NK73-25-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 NK73-25-XL model number is decoded

envelope 73×90×25 mm: 73 mm seat is the hardened and ground shaft journal itself — there is no inner ring, with a thin 8.5 mm radial section packed with small-diameter needle rollers C is 60 kN and C0 100 kN at the 73 mm seat; the C/C0 ratio of 0.60 is characteristic of a needle bearing — high static rating relative to dynamic in a compact 90 mm outside diameter the fatigue load limit Cur is 17.9 kN, the limiting speed 6,300 r/min and the thermal reference speed 4,150 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 0.82 kN/mm and per millimetre of width 2.40 kN/mm — the reason 25 mm-wide needle bearings routinely replace much larger ball or roller positions mass is 302 g, just 0.13 g per mm² of projected 90×25 mm envelope, which keeps unbalanced forces low in fast-actuating linkages with a 73 mm bore this is a heavy-industrial bearing: 302 g of stiff ring and roller set, specified where rigidity matters more than speed 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 Omitting the inner ring frees radial space — at a 73 mm shaft the outer diameter is only 90 mm and the width 25 mm, yet C is 60 kN X-life status (-XL) indicates the current Schaeffler premium execution at 73 mm bore; the 100 kN C0 rating reflects the improved rolling-contact geometry. Typical applications include small electric motor accessory drives, rocker arms and valve trains and planetary gear bearings, where the 90 mm outside diameter and 60 kN dynamic rating match the duty. In small electric motor accessory drives the unit fits a compact 73 mm seat, and in rocker arms and valve trains the 302 g mass keeps unbalanced forces low in fast linkages. Designers also specify it for planetary gear bearings, relying on the 25 mm width and the published 100 kN static rating. On reciprocating duty ensure the stroke rotates the full needle set, or brinelling occurs at the same roller positions. 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

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