MRC7315DUSingle Row Angular Contact Ball Bearing, 75 x 160 x 37 mm, Heavy 73 Series, Universally Ground for Duplex Pairing

Product Description

What this part is

A single-row angular contact ball bearing, 75 mm bore, 160 mm outside diameter, 37 mm width, with ring faces ground for universal pairing. Angular contact ball bearings take radial load and thrust in one direction along a contact line inclined to the axis, which is why they are usually opposed in pairs to locate a shaft in both directions.

Reading an MRC suffix, not an industry convention

MRC nomenclature is a known trap and it is worth being explicit about it. MRC suffixes do not follow the conventions most bearing buyers carry in their heads. The clearest example is closure coding: on an MRC bearing ZZ means rubber seals, the exact opposite of the usual industry reading of ZZ as metal shields. For that reason no MRC suffix on this part is decoded from general convention. DU is read here in MRC’s own scheme as duplex universal — ring faces relieved so two bearings of this designation mount together in any of the three arrangements and reach the intended preload.

Why the brand matters to the contact angle

The 73-series base number does not fix the contact angle across manufacturers, and this is a genuine source of mismatched orders. Read in MRC’s scheme, the 73xx angular contact series is a nominal 30° bearing. The same base number relabelled from Timken production reads as a nominal 20° bearing. That is not a trivial difference: it changes axial stiffness, limiting speed and the load split in a paired mounting. The angle stated here is the MRC reading, because the outer ring in the photographs is stamped MRC 7315 and MADE IN USA and the carton is an MRC TRW box. If your machine documentation specifies a 20° bearing under a 73xx number, confirm which maker’s scheme that documentation was written against before fitting this part.

Why 73-series and not 72-series

For a given bore, the 73 series is the heavy, wide envelope, not a variant of the 72 series. At 75 mm bore, this bearing is 160 mm across and 37 mm wide, where a 7215 in the 72 series would be markedly slimmer. The larger section means bigger balls, deeper raceway shoulders and considerably more radial and thrust capacity, at the cost of a lower speed limit and more heat generation. This is a load-carrying bearing for industrial drives rather than a high-speed precision spindle bearing.

Single row, not a double-row assembly

At 75 x 160 x 37 mm, the 7315 is a single-row bearing. The width can lead buyers to assume a double-row or paired assembly; it is not. The photographs show one bearing, one row of balls, and a one-piece machined cage. The DU grind means it is ready to be paired, not that it arrives paired.

Published ratings and mounting data

SKF does not publish dynamic load rating, static load rating or limiting speed under the legacy MRC 7315DU designation in any current or reachable source; MRC’s data for this line exists only in out-of-print paper catalogues. No figure is estimated here and none is borrowed from an SKF, Timken or other-brand 7315, because contact angle differs between those schemes and a borrowed rating would be quietly wrong. The boundary dimensions above are ISO-standardised and reliable.

Quantity and configuration

One lot is one individual bearing. The stock quantity of 1 means one bearing, not a pair — despite the DU pairing suffix in the designation, which describes how the rings are ground rather than how many are supplied. If you need an opposed pair to locate a shaft in both directions, you need two.

Fitting notes

Identify the thrust face before assembly: an angular contact bearing has a high shoulder on one side of the outer ring and a low one on the other, and the thrust must be taken against the high shoulder. Fitted backwards it will fail quickly. Mount against square shoulders, use ring heating or a proper press fixture rather than driving load through the ball set, and lubricate to the machine specification before running. If pairing two of these, keep both to the same designation and preload grade — unequal preload across a pair concentrates load on one bearing.

Interchange guidance

Equivalent designation forms include 7315DU, 7315-DU, 7315 DU, 7315D, 7315 and MRC 7315DU. The obsolescence trail is MRC to TRW MRC to SKF; the carton in the photographs is an MRC TRW box from the period MRC was a TRW division. Same-envelope bearings exist as SKF 7315 BECBM, FAG 7315-B-XL-MP, NSK 7315B and NTN 7315B, but those are nominal 40° B-type or other angles depending on maker, so treat them as envelope matches and verify the contact angle and preload requirement of your position before substituting.