RHPSuper Precision Angular Contact Ball Bearing Matched Pair 20x42x12 mm 15° ABEC 7 Light Preload

Product Description

What this part is

A duplex-ground matched pair of RHP 7004C single-row super-precision angular contact ball bearings. Bore: 20 mm. Outside Diameter: 42 mm. Overall Width: 12 mm per bearing. Total Width: 24 mm for the pair. Contact Angle: 15°. Precision Class: P4, ISO Class 4, ABEC 7, RHP class code EP7. Cage Material: laminated phenolic resin. Cage Type: machined, outer-ring guided. Closure Type: open on both faces. Rolling Elements: carbon chrome bearing steel balls. Series: RHP 70, ISO dimension series 10. Number Of Rows: 1 per bearing.

Decoding the designation

Type 7: single-row angular contact ball bearing. Dimension series 0: ISO series 10. Bore code 04: 20 mm bore. Contact angle C: 15°. Cage T: laminated phenolic resin, outer ring guided. Grouping DU: matched duplex pair, universally face-controlled. Preload L: light. Precision grade P4: ISO Class 4, ABEC 7, British Standard EP7. Two further carton designations agree: the RHP B-series B7004X2TADULEP7, in which X2 is 15° and EP7 is ABEC 7, and the Fafnir-scheme 2MM9104WI, whose 2MM prefix is 15°.

Load ratings and speed

Dynamic Load Rating (Cr): 11.1 kN. Static Load Rating (C0r): 6.55 kN. Limiting Speed, oil/air lubrication: 53,600 rev/min. Limiting Speed, grease lubrication: 33,100 rev/min. Those figures apply to a single bearing under a spring preload with the inner ring rotating. A back-to-back light-preload pair takes a 0.80 speed factor, a set of three 0.65 and a set of four 0.60. A face-to-face arrangement takes a further 50 per cent reduction. A spring-loaded tandem pair takes 0.95.

What these specs mean in practice

A 15° contact angle is the speed-biased choice in this family. The shallow load line keeps ball centrifugal and gyroscopic effects low, so a 15° pair reaches a higher limiting speed and runs cooler than a 25° pair of the same envelope, giving up axial capacity and axial stiffness in exchange.

Light preload trades stiffness for heat. Axial Preload, light grade, as a paired set: 49 N. Axial Stiffness, light grade, as a paired set: 28 N per micrometre. Preload removes internal play, fixes the contact angle and makes axial position and runout repeatable, and the friction it creates becomes heat in the rings. The L grade adds the least of it, which is why light-preload duplex sets go into fast, moderately loaded spindles and grinding heads while the M and H grades go into stiffer, slower stacks. The bearing is preload-set at manufacture rather than clearance-set.

P4 holds bore, outside diameter, width and running accuracy to single-digit micron limits. Radial runout of the assembled inner ring, Kia: 2.5 µm. Radial runout of the assembled outer ring, Kea: 5 µm. Duplex grinding converts those tolerances into the preload itself: the ring faces are relieved by a measured amount, so clamping the pair solid produces the light preload directly with no shimming.

The laminated phenolic resin cage riding on the outer ring land keeps cage inertia and ball-pocket loads low and holds an oil film well. Maximum Operating Temperature: 120 °C, set by the phenolic. Lubricant: oil/air or grease.

Quantity and configuration

Unit Quantity: 2 Pcs, supplied as one matched duplex pair, duplex ground as a set.

Thrust direction

Each bearing on its own takes thrust in one direction. Back-to-back or face-to-face, the pair takes thrust in both directions; in tandem it takes a larger load in one direction only.

Mounting data

Inner ring abutment diameter, d1 min: 25 mm. Outer ring abutment diameters: D1 max 37 mm, D2 max 39.5 mm. Chamfer dimensions: r min 0.6 mm, r1 min 0.3 mm. Effective Load Centre (a): 10.1 mm. Internal free volume: 3.1 cm³. PCD of lubrication jets: 28.2 mm. Mass: 0.069 kg per bearing, 0.138 kg per pair.

Interchange guidance

B7004X2TADULEP7 is the RHP B-series form of this envelope and angle, and 2MM9104WI is the Fafnir-scheme number for the same 15° size. NSK 7004CTRDULP4 is the current NSK-RHP catalogue designation, and FAG B7004-C-T-P4S-DUL is the equivalent Schaeffler execution. Same-envelope bearings differing in contact angle, preload grade or tolerance class — 7004A5 at 25°, the medium and heavy preload sets, and P0 or P3 class variants — are related sizes rather than interchanges. A single universally faced bearing of this size is a different item, since SU pieces are not ground to this pair’s stack height.