NK12-12-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 NK12-12-XL model number is decoded

envelope 12×19×12 mm: 12 mm seat is the hardened and ground shaft journal itself — there is no inner ring, with a thin 3.5 mm radial section packed with small-diameter needle rollers C is 7.2 kN and C0 7.1 kN at the 12 mm seat; the C/C0 ratio of 1.01 is characteristic of a needle bearing — high static rating relative to dynamic in a compact 19 mm outside diameter the fatigue load limit Cur is 1.31 kN, the limiting speed 26,500 r/min and the thermal reference speed 22,400 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 0.60 kN/mm and per millimetre of width 0.60 kN/mm — the reason 12 mm-wide needle bearings routinely replace much larger ball or roller positions mass is 12.1 g, just 0.05 g per mm² of projected 19×12 mm envelope, which keeps unbalanced forces low in fast-actuating linkages the 12 mm bore sits in the miniature band; at 12 mm wide the NK12/12-XL is built into compact cam drives, indexing pawls and light linkages 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 12 mm journal brinels under the 7.1 kN static rating, and roughness above raceway finish accelerates roller wear 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 12×19×12 mm envelope. Typical applications include connecting-rod small ends, textile machine heald and cam shafts and motorcycle and light-vehicle transmissions, where the 19 mm outside diameter and 7.2 kN dynamic rating match the duty. In connecting-rod small ends the unit fits a compact 12 mm seat, and in textile machine heald and cam shafts the 12.1 g mass keeps unbalanced forces low in fast linkages. Designers also specify it for motorcycle and light-vehicle transmissions, relying on the 12 mm width and the published 7.1 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.