MRC1907RDBAngular Contact Ball Bearing Duplex Set, 35 x 55 x 10 mm, Thin-Section 719 Series, Back-to-Back

Product Description

What this part is

An MRC 1907 R-DB angular contact ball bearing set, 35 mm bore, 55 mm outside diameter, 10 mm width per bearing, supplied as a duplex arrangement mounted back-to-back. MRC is part of the SKF group. The ball contact line runs at an angle across the raceways rather than radially, so each bearing carries thrust in one direction together with radial load, and the opposed pair carries thrust both ways.

Decoding the designation

The MRC 1900 block corresponds to the ISO 719 extra-light dimension series, and the trailing 07 is the bore code, giving 35 mm. The 35 x 55 x 10 mm envelope is therefore the ISO 71907, cross-confirmed by the 71907 and 7907 designations already carried on this size. DB is the back-to-back duplex arrangement. The R is an MRC internal design letter that is not part of the verified register and is carried here as a searchable reference rather than as a specification.

What these specs mean in practice

The 719 series is the thinnest-section angular contact series: for a 35 mm shaft it needs only a 55 mm housing bore and 10 mm of axial length, which is what makes it the choice on a machine-tool spindle nose or a compact indexing head where the surrounding structure fixes the space. The narrow section limits load capacity against a 70 or 72 series bearing on the same bore, and the compensation is speed and stiffness per unit of space. 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. Thin-section bearings of this series are handled flat and clean, and mounting force is applied through the ring being fitted rather than across the balls.

Interchange guidance

The 35 x 55 x 10 mm envelope is shared by 71907-series angular contact bearings across every maker, but the contact angle differs by scheme: a 71907 CD is 15°, a 71907 ACD is 25°, an NSK 7907A5 is 25° and an NSK 7907C is 15°. Those are same-envelope related sizes, and matching one to this bearing requires the MRC contact angle to be established first, because the angle changes both the thrust rating and the stiffness of the mounted pair.