NSK7905A5TYSULP4Super Precision Angular Contact Ball Bearing – 25 mm ID, 42 mm OD, 9 mm Width, Open, 25°, Light Preload, P4

Product Description

What this part is

NSK 7905A5TYSULP4 super precision angular contact ball bearing. Series: 79 (ISO 71905). Bore: 25 mm. Outside diameter: 42 mm. Width: 9 mm. Contact angle: 25°. Closure: open. Cage type: ball-guided. Tolerance class: P4, ISO Class 4, ABEC 7. Execution: single universally ground with light preload.

Decoding the designation

7905: 79-series super precision angular contact ball bearing, 25 mm bore, equivalent to ISO 71905. A5: 25° contact angle. TY: ball-guided cage. SUL: single universal grinding, light preload. P4: ISO Class 4 tolerance, ABEC 7.

Load ratings and rigidity

Basic dynamic load rating Cr: 9.35 kN. Basic static load rating C0r: 5.15 kN. Permissible axial load Pa: 4.40 kN. Effective load centre a: 12.3 mm. Mass: 0.043 kg. Preload and axial rigidity in a DB or DF pair: EL 38 N / 57 N per µm, L 70 N / 71 N per µm, M 153 N / 96 N per µm, H 290 N / 124 N per µm. Recommended grease quantity: 0.25 g per bearing.

What these specs mean in practice

A 25° contact angle carries more thrust and runs slower than the 15° C execution on the same 25 x 42 x 9 mm envelope. Light preload at 70 N gives 71 N per µm of axial rigidity in a duplex pair, which holds spindle position under cutting load while keeping heat generation low. P4 tolerance holds radial and axial runout to ABEC 7 limits, so runout stacks predictably in a multi-bearing spindle. The 79 series is the extra-light section, which is what allows the small 9 mm width in a 25 mm bore.

Fitting notes

Shaft abutment diameter da: 27.5 mm minimum. Housing abutment diameter Da: 39.5 mm maximum, Db: 40.8 mm maximum. Chamfer dimensions r 0.3 mm minimum, r1 0.15 mm minimum. Permissible shaft or housing fillet radius ra: 0.3 mm maximum, rb: 0.15 mm maximum. Universal grinding lets any number of these bearings be stacked in DB, DF or DT without spacers, each junction taking up the light preload.

Quantity and configuration

One bearing, single universally ground. Country of origin: Japan.

Interchange guidance

SKF 71905 ACD/P4ADGA and FAG B71905-E-T-P4S-UL are same-spec 25° light-preload universal equivalents. Fafnir 3MM9305WI-CR-SUL is the same part in Timken nomenclature. Searchable forms: 7905A5TYSULP4, 7905 A5 TY SUL P4, 7905-A5-TY-SUL-P4, 71905, 71905ACD, B71905E.