SKF7004 ACD/P4ADGASuper-Precision Angular Contact Ball Bearing Matched Pair 20x42x12 mm, 25° Contact Angle, Light Preload, P4A

Product Description

What this part is

A matched pair of SKF super-precision single-row angular contact ball bearings in the 70-series, 7004 size: 20 mm bore, 42 mm outside diameter, 12 mm width per bearing. In inch terms that is 0.7874 in bore, 1.6535 in outside diameter, 0.4724 in width. The two bearings are universally ground for arrangement in back-to-back, face-to-face or tandem mounting, with a built-in light preload once clamped.

Decoding the designation

7004 — dimension series 70, bore code 04, giving the 20 x 42 x 12 mm envelope.
AC — 25° contact angle in SKF’s super-precision scheme.
D — high-capacity internal design.
P4A — SKF super-precision tolerance class, ABMA Class 9 running accuracy.
DGA — two bearings supplied as a universally ground matched set with light preload.

What these specs mean in practice

A 25° contact angle sits at the thrust-biased end of the spindle-bearing range. It carries substantially more axial load per row than a 15° bearing of the same envelope and holds axial stiffness better under combined load, at the cost of a lower speed ceiling and a higher preload-induced heat rise. Light preload is the setting chosen where thermal stability and speed matter more than the last increment of stiffness. The non-metallic cage is what allows the high attainable speeds; it also sets a temperature ceiling well below that of a machined bronze or steel cage.

Published ratings and mounting data

Bore d: 20 mm (0.7874 in)
Outside diameter D: 42 mm (1.6535 in)
Width B: 12 mm (0.4724 in) per bearing; 24 mm (0.9449 in) total for the pair
Contact angle: 25°
Basic dynamic load rating C: 8.32 kN (1,870 lbf) per bearing
Basic static load rating C0: 4.15 kN (933 lbf) per bearing
Attainable speed: 38,000 rpm grease, 60,000 rpm oil-air
Precision class: SKF P4A, ABMA Class 9
Cage: non-metallic
Rows: single row per bearing

Quantity and configuration

Universally ground matched pair, light preload, 2 Pcs.

Fitting notes

Universally ground rings allow the pair to be clamped back-to-back for maximum moment stiffness, face-to-face where shaft and housing expand differently, or in tandem where thrust runs in one direction only. The preload is developed by clamping the ring faces solid against square, ground abutments; shims between the pair change the resulting preload level. Non-metallic cages set the practical lubrication and temperature limits for the arrangement.

Interchange guidance

The same-spec 25° light-preload super-precision pair in this envelope appears as FAG 7004-C-T-P4S-DUL equivalents at 15° and as NSK 7004A5TYNDBLP4 at 25°; scheme letters differ between makers, so contact angle and preload are matched on the published value rather than the letter. Related sizes in the same 20 x 42 x 12 mm envelope with a different contact angle, preload grade or tolerance class — 7004-CD/P4A at 15°, 7004-ACD/P4ADGB at medium preload, single 7004-ACD/P4A — are different parts.