SNR71904HVDUJ74Super-Precision Angular Contact Ball Bearing Pair 20 x 37 x 9 mm, 25° Contact Angle, P4, Light Preload, Duplex Universal

Product Description

What this part is

A matched pair of single-row super-precision angular contact ball bearings, each 20 mm bore by 37 mm outside diameter by 9 mm wide, in the 719 extremely-light dimension series. This is a machine-tool spindle bearing: high running accuracy, high speed capability, combined radial and axial load capacity.

Decoding the designation

719 — extremely light dimension series.
04 — 20 mm bore size code.
H, V — SNR super-precision high-speed execution.
DU — duplex universal: two universally ground bearings supplied as a set.
J74 — light preload in the SNR suffix scheme, equivalent to the DUL designation of the FAG and RHP schemes.
25° — contact angle, corresponding to the E designation in the FAG scheme and A5 in the NSK scheme.

What these specs mean in practice

A 25° contact angle carries more thrust and less speed than a 15° bearing of the same envelope, which makes it the choice where a spindle sees real axial cutting load rather than pure high-rpm running.

Universal grinding is what makes a duplex set arrangement-flexible: the ring faces are ground so the pair sets its intended preload in back-to-back, face-to-face or tandem stacking without spacers ground to order. Light preload favours speed and thermal headroom over axial stiffness.

Back-to-back mounting of the pair gives the widest effective load span and the most rigid resistance to overturning moments. Face-to-face is more tolerant of shaft and housing misalignment. Tandem doubles thrust capacity in one direction only.

Published specifications

Bore: 20 mm (0.7874 in)
Outside diameter: 37 mm (1.4567 in)
Width, each bearing: 9 mm (0.3543 in)
Total width, pair: 18 mm (0.7087 in)
Contact angle: 25°
Precision class: P4 (ABEC 7)
Preload: light
Rows: 1 per bearing
Closure: open, both faces
Arrangement: duplex universal, DB, DF or DT

Quantity and configuration

Two bearings, 2 Pcs, supplied as one matched duplex universal set.

Fitting notes

The shaft and housing seats are ground and held to super-precision tolerance; the accuracy of the bearing is realised only on seats held to it. The etched high-shoulder faces of the two outer rings identify the arrangement, and they go together according to the intended back-to-back, face-to-face or tandem stacking. Mounting is by controlled press or induction heat on the ring being fitted, with load never taken through the ball complement.

Interchange guidance

Genuine same-spec equivalents at 25° and P4 class: SKF 71904 ACD/P4ADGA, NSK 7904A5TRDULP4, FAG B71904-E-T-P4S-DUL, RHP 7904ETDULP4, and Timken/Fafnir 3MM9904WI-DUL. Related sizes that share the 20 x 37 x 9 mm envelope but are a different part: any 15° variant (SKF 71904 CD, FAG B71904-C, NSK 7904C), and the same bearing at medium or heavy preload (J84, DUM, DUH).