NTNAngular Contact Ball Bearing Matched Pair – 55 mm ID, 100 mm OD, 21 mm Width Each, 42 mm Pair, Open, 15° Contact Angle, Back-to-Back, Normal Preload, ABEC 7

Product Description

What this part is

NTN 7211CDBGNP4 super-precision angular contact ball bearing, supplied as a factory matched pair. Bore Diameter: 55 mm. Outside Diameter: 100 mm. Width: 21 mm per bearing. Total Width: 42 mm across the pair. Contact Angle: 15°. Arrangement: Back-to-back (DB). Preload: Normal (GN). Precision Class: P4 (ABEC 7). Closure Type: Open. Rolling Elements: Steel balls. Material: High carbon chrome steel.

Decoding the designation

72 — the 72 dimension series, light section. 11 — bore code for a 55 mm bore. C — 15° contact angle in the NTN scheme. DB — back-to-back duplex arrangement. GN — normal preload on the NTN ladder of GL light, GN normal, GM medium and GH heavy. P4 — ISO class 4 precision, equivalent to ABEC 7.

What these specs mean in practice

Contact Angle: 15°. A 15° contact angle favours speed and radial stiffness. Back-to-back mounting places the load lines diverging outward, which gives a wide effective bearing spread and high moment rigidity. The pair carries axial load in both directions. Normal preload holds the balls in contact with both raceways through the speed range for stable running accuracy. Basic Dynamic Load Rating: 53.0 kN per bearing. Basic Static Load Rating: 40.0 kN per bearing. Basic Dynamic Load Rating: 86 kN per pair. Basic Static Load Rating: 80 kN per pair. Limiting Speed: 11,400 rpm on grease. Limiting Speed: 14,700 rpm on oil. Load Centre: 20.9 mm per bearing. Operating Temperature: −40 °C to 120 °C. Weight: 0.590 kg per bearing.

Mounting data

Shaft Shoulder Diameter da: 63.5 mm minimum. Shaft Shoulder Diameter db: 60.5 mm minimum. Housing Shoulder Diameter Da: 91.5 mm maximum. Housing Shoulder Diameter Db: 94.5 mm maximum. Fillet Radius r: 1.5 mm. Fillet Radius r1: 1.0 mm. Inner Ring Land Diameter d1: 69.0 mm. Outer Ring Land Diameter D2: 92.3 mm. Bore Type: Straight.

Quantity and configuration

Unit Quantity: 2 Pcs, one factory matched pair. Preload is ground into the ring faces at the factory, so the two bearings function as a set in the DB arrangement.

Interchange guidance

The same 55 x 100 x 21 mm, 15°, P4 super-precision execution is carried by SKF as the 7211 CD/P4A family, by NSK as the 7211CTRDULP4 family and by FAG as the B7211-C-T-P4S-UL family, each at matching preload and arrangement. The NTN designation is written 7211CDBGNP4, 7211C/DBGNP4, 7211 C DB GN P4 and 7211-C-DB-GN-P4.

FAQ

Contact angle: 15°.

Arrangement: back-to-back (DB) matched pair.

Preload: normal (GN).

Precision: P4, equivalent to ABEC 7.

Pieces supplied: 2, one matched pair.