NSK7211CTRSUMP4YSuper-Precision Angular Contact Spindle Bearing, 55x100x21 mm, 15° Contact Angle, Universally Ground Single, Medium Preload, ABEC 7 (P4)

Product Description

What this part is:

A single super-precision angular contact ball bearing in the 55 mm bore x 100 mm outside diameter x 21 mm width envelope, the ISO 7211 size. Bore Diameter: 55 mm. Outside Diameter: 100 mm. Width: 21 mm. Contact Angle: 15°. Preload: Medium (M). Precision Rating: P4 (ABEC 7). Closure Type: Open. Number Of Rows: 1. Unit Quantity: 1 Pc.

Decoding the designation:

7211 — ISO size 7211, 55 x 100 x 21 mm.

C — 15° contact angle.

TR — NSK cage designation.

SUM — single universal medium preload. The original NSK carton is marked DUM, duplex universal medium preload, a factory-matched pair; this piece is one bearing from such a set.

P4Y — P4 precision, equivalent to ABEC 7.

What these specs mean in practice:

Medium preload gives more axial rigidity and tighter shaft location than light preload, with less heat generation at speed than heavy preload. A 15° contact angle favours speed and radial capacity over pure thrust. P4 accuracy holds low runout for machine-tool spindles, precision grinders, high-speed motion control and instrument spindles.

Mounting data:

Universally ground rings. Mounting arrangements: single, back-to-back (DB), face-to-face (DF) or tandem (DT) with another universally ground bearing of the same designation and preload class. The specified preload is reached with no shimming or custom grinding.

Quantity and configuration:

One bearing. 1 Pc.

Interchange guidance:

7211CTRSUMP4Y, 7211CTRDUMP4Y and 7211C identify the same size and class. Timken 2MM211WI, FAG B7211-C-T-P4S and SKF 7211 CD/P4A share the 55 x 100 x 21 mm 15° super-precision envelope.

Frequently asked questions:

What does SUM mean?

Single universal medium preload.

What does DUM mean?

Duplex universal medium preload, the designation of the matched pair.