NK70-25-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 NK70-25-XL model number is decoded

envelope 70×85×25 mm: 70 mm seat is the hardened and ground shaft journal itself — there is no inner ring, with a thin 7.5 mm radial section packed with small-diameter needle rollers C is 50 kN and C0 92 kN at the 70 mm seat; the C/C0 ratio of 0.54 is characteristic of a needle bearing — high static rating relative to dynamic in a compact 85 mm outside diameter the fatigue load limit Cur is 16 kN, the limiting speed 6,600 r/min and the thermal reference speed 4,450 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 2.00 kN/mm — the reason 25 mm-wide needle bearings routinely replace much larger ball or roller positions mass is 260 g, just 0.12 g per mm² of projected 85×25 mm envelope, which keeps unbalanced forces low in fast-actuating linkages the 70 mm bore belongs to the large band, where HR1 full-complement and track-roller designs deliver their highest kilonewton ratings in slow, heavily loaded machinery The hardness requirement is unforgiving: below about 58 HRC the 70 mm journal brinels under the 92 kN static rating, and roughness above raceway finish accelerates roller wear The thin 7.5 mm section makes the 260 g bearing sensitive to seat geometry — a tapered or lobed journal preloads part of the needle set and shows up as local pitting As an X-life (-XL) bearing it benefits from the optimised surface finish that reduces friction and raises the fatigue strength behind the 16 kN Cur value. Typical applications include motorcycle and light-vehicle transmissions, connecting-rod small ends and two-stroke and compressor piston pins, where the 85 mm outside diameter and 50 kN dynamic rating match the duty. In motorcycle and light-vehicle transmissions the unit fits a compact 70 mm seat, and in connecting-rod small ends the 260 g mass keeps unbalanced forces low in fast linkages. Designers also specify it for two-stroke and compressor piston pins, relying on the 25 mm width and the published 92 kN static rating. Without an inner ring the shaft is the raceway: 58–64 HRC and a ground, polished journal are mandatory, not recommendations. 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

• Without an inner ring the shaft is the raceway: 58–64 HRC and a ground, polished journal are mandatory, not recommendations.
• On reciprocating duty ensure the stroke rotates the full needle set, or brinelling occurs at the same roller positions.
• 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.