Fafnir2MM9134WIDULDuplex Angular Contact Bearing Pair – 170 mm ID, 260 mm OD, 42 mm Width, Open, 15° Contact Angle, Light Preload

Product Description

What this part is

Fafnir 2MM9134WI-CR-DUL duplex super-precision angular contact ball bearing set, supplied as a matched pair. Bore 170 mm, outside diameter 260 mm, width 42 mm per bearing, 84 mm for the stacked pair. Single row each, open on both faces, machined phenolic outer-land-riding cage, 15° contact angle. The ISO equivalent is a 7034 C series bearing.

Decoding the designation

The leading 2MM sets the contact angle at 15°, and the MM prefix identifies the Fafnir super-precision spindle range built to P4S tolerances. 9134 is the Fafnir series and size code, corresponding to the ISO 7000 dimension series in size 34, so a 7034 envelope. WI denotes the super-precision angular contact construction. CR calls out the phenolic outer-land-riding cage. DU marks a duplex set of two universally ground bearings, and the trailing L sets light preload.

Quantity and configuration

Two bearings, ground as a matched duplex set. Universal grinding lets the pair be mounted back to back, face to face or in tandem, and the light preload rating is the preload the pair develops when clamped solid.

What these specs mean in practice

A 15° contact angle favours speed and radial stiffness; a 25° bearing in the same envelope carries more thrust and runs slower. Because the set arrives preloaded rather than clearance-graded, the axial and radial stiffness are fixed at manufacture and the spindle runs without play from the first revolution. An outer-land-riding phenolic cage is guided on the outer ring land, which keeps the cage stable at high speed and low in mass, suiting grease and oil-mist lubrication. P4S tolerances hold running accuracy to machine tool spindle levels.

Fitting notes

Straight cylindrical bore, mounting directly on a ground shaft seat. Both faces are open and lubrication comes from the spindle system. The two bearings are drawn up solid against each other so the ground offset on the mating faces establishes the preload. Rated limiting speed 3400 rpm.

Interchange guidance

The same-spec 15° light-preload duplex equivalent is the SKF 7034 CD/P4ADGA. The NSK 7034CTYNSULP4 matches the envelope, angle and class but carries a ball-guided polyamide cage in place of the phenolic. A 3MM9134WI set shares the envelope with a 25° contact angle, making it a related size rather than an interchange, as is a 2MM9134WI-DUM set at medium preload.