SKF7211ACDP4AQGBSuper Precision Angular Contact Ball Bearing Matched Set of 4 – 55 mm ID, 100 mm OD, 21 mm Width, Open, 25° Contact Angle, Medium Preload, Universally Matchable

Product Description

What this part is

SKF 7211-ACD/P4AQGB super-precision angular contact ball bearings, supplied as a matched set of four. Series: 72, medium section. Bore: 55 mm. Outside Diameter: 100 mm. Width: 21 mm per bearing. Open on both faces, machined fabric-reinforced phenolic resin cage, steel balls on steel raceways. Searchable forms: 7211 ACD/P4AQGB, 7211ACDP4AQGB, 7211-ACD-P4A-QGB, 7211ACD/P4A QGB.

Decoding the designation

Contact Angle: 25°. Precision Class: P4A — ABEC 7 dimensional tolerance with running accuracy held to ABEC 9. Set size: four bearings. Preload: medium. Universally matchable grinding. Cage: machined phenolic resin, rated for continuous service to 120°C.

What these specs mean in practice

A 25° contact angle carries more thrust and less speed than a 15° bearing on the same envelope. Four rows in one bearing position give high axial and radial capacity and high stiffness for a heavily loaded spindle. Per bearing: Dynamic Load Rating 47.5 kN, Static Load Rating 36.5 kN. Medium preload raises stiffness and shaft location accuracy over light preload, and generates more heat at speed.

Quantity and configuration

Four bearings. Unit Quantity: 4 Pcs. Universally matchable: the rings are ground so any two bearings clamped face to face or back to back reach the specified medium preload, which allows the four to be built into back-to-back, face-to-face and tandem combinations. Open bearings, lubricated on installation with oil or grease.

Fitting notes

All four bearings are clamped against a common shoulder and locknut for the ground preload to take effect. The phenolic cage sets the temperature ceiling at 120°C. Preloaded bearings run without internal clearance, so shaft and housing seats are held to super-precision tolerances.

Interchange guidance

Same-specification equivalent: FAG 7211-E-T-P4S-QUM, a universally matched quadruplex set at medium preload. SKF 7211 CD/P4AQGB is a related size at a 15° contact angle. SKF 7211 ACD/P4AQGA is a related size at light preload.