MRC7306DBFTAngular Contact Ball Bearing Duplex Set, 30 x 72 x 19 mm, 29 Degree Contact Angle, Back-to-Back

Product Description

What this part is

An MRC 7306 DB angular contact ball bearing set, 30 mm bore, 72 mm outside diameter, 19 mm width per bearing, supplied as a duplex arrangement mounted back-to-back. MRC is part of the SKF group. In an angular contact bearing the ball contact line runs at an angle across the raceways rather than radially, so the bearing carries thrust in one direction and radial load together, and a pair mounted opposed carries thrust both ways.

Decoding the designation

The MRC 7300 series is the medium dimension series of the angular contact programme, and the trailing 06 is the bore code, giving 30 mm. The contact angle of the MRC 7000 series is 29° in MRC’s own scheme, which is a distinct value from the 40° of an ISO 7306-B and from the 15° of a 7306-C. DB is the back-to-back duplex arrangement. The trailing F and T letters are MRC grinding and preload codes that are not part of the verified register and are carried here as searchable references rather than as specifications.

What these specs mean in practice

Contact angle is the single figure that decides how an angular contact bearing behaves: a shallower angle such as 15° favours speed and radial stiffness, a steeper 40° favours thrust capacity, and the 29° of the MRC scheme sits between the two, carrying substantially more thrust than a 15° bearing while keeping more speed capability than a 40°. Mounting the pair back-to-back sets the two contact lines diverging outward from the shaft axis, which gives a wide effective load span and high resistance to moment loads and shaft tilting — the arrangement chosen where the pair must hold a shaft square as well as locate it axially. A face-to-face pair of the same bearings converges the load lines instead and tolerates misalignment better while resisting moments less.

Quantity and configuration

Duplex set, mounted back-to-back. Open both faces, straight bore.

Fitting notes

A duplex set is ground as a unit and the two rings go onto the shaft in the orientation the grinding was made for, marked across the outer ring faces. The set is clamped through both inner rings and both outer rings together so the ground offset closes and produces the intended preload; clamping one ring of the pair alone leaves the preload unset.

Interchange guidance

The 30 x 72 x 19 mm envelope is shared by 7306-series angular contact bearings across every maker, but the contact angle differs by scheme: an ISO 7306-B is 40°, a 7306-C is 15°, an NSK 7306A is 30° and an SNFA E330-7CE1U is 15°. Those are same-envelope related sizes, not substitutions for a 29° MRC bearing, because the angle changes both the thrust rating and the stiffness of the mounted pair.