What this part is:

FAG B7028C.T.P4S.UL super precision angular contact ball bearing, also called a spindle bearing. Series B70, B70..-C design. Bore: 140 mm. Outside diameter: 210 mm. Width: 33 mm. Single row, open, straight bore. Searchable forms: B7028C.T.P4S.UL, B7028CTP4SUL, B-7028-C-T-P4S-UL, B7028 CT P4S UL, B7028C.

Decoding the designation:

Contact Angle: 15°. Cage Material: laminated fabric phenolic, outer-ring guided. Precision Class: P4S, FAG's own class above P4. Preload: light. Arrangement: universal single bearing, adjusted for mounting in pairs or sets. Preload force in a light-preload pair: 866 N.

What these specs mean in practice:

A 15° contact angle favours speed and radial stiffness and carries less thrust than a 25° bearing on the same envelope. Basic dynamic load rating, radial: 153 kN. Basic static load rating, radial: 114 kN. Fatigue load limit, radial: 9.1 kN. Limiting speed: 6,300 rpm on grease, 10,000 rpm on oil. Axial rigidity in light preload: 142 N/µm. P4S tolerances give closer running accuracy and lower vibration than P4.

Quantity and configuration:

One bearing. Universal design: two or more mount together back-to-back, face-to-face or in tandem, and a pair sets light preload without shims or measurement.

Fitting notes:

Diameter shaft shoulder: 152 mm. Shoulder diameter outer ring: 199 mm. Maximum recess radius: 2 mm on the shaft side, 1 mm on the housing side. Minimum chamfer dimension: 2 mm. Distance between the apexes of the pressure cones: 39.9 mm. Operating temperature range: -30 °C to 100 °C. Weight: 3.288 kg.

Interchange guidance:

Equivalents at the same 15° contact angle and super precision class: SKF 7028 CD/P4ADGA, Fafnir 2MM9128WI. A B7028E on the same envelope carries a 25° contact angle and is a related size.