NSK7912A5TRDULP4YSuper-Precision Angular Contact Ball Bearing Pair 60x85x13 mm 25° Contact Angle ABEC 7 Duplex Light Preload

Product Description

What this part is

An NSK 7912A5TRDULP4Y super-precision angular contact ball bearing set in the 60 x 85 x 13 mm envelope, ISO base number 71912, supplied as a universally ground duplex pair.

Decoding the designation

7912 — single-row angular contact ball bearing, ISO 719 extra-light series, 60 mm bore.
A5 — 25° contact angle in the NSK scheme.
DUL — duplex, universally ground, light preload.
P4 — ABEC 7 precision class.

What these specs mean in practice

Each bearing of the pair takes thrust in one direction only, so the two work together to locate a shaft axially. A 25° contact angle carries more thrust and gives more axial stiffness than a 15° bearing of the same envelope, and gives up some limiting speed in exchange — the reason 25° sits at loaded spindle positions and ball-screw ends. Light preload removes internal play while keeping friction torque and running temperature at the low end of the preload range. The 719 extra-light section is the thinnest of the angular contact families, which is what allows a 60 mm bore in an 85 mm housing.

Published specifications

Bore: 60 mm (2.362 in)
Outside diameter: 85 mm (3.346 in)
Width: 13 mm (0.512 in) per bearing
Total width as a pair: 26 mm (1.024 in)
Rows: 1 per bearing
Contact angle: 25°
Precision class: ABEC 7 (P4)
Preload: light
Series: ISO 719 extra light
Rolling elements: balls
Closure: open, both faces

Quantity and configuration

Sale unit is 2 pieces, one universally ground duplex pair. Universal grinding lets the pair be assembled back-to-back, face-to-face or in tandem, with the light preload established by the ground ring offset once the faces are clamped solid.

Fitting notes

The two inner rings clamp together against a square shaft shoulder and the two outer rings against a square housing shoulder; the preload only exists once both stacks are drawn fully home. Back-to-back is the stiffest arrangement and the widest effective span, face-to-face tolerates more shaft and housing misalignment, and tandem shares one-direction thrust across both bearings.

Interchange guidance

ISO envelope 71912 at 25° in a matched light-preload set — equivalents include Fafnir 3MM9312WI-CR-DUL and SKF 71912 ACD/P4ADGA. The 15° forms in this envelope, NSK 7912CTR and 71912 CD, are related sizes rather than interchanges, since the angle sets the thrust-to-speed balance. Medium and heavy preload versions of the same number are also different parts.