NSK7211ATYDBC7P5Angular Contact Ball Bearing Matched Pair – Straight Bore, 55 mm ID, 100 mm OD, 21 mm Width Each, Open, 30° Contact Angle, Back-To-Back Duplex, ABEC 5

Product Description

What this part is

NSK 7211ATYDBC7P5 angular contact ball bearings supplied as a factory-matched duplex pair. Bore 55 mm, outside diameter 100 mm, width 21 mm per bearing, 42 mm across the assembled set. Straight bore, open on both faces, one row of balls per bearing.

Decoding the designation

72 is the ISO medium angular contact dimension series and 11 is the bore code, giving a 55 mm bore. A denotes a 30° contact angle in the NSK scheme, distinct from A5 which is 25°. DB denotes a duplex back-to-back matched set. P5 is ISO Class 5, equivalent to ABEC 5.

What these specs mean in practice

A 30° contact angle sits between the 15° and 40° grades: it carries appreciably more thrust than a 15° or 25° bearing of the same envelope and gives up some speed capability in return. Back-to-back mounting throws the two load lines outward, giving a wide effective bearing span and strong resistance to moment loading. ABEC 5 controls bore, outside diameter and raceway runout to precision limits.

Quantity and configuration

Two pieces, one matched duplex pair. The set is ground together so the ring faces sit solid in the back-to-back orientation and the two bearings share load as a unit, taking thrust in both directions across the pair.

Fitting notes

The stamped faces go together for back-to-back mounting. Ring faces are ground flat and square for direct abutment, so the shaft nut and housing cap are drawn fully home against the abutting faces.

Interchange guidance

The 30° grade is specific. The SKF 7211 ACD/P5 and Fafnir 3MM211WI are 25° and the FAG 7211-B-TVP-P5 is 40°, so all three are related sizes in the same envelope rather than direct substitutions. A genuine substitution carries the same 30° angle and the same ABEC 5 class.