NSK7211CTYDBC7P5Angular Contact Ball Bearing Matched Pair – 55 mm ID, 100 mm OD, 21 mm Width Each, Open, 15° Contact Angle, Back-To-Back Duplex, ABEC 5

Product Description

What this part is

NSK 7211CTYDBC7P5 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. C denotes a 15° contact angle in the NSK scheme. DB denotes a duplex back-to-back matched set. P5 is ISO Class 5, equivalent to ABEC 5, which is the class printed on the carton as ABEC5.

What these specs mean in practice

A 15° contact angle favours speed and radial stiffness, carrying less thrust than the 25° and 30° grades of the same envelope. Back-to-back mounting throws the two load lines outward, which gives a wide effective bearing span and strong resistance to moment loading from an overhung tool or pulley. ABEC 5 controls bore, outside diameter and raceway runout to precision limits suited to ground spindle work.

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.

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. Oil lubrication suits this class at speed.

Interchange guidance

The FAG B7211-C-T-P5 is the same 15° angle and precision class in the same envelope. Cage material differs between makers, which changes the published speed rating.