NSKPrecision Angular Contact Ball Bearing Matched Back-to-Back Pair (2 Pcs), 17 x 47 x 14 mm, 30 Degree Contact Angle, ABEC-5 P5, Phenolic Cage

Product Description

What this part is

A matched back-to-back pair of NSK precision angular contact ball bearings, 17 mm bore, 47 mm outside diameter, 14 mm wide each. Both carry a 30° contact angle, are ground to ISO Class 5 (ABEC 5), and run a phenolic resin cage. The 73 dimension series is the heavy one for this bore: a 17 mm shaft in a 47 mm housing gives more thrust capacity than the 70- or 79-series bearings on the same bore, at the cost of speed.

Designation breakdown

7303 — single-row angular contact ball bearing, 03 dimension series, bore number 03 = 17 mm bore, 47 mm outside diameter, 14 mm width.

A — 30° contact angle in NSK’s scheme, which runs C = 15°, A5 = 25°, A = 30°. SKF’s AC is 25°.

T — phenolic resin cage. NSK documents T and TR as its phenolic cage options, TR being the outer-ring-guided version.

DB — back-to-back duplex arrangement, the O configuration. DF is face-to-face and DT is tandem.

P5 — ISO tolerance class 5, equivalent to ABEC 5.

+KL-22A — supplementary code printed on the carton, recorded as it appears. The carton is also marked RM-55, and the rings are stamped 7303A / 7303 / NSK / JAPAN with a hand-written set marking.

Arrangement and contact angle

In a back-to-back pair the two contact-angle lines diverge outward, so the effective load centres sit well outside the bearing faces. A DB set is stiff against moment (tilting) loads and takes thrust in both directions from a single bearing station. Face-to-face converges the load lines and tolerates misalignment better, with less moment stiffness. Tandem points both angles the same way to double one-direction thrust.

Contact Angle: 30°. A 30° angle is the high-thrust end of the range. It carries and resists more axial load than a 15° bearing and is axially stiffer, and it gives up speed and some radial rigidity in exchange.

Cage Material: phenolic resin. The phenolic cage is light, has low inertia at speed and holds oil in its pores, which helps through marginal lubrication. NSK rates its phenolic cages to 120°C.

Published ratings and mounting data

NSK publishes these figures for the 7303A envelope. Single-bearing values. Bore (d): 17 mm. Outside diameter (D): 47 mm. Width (B): 14 mm per bearing. Contact angle: 30°. Basic dynamic load rating (Cr): 17,500 N per bearing. Basic static load rating (C0r): 8,650 N per bearing. Limiting speed, single bearing: 11,000 rpm grease, 15,000 rpm oil-bath. Effective load centre (a): 16.2 mm. Shaft abutment diameter (da min.): 23 mm. Housing abutment (Da max.): 41 mm. Chamfers: r min. 1.0 mm, r1 min. 0.6 mm. Fillet ra max.: 1.0 mm. Mass: approximately 0.116 kg per bearing.

Matched back-to-back set values. Overall mounted width (2B): 28 mm. Basic dynamic load rating (Cr), pair: 28,500 N. Basic static load rating (C0r), pair: 17,300 N. Limiting speed, pair: 9,000 rpm grease, 12,000 rpm oil-bath. Load centre spacing (a0): 32.5 mm. Housing abutment Db max.: 42 mm. Fillet rb max.: 0.6 mm. Mass: approximately 0.232 kg for the pair. Tolerance class: P5 (ISO Class 5 / ABEC 5). Cage: phenolic resin. Closure: open, no seals and no shields. Rows: one per bearing.

Set composition

Two bearings, one matched DB pair, in the original NSK carton, ring-marked as a set. A matched pair is ground so the ring faces reach the designed preload when clamped solid, with no shims, ground spacers or adjustment.

Interchange guidance

Alternatives in the 17 x 47 x 14 mm envelope: FAG 7303-B-XL-TVP and 7303-B-XL-JP (standard tolerance, 40° B angle), SKF 7303 BECBP (40° angle), NTN 7303ADB, Nachi 7303ADB and NSK 7303AW / 7303AWDB (pressed-steel cage). NSK 7303A5DB is the 25° version and NSK 7303B is 40°. RHP precision bearings were absorbed into NSK, so an RHP reference in an older machine manual can point here.