RNAO40X50X34-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 RNAO40X50X34-ZW-ASR1-XL model number is decoded

envelope 40×50×34 mm: 40 mm seat is the hardened and ground shaft journal itself — there is no inner ring, with a thin 5.0 mm radial section packed with small-diameter needle rollers C is 41.5 kN and C0 83 kN at the 40 mm seat; the C/C0 ratio of 0.50 is characteristic of a needle bearing — high static rating relative to dynamic in a compact 50 mm outside diameter the fatigue load limit Cur is 13.1 kN, the limiting speed 11,500 r/min and the thermal reference speed 7,000 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 1.04 kN/mm and per millimetre of width 1.22 kN/mm — the reason 34 mm-wide needle bearings routinely replace much larger ball or roller positions mass is 152 g, just 0.09 g per mm² of projected 50×34 mm envelope, which keeps unbalanced forces low in fast-actuating linkages the 40 mm bore places this bearing in the medium band, where the 50 mm envelope already carries ratings in the tens of kilonewtons RNAO marks the flangeless needle bearing without inner ring: neither race carries ribs, so the 40 mm hardened shaft journal and the housing faces provide all axial guidance With no ribs the rollers can be arranged very freely in the 34 mm width, giving C 41.5 kN at only 50 mm outside diameter — the most compact radial unit in the HR1 needle section 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 40×50×34 mm envelope. Reading -ZW: two needle rows instead of one; the load is spread over the 34 mm width while the outside diameter stays a compact 50 mm. The -ASR1 suffix provides an annular groove with lubrication holes in the outer ring, fed directly from the housing side. Typical applications include two-stroke and compressor piston pins, motorcycle and light-vehicle transmissions and rocker arms and valve trains, where the 50 mm outside diameter and 41.5 kN dynamic rating match the duty. In two-stroke and compressor piston pins the unit fits a compact 40 mm seat, and in motorcycle and light-vehicle transmissions the 152 g mass keeps unbalanced forces low in fast linkages. Designers also specify it for rocker arms and valve trains, relying on the 34 mm width and the published 83 kN static rating. Open ends draw contamination directly onto the needles; specify sealed or shielded positions in dusty environments rather than relying on grease alone. Without an inner ring the shaft is the raceway: 58–64 HRC and a ground, polished journal are mandatory, not recommendations.

Typical equipment & failure modes

Selection pitfalls — read before you substitute

• Open ends draw contamination directly onto the needles; specify sealed or shielded positions in dusty environments rather than relying on grease alone.
• Without an inner ring the shaft is the raceway: 58–64 HRC and a ground, polished journal are mandatory, not recommendations.
• Needle bearings are pure-radial units — any thrust must be taken by separate washers or an adjacent bearing, especially on flangeless RNAO/NAO.