STO50 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 STO50 model number is decoded

envelope 50×90×19.8 mm: the 90 mm outside diameter is the track-running surface — a thick-walled outer ring over a 50 mm bore — and the 19.8 mm width sets the contact width on the mating track the catalogue lists C 25.5 kN and C0 47 kN for the STO yoke-type track roller with inner ring, without axial guidance; the C/C0 ratio of 0.54 reflects a rolling-element pack sized for heavy static track loading, and the 20.0 mm radial section gives the outer ring its bending stiffness fatigue load limit Cur is 6.4 kN at 50 mm bore, equivalent to 0.51 kN of dynamic rating per millimetre — the limiting speed is 650 r/min and, as for HR1 track rollers, no thermal reference speed is published the 50 mm bore takes the mounting pin or shaft; across the 19.8 mm contact width the dynamic rating works out to 1.29 kN per millimetre of rolling-element complement mass is 617 g, or 0.35 g per mm² of the 90×19.8 mm track envelope — inertia that the drive must accelerate on every index of the cam at 50 mm pin bore this is a mainstream industrial size — conveyor drives, winches and medium gearboxes use the 19.8 mm width as a standard mounting space Reading STO: yoke roller with inner ring, no flanges; the 19.8 mm-wide unit is located laterally by housing shoulders or circlips rather than by integral ribs Because the inner ring is supplied, the mounting pin only needs standard bearing-seat tolerance and surface — hardening to raceway quality is unnecessary Typical applications include printing press sheet-transfer grippers, glass and ceramic line conveyors and cam drives and indexing tables, where the 90 mm track diameter and 25.5 kN dynamic rating match the duty. In printing press sheet-transfer grippers the unit fits a compact 50 mm seat, and in glass and ceramic line conveyors the 617 g mass keeps follower kinetics light. Designers also specify it for cam drives and indexing tables, relying on the 19.8 mm width and the published 47 kN static rating. Yoke lugs must support the pin on both sides over its full length — single-sided support turns the pin into a cantilever beam. Flangeless STO/RSTO/RNA22/NA22 rollers need external axial location; circlips or shoulders must control end float or the roller walks off the track.

Typical equipment & failure modes

Selection pitfalls — read before you substitute

• Yoke lugs must support the pin on both sides over its full length — single-sided support turns the pin into a cantilever beam.
• Flangeless STO/RSTO/RNA22/NA22 rollers need external axial location; circlips or shoulders must control end float or the roller walks off the track.
• Full-complement NATV/NUTR/PWTR rollers make heat and flat-spot easily — slow continuous rotation is fine, stationary load on a turning track is not.