RNAO40X55X40-ZW-ASR1-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 RNAO40X55X40-ZW-ASR1-XL model number is decoded

envelope 40×55×40 mm: 40 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 70 kN and C0 118 kN at the 40 mm seat; the C/C0 ratio of 0.59 is characteristic of a needle bearing — high static rating relative to dynamic in a compact 55 mm outside diameter the fatigue load limit Cur is 19 kN, the limiting speed 11,100 r/min and the thermal reference speed 6,500 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 1.75 kN/mm and per millimetre of width 1.75 kN/mm — the reason 40 mm-wide needle bearings routinely replace much larger ball or roller positions mass is 275 g, just 0.13 g per mm² of projected 55×40 mm envelope, which keeps unbalanced forces low in fast-actuating linkages 40 mm bore marks the medium range: mounting forces and fits become critical, and the 275 g mass calls for proper induction or press tooling rather than hand fitting At 275 g the assembly is easy to drop into a connecting-rod eye, but without ribs even a small axial offset skews the needles — end float must be controlled by the surrounding parts With no ribs the rollers can be arranged very freely in the 40 mm width, giving C 70 kN at only 55 mm outside diameter — the most compact radial unit in the HR1 needle section -XL means this is an X-life bearing — Schaeffler's upgraded performance level with smoother raceways, so the 70 kN C rating and longer nominal life come without an envelope change. The -ZW double-row pack explains the high C0 of 118 kN in this thin-section bearing — two rows support the static peak that a single row could not. -ASR1 marks the outer-ring lubrication feature: the annular groove distributes grease to both needle rows of the 40 mm-wide pack. Typical applications include gearbox selector and change linkages, planetary gear bearings and copying and printing machine mechanisms, where the 55 mm outside diameter and 70 kN dynamic rating match the duty. In gearbox selector and change linkages the unit fits a compact 40 mm seat, and in planetary gear bearings the 275 g mass keeps unbalanced forces low in fast linkages. Designers also specify it for copying and printing machine mechanisms, relying on the 40 mm width and the published 118 kN static rating. 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. 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

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