur value. Typical applications include connecting-rod small ends, textile machine heald and cam shafts and motorcycle and light-vehicle transmissions, where the 53 mm outside diameter and 30.5 kN dynamic rating match the duty. In connecting-rod small ends the unit fits a compact 43 mm seat, and in textile machine heald and cam shafts the 86 g mass keeps unbalanced forces low in fast linkages. Designers also specify it for motorcycle and light-vehicle transmissions, relying on the 20 mm width and the published 51 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. 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

• 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.
• 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.