NK50-25-TV-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 NK50-25-TV-XL model number is decoded

envelope 50×62×25 mm: 50 mm seat is the hardened and ground shaft journal itself — there is no inner ring, with a thin 6.0 mm radial section packed with small-diameter needle rollers C is 48.5 kN and C0 87 kN at the 50 mm seat; the C/C0 ratio of 0.56 is characteristic of a needle bearing — high static rating relative to dynamic in a compact 62 mm outside diameter the fatigue load limit Cur is 15 kN, the limiting speed 9,200 r/min and the thermal reference speed 5,400 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 0.97 kN/mm and per millimetre of width 1.94 kN/mm — the reason 25 mm-wide needle bearings routinely replace much larger ball or roller positions mass is 146 g, just 0.09 g per mm² of projected 62×25 mm envelope, which keeps unbalanced forces low in fast-actuating linkages 50 mm bore marks the medium range: mounting forces and fits become critical, and the 146 g mass calls for proper induction or press tooling rather than hand fitting The thin 6.0 mm section makes the 146 g bearing sensitive to seat geometry — a tapered or lobed journal preloads part of the needle set and shows up as local pitting 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 15 kN Cur value. The -TV suffix specifies a glass-fibre reinforced polyamide 66 window-type cage; it spaces the rollers for low friction and is the reason the limiting speed can reach 9,200 r/min. Typical applications include connecting-rod small ends, textile machine heald and cam shafts and motorcycle and light-vehicle transmissions, where the 62 mm outside diameter and 48.5 kN dynamic rating match the duty. In connecting-rod small ends the unit fits a compact 50 mm seat, and in textile machine heald and cam shafts the 146 g mass keeps unbalanced forces low in fast linkages. Designers also specify it for motorcycle and light-vehicle transmissions, relying on the 25 mm width and the published 87 kN static rating. Keep the specified radial clearance; an oversized shaft or heavy interference removes it and the needles bind hot immediately. 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.

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.
• 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.
• 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.