RHPSuper Precision Angular Contact Ball Bearing Matched Pair – Straight Bore, 50 mm ID, 72 mm OD, 12 mm Width, Open, 25° Contact Angle, Light Preload, ABEC 7

Product Description

What this part is

RHP 7910ETDULP4 matched pair of single-row super-precision angular contact ball bearings, made in the United Kingdom. Bore: 50 mm. Outside Diameter: 72 mm. Overall Width: 12 mm. Contact Angle: 25°. Precision Class: P4, equivalent to ABEC 7 and to BS292 EP7. Number Of Rows: 1 per bearing. Rolling Elements: Balls. Bearing Material: Carbon chrome bearing steel to BS970 534A99/535A99, equivalent to SAE 52100, through hardened. Series: 7900, ISO dimension series 19. RHP is an NSK brand.

Decoding the designation

Reading 7910-E-T-DUL-P4: 7 is a single-row angular contact ball bearing, 9 is ISO dimension series 19, the bore code 10 gives a 50 mm bore, E is the 25° contact angle, T is the laminated phenolic resin cage, DU marks a paired unit, L is light preload and P4 is the precision grade. The carton carries three further schemes and all of them agree on the 25° angle: the ISO form 71910 A5, where A5 is 25°; the SKF form 71910 ACD/P4ADGA, where AC is 25° and DGA is extra light preload, one grade lighter than the light preload of this pair; and the Fafnir form 3MM9310WI CR DUL, where 3MM is 25° and CR the phenolic outer-land-riding cage.

What these specs mean in practice

Dynamic Load Rating: 15.9 kN per bearing. Static Load Rating: 14.2 kN per bearing. Limiting Speed, oil-air lubrication: 26,300 rpm. Limiting Speed, grease lubrication: 16,300 rpm. Those figures are for a single bearing under light spring preload. Mounted as a back-to-back light-preload pair the limiting speeds are multiplied by 0.80, giving 21,040 rpm on oil-air and 13,040 rpm on grease. The 19 series is the thin section of the super-precision range, which is what allows a 50 mm bore inside a 72 mm housing bore.

Cage and temperature

Cage Material: Laminated phenolic resin. Cage Type: Outer-ring guided. Maximum Operating Temperature: 120 °C, the limit set by the phenolic cage. Laminated phenolic is light and damps well, and running it against the outer ring land keeps it stable at the speeds this section reaches.

Preload and stiffness

Preload: Light. Axial Preload: 150 N for the mounted pair. Axial Stiffness: 124 N/µm. Light is the grade RHP selects most often, suiting applications where loads and speeds are not extreme. RHP publishes exactly four preload grades: extra light, light, medium and heavy.

Mounting data

Bore Type: Straight. Closure Type: Open. Minimum Shaft Abutment Diameter: 55 mm. Maximum Housing Abutment Diameter: 67 mm. Maximum Outer Ring Abutment Diameter: 69.5 mm. Chamfer r min: 0.6 mm. Chamfer r1 min: 0.3 mm. Effective Load Centre a: 20.2 mm. Internal Volume: 6.7 cm³. Pitch Circle Diameter Of Lubrication Jets: 57.9 mm. The rings are universally faced, so the pair mounts back-to-back or face-to-face without altering the preload value.

Quantity and configuration

Unit Quantity: 2 Pcs. Arrangement: DU, a universally matched pair. Item Weight: 0.258 kg (0.57 lb) for the pair, 0.129 kg (0.28 lb) each. Bore and outside diameters are matched across the set and the deviation from nominal in microns is marked on each ring face.

Interchange guidance

Cross-references: FAG B71910-E-T-P4S-DUL, Fafnir 3MM9310WI CR DUL and SKF 71910 ACD/P4ADGA, which is extra light preload rather than light. The designation is also written 7910ETDULP4, 7910 E T DUL P4, 7910-E-T-DUL-P4, B7910-E-T-DUL-EP7 and 71910 A5. A 7910 at a 15° contact angle shares this 50 x 72 x 12 mm envelope but carries different ratings and speeds, so it is a related size rather than a substitution.