NK20-16-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 NK20-16-XL model number is decoded

envelope 20×28×16 mm: 20 mm seat is the hardened and ground shaft journal itself — there is no inner ring, with a thin 4.0 mm radial section packed with small-diameter needle rollers C is 14.6 kN and C0 17.5 kN at the 20 mm seat; the C/C0 ratio of 0.83 is characteristic of a needle bearing — high static rating relative to dynamic in a compact 28 mm outside diameter the fatigue load limit Cur is 3.3 kN, the limiting speed 21,100 r/min and the thermal reference speed 13,200 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 0.91 kN/mm — the reason 16 mm-wide needle bearings routinely replace much larger ball or roller positions mass is 27 g, just 0.06 g per mm² of projected 28×16 mm envelope, which keeps unbalanced forces low in fast-actuating linkages the 20 mm bore falls in the small band, the workhorse size for gearbox planetary positions, hydraulic pumps and general cam and linkage duty The thin 4.0 mm section makes the 27 g bearing sensitive to seat geometry — a tapered or lobed journal preloads part of the needle set and shows up as local pitting The hardness requirement is unforgiving: below about 58 HRC the 20 mm journal brinels under the 17.5 kN static rating, and roughness above raceway finish accelerates roller wear As an X-life (-XL) bearing it benefits from the optimised surface finish that reduces friction and raises the fatigue strength behind the 3.3 kN Cur value. Typical applications include two-stroke and compressor piston pins, motorcycle and light-vehicle transmissions and rocker arms and valve trains, where the 28 mm outside diameter and 14.6 kN dynamic rating match the duty. In two-stroke and compressor piston pins the unit fits a compact 20 mm seat, and in motorcycle and light-vehicle transmissions the 27 g mass keeps unbalanced forces low in fast linkages. Designers also specify it for rocker arms and valve trains, relying on the 16 mm width and the published 17.5 kN static rating. 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.

Typical equipment & failure modes

Selection pitfalls — read before you substitute

• 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.
• On reciprocating duty ensure the stroke rotates the full needle set, or brinelling occurs at the same roller positions.