STO40 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 STO40 model number is decoded

envelope 40×80×19.8 mm: the 80 mm outside diameter is the track-running surface — a thick-walled outer ring over a 40 mm bore — and the 19.8 mm width sets the contact width on the mating track the catalogue lists C 23.7 kN and C0 40 kN for the STO yoke-type track roller with inner ring, without axial guidance; the C/C0 ratio of 0.59 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 kN at 40 mm bore, equivalent to 0.59 kN of dynamic rating per millimetre — the limiting speed is 850 r/min and, as for HR1 track rollers, no thermal reference speed is published the 40 mm bore takes the mounting pin or shaft; across the 19.8 mm contact width the dynamic rating works out to 1.20 kN per millimetre of rolling-element complement mass is 530 g, or 0.33 g per mm² of the 80×19.8 mm track envelope — inertia that the drive must accelerate on every index of the cam the 40 mm pin bore places this bearing in the medium band, where the 80 mm envelope already carries ratings in the tens of kilonewtons C 23.7 kN and C0 40 kN already account for outer-ring bending between supports; the limiting speed is 850 r/min with no reference speed given 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 conveyor transfer and diverting stations, robotic arm linear axes and automotive welding jig rollers, where the 80 mm track diameter and 23.7 kN dynamic rating match the duty. In conveyor transfer and diverting stations the unit fits a compact 40 mm seat, and in robotic arm linear axes the 530 g mass keeps follower kinetics light. Designers also specify it for automotive welding jig rollers, relying on the 19.8 mm width and the published 40 kN static rating. The crowned outer profile tolerates only small skew; a track that departs by more than the catalogue angle still causes edge loading. Sealed PP/2RSR units are greased for life: never add a grease nipple, and respect the lower limiting speed imposed by the rubbing lips.

Typical equipment & failure modes

Selection pitfalls — read before you substitute

• The crowned outer profile tolerates only small skew; a track that departs by more than the catalogue angle still causes edge loading.
• Sealed PP/2RSR units are greased for life: never add a grease nipple, and respect the lower limiting speed imposed by the rubbing lips.
• 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.