BA-5 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-5 model number is decoded

For a 5 mm shaft, BA 5 is the BA miniature single-direction thrust ball bearing from SKF (bore spelled out in millimetres after BA): loose shaft washer, loose housing washer and a pressed steel ball-cage set, outline 5×12×4 mm. Three separable parts make the set: the tight-bore shaft washer that locates on the shaft, the loose-bore housing washer in its register, and the ball-cage assembly; load is purely axial and acts in one direction. BA is SKF's miniature designation: below 10 mm bore the usual two-digit code is dropped and the number after BA spells the shaft diameter in millimetres, making BA 5 a 5 mm bearing. at BA size the ball-cage assembly is a tiny stamped sheet-steel retainer delivered loose with the two washers — there is no riveted or polymer-cage variant at this scale. Envelope 5×12×4 mm (0.197×0.472×0.157 in), 3.5 mm radial section, C 0.852 kN, C0 0.965 kN, Pu 0.036 kN. reference speed 20,000 r/min (thermal) and limiting speed 28,000 r/min (mechanical), catalogue mass 2 g. Speed-ratio note for this exact unit: the reference speed is 20,000 r/min against a 28,000 r/min limiting speed, a reference-to-limit ratio of 0.71. Bore-to-OD planning: OD 12 over bore 5 is a 2.40× step for this size, and the 4 mm height gives a bore/height ratio of 1.25; use these ratios when the housing recess around the 5 mm shaft is the first constraint. At the printed limiting speed of 28,000 r/min the mean pitch diameter dm ≈ 8.5 mm implies a dn value around 238k mm·r/min; the 20,000 r/min reference speed is the thermal-planning value under catalogue load. Preload at the mechanical ceiling: repeating Fam ≈ A·(n·dm/1000)² with factor A 5.00×10^-6 at the 28,000 r/min limiting speed raises the required axial preload to about 0.28 N; the reference-speed value 0.14 N is the thermal design point. Imperial cross-check for procurement drawings: 0.197 in bore, 0.472 in OD, 0.157 in height, and the 2 g catalogue mass converts to 0.002 kg (0.1 oz). 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 5×12 mm outline occupies less than a pencil eraser yet still publishes C0 0.965 kN; select the housing recess before the screw length, because the 4 mm stack plus cover is often the tallest feature of a miniature axial stop.

Typical equipment & failure modes

Selection pitfalls — read before you substitute

• Keep the applied thrust above Fam ≈ A·(n·dm/1000)² with the printed factor A 5.00×10^-6; for BA 5 a spring preload or the rotor weight is part of the selection at light load and high speed, because unloaded balls skid rather than roll.
• A 51-series bearing reacts thrust in one direction only — reversing positions need a mirrored single-direction pair or a 52-series double-direction unit; fitting a single BA 5 against two-way load lifts the loose washer off its raceway.
• When the housing seat cannot be machined square to the 5 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 three components are separable and interchangeable within the ISO 104 size, but keep this bearing's parts together in service and never combine washers from different manufacturers or a worn washer with a new ball set.
• There is no 51xxx coded size below 10 mm bore: the BA range is the miniature entry point for pure axial location, and at 5 mm the limit loads are small enough that shaft and housing squareness, not capacity, usually governs the design.
• Ordering discipline for BA 5: the catalogue page quotes BA 5 and its 0.852/0.965 kN ratings as one exact article; bare-number substitutions from another series or brand need a fresh dimension and rating check, not a like-for-like assumption.