NSK7910A5TRSUMP4YAngular Contact Ball Bearing – 50 mm Bore, 72 mm OD, 12 mm Wide, 25° Contact Angle, ABEC 7, Medium Preload, Phenolic Cage

Product Description

What this part is:

NSK 7910A5TRSUMP4Y super-precision angular contact ball bearing, single universally ground. Bore Diameter: 50 mm. Outside Diameter: 72 mm. Overall Width: 12 mm. Contact Angle: 25°. Precision Class: ABEC 7 / P4Y. Preload: Medium, 390 N. Cage Material: Phenolic. Cage Type: Machined, outer-ring guided. Rolling Elements: Ball. Bore Type: Straight. Closure Type: Open. Number Of Rows: 1. Item Weight: 0.13 kg (0.28 lb). Series: 19. Unit Quantity: 1 Pc.

Decoding the designation:

79 — ISO dimension series 19, the extra-thin spindle section. Same bore as a 70-series bearing in a much smaller radial envelope.

10 — bore code. Multiplied by five it gives the 50 mm bore.

A5 — 25° contact angle. The steeper of NSK’s two standard super-precision angles.

TR — laminated phenolic cage, outer-ring guided, rated to 120 °C.

SU — single universally ground. One bearing, faces adjusted so it stacks with any other SU of the same designation in any arrangement.

M — medium preload, 390 N axial for this size and angle.

P4Y — NSK’s special accuracy class, held tighter than P4 for running accuracy.

What these specs mean in practice:

Dynamic Load Rating: 15,900 N. Static Load Rating: 14,200 N. The 19-series section trades load capacity for radial envelope, which is the whole reason to specify one.

Limiting Speed: 16,300 rpm grease; 26,300 rpm oil. The oil figure assumes an oil/air system; the grease figure assumes a premium high-speed synthetic grease.

Contact Angle: 25°. Steeper than the 15° execution, so it carries more thrust and reaches a lower speed ceiling on the same envelope. The 15° 7910C on this size runs to 18,600 rpm on grease against this bearing’s 16,300.

Preload: Medium, 390 N, giving 175 N/µm of axial stiffness in a matched pair. Light preload on this size is 150 N, heavy is 780 N.

Cage Material: Phenolic. Machined laminated fabric-base phenolic, guided on the outer ring land.

Lubricant: grease or oil.

Mounting data:

Chamfer r min: 0.6 mm. Chamfer r1 min: 0.3 mm. Shaft abutment d1 min: 55 mm. Housing abutment D1 max: 67 mm, D2 max: 69.5 mm. Effective load centre a: 20.2 mm. Internal volume: 6.7 cm³. Pitch circle diameter for lubrication jets: 57.9 mm.

The high point of radial runout is marked with a burnished spot on the inner ring face and a V line on the outer diameter. Aligning those marks against the shaft and housing eccentricities minimises assembled runout, and the V line also shows which way the contact angle faces.

Quantity and configuration:

One bearing, single universally ground. Unit Quantity: 1 Pc. Mounting Arrangement: universally matchable, back-to-back, face-to-face or tandem with another bearing of the same designation.

Interchange guidance:

Closest first, 25° types in the 50 x 72 x 12 mm ISO 719 size: RHP 7910A5TRSUMP4 (NSK drawing in P4 grade rather than P4Y), FAG B71910-E-T-P4S-UL (P4S, phenolic cage, light preload), SKF 71910 ACD/P4A (P4A, light preload), NTN 7910UADG/GMP4 (P4, medium preload) and Fafnir 3MM9310WI SUM (P4S, medium preload). The 15° executions NSK 7910CTRSUMP4Y, SKF 71910 CD/P4A and Koyo HAR910C are related sizes, not substitutes, because thrust capacity and speed ceiling both move.

Searchable forms of the number: 7910A5TRSUMP4Y, 7910-A5-TR-SUM-P4Y, 7910 A5 TR SUM P4Y, 71910A5, 71910.