Fafnir2MM9307WOCRDULMatched Pair Super-Precision Angular Contact Ball Bearings, 35x55x10 mm Each, 15° Contact Angle, Light Preload, Phenolic Outer-Land-Riding Cage, P4S

Product Description

What this part is

A universally ground duplex pair of Fafnir super-precision angular contact ball bearings in the extra-thin 79 envelope, 35 mm bore by 55 mm outside diameter by 10 mm wide per bearing. Fafnir precision bearings are now part of Timken; the equivalent metric designation is 71907C-T-DUL-P4S.

Decoding the designation

2MM — Fafnir/Timken world-number prefix for a 15° contact angle. The MM prefix also implies P4S accuracy rather than plain P4, so a document calling this P4 is understating it
9307 — 79-series envelope, 35 mm bore (metric 71907)
CR — fabric-reinforced phenolic cage, riding on the outer ring land
DUL — duplex, universally ground, light preload; the pair can be mounted DF, DB or DT with no shims
WO — a Fafnir internal-execution suffix with no published decode. It is carried here as a search term and deliberately not interpreted

Correcting the source data

The previous copy claimed manufacture in the United States and listed automotive among the applications. Fafnir is an American marque, but no origin marking is documented for the item in hand, so no origin is claimed. And a 15° P4S spindle bearing is not an automotive part — the reference has been dropped so the page reaches the machine-tool buyers who actually want it.

What these specs mean in practice

Two things make this bearing worth specifying. The 79 envelope is unusually thin for its bore, so it fits spindle noses where a 70- or 72-series bearing simply will not go. And the outer-land-riding phenolic cage — the CR — is the high-speed cage: light, self-lubricating, quiet, and centrifugally stable because it is guided on the stationary outer ring rather than thrown outward by the inner. Phenolic sets a temperature ceiling in exchange. Light preload keeps heat down and the speed limit up, which is the usual choice in grinding and high-rpm milling heads.

Published ratings and mounting data

No manufacturer-published basic dynamic or static load rating could be verified for this exact designation, so none is stated rather than borrowed from a different cage or preload variant. Boundary dimensions 35 x 55 x 10 mm per bearing are the ISO 79-series values and are confirmed; a mounted pair stacks to 20 mm.

Quantity and configuration

Supplied as matched pairs. Stock is recorded as 4 on this record and it is not established whether that counts pairs or individual bearings, so no firm piece count is claimed here — ask us for a shelf count if the exact quantity matters. Do not split a universally ground pair; the light preload only exists as the set.

Interchange guidance

Metric equivalent: 71907C-T-DUL-P4S (also written 7907C T DUL P4S). Same-envelope 15° light-preload equivalents include NSK 7907CTYNDULP4, NTN 7907CGD2GLP4 (NTN GD2GL = universally ground duplex light preload) and SKF 71907 CDGA/P4A. Do not substitute a 25° bearing: in this scheme that is a 3MM prefix, and it changes spindle stiffness and speed limit.