BA-8 bearing: complete specifications & equivalents

Specification table

Source: catalog reference (SKF PUB BU/P1 17000/1 EN (Oct 2018)) · extracted 2026-09-28

Parameters extracted from the official SKF Rolling Bearings catalogue (SKF PUB BU/P1 17000/1 EN (Oct 2018)); SKF® and SKF Explorer® are trademarks of AB SKF, used here for identification only — mpnbase is not an authorized SKF distributor. Boundary dimensions are ISO 15 interchangeable; current production values may differ, verify at skf.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 BA-8 model number is decoded

BA 8 is SKF's BA-series miniature single-direction thrust ball bearing for a 8 mm shaft — the BA digits give bore in millimetres directly — supplied as a shaft washer, a housing washer and a stamped sheet-steel ball-cage assembly, 8×19×7 mm. The separable set comprises a shaft washer (ground bore, tight fit on the shaft), a loose-bore housing washer and one ball-cage assembly, reacting axial force in one direction and carrying no radial load. the BA prefix marks SKF miniature thrust ball bearings for shaft diameters below 10 mm — the digits give the bore in millimetres directly, so a BA 8 fits a 8 mm shaft rather than using the two-digit bore code. BA miniatures use the standard stamped sheet-steel ball-cage assembly: two pressed steel washers retain a small ball complement, and at these dimensions the cage and washers are handled as three loose parts. Envelope 8×19×7 mm (0.315×0.748×0.276 in), 5.5 mm radial section, C 3.19 kN, C0 3.8 kN, Pu 0.143 kN. reference speed 12,000 r/min (thermal) and limiting speed 17,000 r/min (mechanical), catalogue mass 9 g. Light-load floor: Pu = 0.143 kN is the equivalent-load threshold below which the SKF adjusted-life equation credits very long life for BA 8; the number is 4 % of the 3.19 kN dynamic rating. Mass and section check: 9 g inside the 8×19×7 mm outline leaves a 5.5 mm radial section, and the 3.8 kN static rating is 1.19× the dynamic rating — plan static safety and minimum preload against those figures. Bore-to-OD planning: OD 19 over bore 8 is a 2.38× step for this size, and the 7 mm height gives a bore/height ratio of 1.14; use these ratios when the housing recess around the 8 mm shaft is the first constraint. Sizing arithmetic on the 8 mm bore: 3.19 kN C over the 5.5 mm radial section gives 0.6 kN per section millimetre, and the 7 mm stack height is 1.27× that section — proportions typical of a BA thrust section. Stack/annulus proportions: the 7 mm axial stack over the 233 mm² washer annulus gives 30.04 mm of height per annular square millimetre ×10⁻³, and at 9 g the bearing holds about 422.2 kN of C0 per kilogram. Miniature handling note: the three BA components — shaft washer, housing washer and ball-cage assembly — are supplied loose and separate on contact, so mount the unit inside its housing recess before the shaft is offered; a dropped BA set scatters washers and balls that are nearly impossible to sort by eye, and a washer fitted reversed cannot be seen from outside once the cover is on. For reference, the 8×19 mm outline occupies less than a pencil eraser yet still publishes C0 3.8 kN; select the housing recess before the screw length, because the 7 mm stack plus cover is often the tallest feature of a miniature axial stop.

Typical equipment & failure modes

Selection pitfalls — read before you substitute

• The BA 8 is a pure axial bearing: it must never be subjected to radial load — any radial force on the 8 mm shaft has to be carried by a radial bearing mounted alongside it.
• Heat the shaft washer to at most 120 °C for mounting, or press it via a sleeve on its ground bore — force applied through the housing washer or the ball set brinells the 3.19 kN track before first rotation.
• When the housing seat cannot be machined square to the 8 mm shaft, the sphered 53-series execution of this size with its U seat washer is the self-aligning counterpart of this flat BA bearing.
• The third digit grades the section: 511 light, then 512, 513 and 514 progressively taller and heavier at the same bore — select from 3.19/3.8 kN and the available 19 mm OD, never substitute a lighter series for a heavier one without rechecking C and C0.
• There is no 51xxx coded size below 10 mm bore: the BA range is the miniature entry point for pure axial location, and at 8 mm the limit loads are small enough that shaft and housing squareness, not capacity, usually governs the design.
• Catalogue ratings are SKF PUB BU/P1 17000 figures for BA 8 as the miniature ba execution; other order numbers of the BA 8 size are different products and may carry different ratings or seating geometry — always quote the full designation when purchasing.