NK68-25-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 NK68-25-XL model number is decoded

envelope 68×82×25 mm: 68 mm seat is the hardened and ground shaft journal itself — there is no inner ring, with a thin 7.0 mm radial section packed with small-diameter needle rollers C is 49.5 kN and C0 89 kN at the 68 mm seat; the C/C0 ratio of 0.56 is characteristic of a needle bearing — high static rating relative to dynamic in a compact 82 mm outside diameter the fatigue load limit Cur is 15.5 kN, the limiting speed 6,800 r/min and the thermal reference speed 4,500 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 0.73 kN/mm and per millimetre of width 1.98 kN/mm — the reason 25 mm-wide needle bearings routinely replace much larger ball or roller positions mass is 241 g, just 0.12 g per mm² of projected 82×25 mm envelope, which keeps unbalanced forces low in fast-actuating linkages the 68 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 Omitting the inner ring frees radial space — at a 68 mm shaft the outer diameter is only 82 mm and the width 25 mm, yet C is 49.5 kN The thin 7.0 mm section makes the 241 g bearing sensitive to seat geometry — a tapered or lobed journal preloads part of the needle set and shows up as local pitting 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 68×82×25 mm envelope. Typical applications include motorcycle and light-vehicle transmissions, connecting-rod small ends and two-stroke and compressor piston pins, where the 82 mm outside diameter and 49.5 kN dynamic rating match the duty. In motorcycle and light-vehicle transmissions the unit fits a compact 68 mm seat, and in connecting-rod small ends the 241 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 89 kN static rating. Keep the specified radial clearance; an oversized shaft or heavy interference removes it and the needles bind hot immediately. Needle bearings are pure-radial units — any thrust must be taken by separate washers or an adjacent bearing, especially on flangeless RNAO/NAO.

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.
• Needle bearings are pure-radial units — any thrust must be taken by separate washers or an adjacent bearing, especially on flangeless RNAO/NAO.
• 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.