SNR7209CG1DUJ84Super-Precision Angular Contact Ball Bearing 45x85x19 mm 15 Degree ABEC 7 Duplex Universal Pair Medium Preload

Product Description

What this part is

A super-precision angular contact ball bearing in the 7209 size, supplied as a factory-matched duplex pair. Bore 45 mm, outside diameter 85 mm, width 19 mm per bearing.

Decoding the designation

7209 — ISO angular contact 72-series: 45 mm bore, 85 mm outside diameter, 19 mm width.
C — 15° contact angle in the SNR scheme.
G1 — phenolic cage.
DU — duplex universal pair.
J84 — super-precision class at medium preload. The equivalent designation in the RHP scheme is 7209-C-T-DUM-P4, which places it at ABEC 7 with a medium preload. The lighter-preload grade in the same scheme is J74.

What these specs mean in practice

A 15° contact angle is the high-speed end of the angular contact range, with less centrifugal ball loading and less heat than a 25° bearing of the same envelope and proportionally less thrust capacity. Medium preload raises axial and radial stiffness over the light grade and holds running accuracy better as load varies, at the cost of higher friction and a higher steady-state temperature. The phenolic cage is light and self-lubricating, which is what makes the cage speeds of a 15° super-precision bearing practical, and it sets a lower temperature ceiling than machined bronze.

Quantity and configuration

2 Pcs — one matched duplex pair. The set can be arranged back-to-back, face-to-face or in tandem.

Fitting notes

The preload is ground into the ring faces and is realised only when both inner rings and both outer rings are clamped solidly against their seats. Alignment marks on the outer ring faces set the intended arrangement.

Interchange guidance

Genuine same-spec equivalents: RHP 7209-C-T-DUM-P4 and Fafnir 2MM209WI-CR-DUM, both 15° medium-preload universal pairs at the same precision class. Same-envelope 7209 bearings at a 25° or 40° contact angle, or at the light J74 or a heavy preload grade, are related sizes rather than interchanges.