MRC7108KRDTDBAngular Contact Ball Bearing Set – Straight Bore, 40 mm ID, 68 mm OD, 15 mm Section Width, Open, 15° Contact Angle, Back-to-Back Arrangement

Product Description

What this part is

MRC 7108KRDTDB precision angular contact ball bearing set. Bore: 40 mm. Outside diameter: 68 mm. Section width: 15 mm per bearing. Series: 7100K, MRC’s extra-light angular contact section. Contact Angle: 15°. Precision Class: ABEC 7. Chrome steel balls run on a phenolic cage, rings open on both faces.

Decoding the designation

Series: 7100K, angular contact, extra light. Bore code 08: 40 mm. Type R: 15° contact angle with a counterbored outer ring. DT: matched tandem execution. DB: back-to-back mounting. Searchable forms of the number include 7108KRDTDB, 7108 KR DT DB, 7108KR-DTDB and 7108KRDT.

What these specs mean in practice

A 15° contact angle favours speed and radial rigidity, which is what carries this section to a 19,000 rpm limiting speed. The counterbored outer ring gives each bearing one high shoulder, so each piece carries thrust in a single direction and the pair covers both. ABEC 7 tolerances hold running accuracy tight and keep vibration low at speed, the reason this class is specified for machine tool and instrument spindles.

Quantity and configuration

Unit Quantity: 2 Pcs. Total set width: 30 mm. Mounting Arrangement: back-to-back. Faces are flush ground so the pair seats on a common shoulder and takes up its preload on clamp-up. Preload comes from the matched grinding rather than from an internal clearance class.

Fitting notes

Bore Type: straight, 40 mm. Housing bore: 68 mm. Back-to-back mounting places the load lines divergent, which gives the stiffer moment reaction of the two duplex arrangements and tolerates shaft deflection better than face-to-face. Both rings clamp axially against square, ground abutments.

Interchange guidance

ISO base number: 7008. Same-envelope 15° ABEC 7 equivalents are SKF 7008 CD/P4A and FAG B7008-C-T-P4S-DB. A 25° or 40° bearing on the same 40 x 68 x 15 mm envelope is a related size, carrying a different thrust-to-speed balance.

Origin

Country of origin: United States.