Fafnir3MM9122WITUMSuper-Precision Angular Contact Bearing – 110 mm ID, 170 mm OD, 28 mm Width, Open, 25° Contact Angle, Matched Triplex Set

Product Description

What this part is

Fafnir 3MM9122WI-TUM super-precision angular contact ball bearing set. Bore: 110 mm. Outside diameter: 170 mm. Width: 28 mm per bearing. Rows per set: triplex. Contact angle: 25°. Precision Class: P4S (ABEC 7/9). Open on both faces, CR phenolic outer-land-riding cage, steel balls. Timken world part number: 7022E-T-P4S-TUM. Country of origin as recorded on this listing: United States.

Decoding the designation

3 = 25° contact angle. MM = super high precision, P4S class. 91 = extra-light dimension series. 22 = 110 mm bore. WI = angular contact with a low shoulder on the outer ring. CR = phenolic outer-land-riding cage. TU = triplex, universally matchable. M = medium preload. ISO equivalent: 7022E. Searchable forms: 3MM9122WI-TUM, 3MM9122WITUM, 3MM9122WICRTUM, 3MM 9122 WI CR TUM, 7022E-T-P4S-TUM.

What these specs mean in practice

A 25° contact angle carries more thrust than the 15° execution of the same envelope and runs at a lower speed ceiling. The phenolic cage rides the low outer-ring land, which keeps it stable through rapid acceleration and reversal and keeps mass and friction low. P4S is a tighter grade than P4, holding bore and outer-ring runout closer for lower spindle vibration. Medium preload raises stiffness over the light-preload build and lifts the grease-lubricated speed ceiling to 7,400 rpm.

Load ratings and speed

Dynamic radial load rating C1, ISO, per row: 94,100 N (21,200 lbf). Dynamic radial load rating C1 at one million revolutions: 103,200 N (23,200 lbf). Static radial load rating C0: 97,400 N (21,900 lbf). Limiting speed: 7,400 rpm on grease and 13,600 rpm on oil. Figures as published by Timken.

Quantity and configuration

Three pieces ship, matching the TUM triplex designation and Timken’s own rows-per-set value of triplex. Total width across the mounted stack: 84 mm. Rings are universally ground, so the three bearings stack in tandem or as a duplex pair plus a third bearing in whichever arrangement the spindle calls for, at the factory-set medium preload.

Fitting notes

Shaft backing shoulder diameter: 122.3 mm. Housing backing shoulder diameter: 158.4 mm. Maximum shaft fillet radius: 2 mm. Outer ring to-clear radius: 2.0 mm. As a preloaded matched set the bearings carry no running clearance, so the internal clearance field reads N/A. The phenolic cage sets the operating temperature ceiling at 120 °C.

Interchange guidance

Direct equivalents at the same 25° angle and medium preload: SKF 7022 ACD/P4ADGB, NSK 7022A5TRTUMP4, RHP 7022A5TRTUMP4, FAG B7022E.T.P4S.TUM. Related size: 2MM9122WI shares the 110 x 170 x 28 mm envelope at a 15° contact angle, and 3MM9122WI-TUL is the same set at light preload. Both are different parts rather than substitutions.