Timken5305MFFDouble-Row Angular Contact Ball Bearing, Sealed, 25 x 62 x 25.4 mm, 30 Degree Contact Angle, C3 Clearance

Product Description

What this part is

The 5305MFF is a double-row angular contact ball bearing, 25 mm bore x 62 mm outside diameter x 25.4 mm (1 in) wide – the 3305 envelope.

Why a double-row angular contact instead of two single bearings:
the two ball rows sit on a single one-piece inner ring and a single one-piece outer ring, effectively a back-to-back pair built into one part. That gives you radial capacity plus thrust capacity in BOTH directions, and enough moment stiffness to hold a shaft square, all inside one bearing width. It replaces a duplex pair while taking less axial space and removing the risk of a fitter assembling the pair the wrong way round.

Contact angle is 30 degrees. This is the number to check before substituting, because it is brand-specific: MRC’s 5300 series runs a 30 degree contact angle, while the Fafnir/Timken 5300 series of the same 25 x 62 x 25.4 mm envelope runs 20 degrees. A steeper angle means more thrust capacity and more axial stiffness, at the cost of a lower speed ceiling and less radial capacity. So a Fafnir 5305K and this MRC 5305MFF will both physically fit the same housing and shaft, but they are not the same bearing in duty. Match the angle to the load, not just the dimensions.

Suffix decode

5305 is the double-row angular contact medium series with bore code 05 = 25 mm. The FF denotes the double-sealed closure – MRC’s 5300 family runs F for the single-seal form and FF for seals on both sides, and the photographs show a dark elastomer seal on the visible face. Seals make this a fit-and-forget bearing that keeps its own grease and excludes dust and splash, which is what you want on a fan, pump or agricultural drive. The cost is seal drag and a lower speed limit than the open 5305 or the snap-ring G variants, so it is not the part for a high-speed spindle.

The carton confirms the rest of the build: steel cage, C3 internal clearance and ABEC-1 (normal) precision. C3 is deliberately looser than standard – specify it when the inner ring will run hotter than the outer, or when an interference fit would otherwise squeeze the running clearance out of the bearing. On a hot-running pump or motor end, C3 is the correct call, not a downgrade.

MRC (Marlin Rockwell) is now part of SKF, so current replacements cross to SKF numbering. Related MRC family members on the same envelope include 5305C, 5305CF, 5305CFF, 5305CG, 5305CFFG and 5305MG – the trailing G adds a snap ring in the outer ring, which this part does not have. The ISO cross-reference for the envelope is 3305. Sold as one bearing. Also written 5305-M-FF, 5305 MFF and MRC5305MFF.