Fixed-free and duplex O / X / T layouts
Bearing arrangement
Choose locating/floating or duplex O / X / T before sizing life.
Fixed–free (locating + floating)
One bearing takes axial location; the other floats axially to allow thermal growth. Default for most shafts with moderate ΔT.
Fixed–fixed
Both ends locate axially — only for short spans or when expansion is negligible. Risk of thermal preload.
Back-to-back (O arrangement)
Angular-contact or tapered pairs with wide effective spread — good moment stiffness.
Face-to-face (X arrangement)
Narrower spread; more tolerant of misalignment than O; lower moment stiffness.
Tandem (T arrangement)
Shares axial load in one direction — pair with a locating partner for reverse thrust.
Duplex reference
Angular contact ball (40°)
Sealing: Open
Back-to-back (O) — stiff moment, resists misalignment
Combined Fr + Fa — contact angle carries axial component
Angular contact ball (40°)
Sealing: Open
Face-to-face (X) — accommodates misalignment
Combined Fr + Fa — contact angle carries axial component
Angular contact ball (40°)
Sealing: Open
Tandem (T) — shares axial load, same contact angle
Combined Fr + Fa — contact angle carries axial component
Apply an arrangement in Selection (Operating step) for duplex load split and stiffness screens.