RHP7218ETDUMP4Super Precision Angular Contact Ball Bearing – Straight Bore, 90 mm ID, 160 mm OD, 30 mm Width, Open, 25° Contact Angle, Universal Medium Preload, ABEC 7

Product Description

What this part is

RHP 7218ETDUMP4-1/2PR is a super precision single-row angular contact ball bearing, supplied as one bearing from a universally matched medium-preload pair. Bore: 90 mm. Outside diameter: 160 mm. Width: 30 mm. Series: 7200, ISO dimension series 02. Contact Angle: 25°. Precision Class: ISO Class 4, equal to RHP P4, BS292 EP7 and ABEC 7. Searchable forms of the designation include 7218ETDUMP4, 7218ETDUMP4-1/2PR, 7218E-T-DUM-P4, 7218 E T DUM P4, 7218A5, 7218AC and B7218X3TADUMEP7.

Decoding the designation

Type: single-row angular contact ball bearing. Dimension Series: 02. Bore Code: 18, giving a 90 mm bore. Contact Angle: 25°. Cage: T, a machined laminated phenolic cage guided by the outer ring. Grouping: DU, universally matched pair. Preload: M, medium. Precision Grade: P4. Suffix: -1/2PR, one bearing.

What these specs mean in practice

A 25° contact angle carries more thrust and less speed than a 15°, which suits spindles and screw drives working against heavy axial load. Dynamic Load Rating: 117.0 kN. Static Load Rating: 100.0 kN. Medium preload sets 2,940 N of axial preload across a pair and delivers 416 N/µm of axial stiffness. P4 accuracy holds inner-ring radial runout to 5 µm and outer-ring radial runout to 7.5 µm, which lowers runout and vibration in a spindle. The laminated phenolic cage runs to 120 °C and is quiet at speed. Rings and balls are SAE 52100 chrome bearing steel, through hardened and heat treated for dimensional stability.

Speed and lubrication

Limiting speed as a back-to-back medium-preload pair: 7,080 rpm with oil/air lubrication and 4,500 rpm with grease. As a single bearing under light external load the catalogue figures are 11,800 rpm oil/air and 7,500 rpm grease. Grease fill for a low or medium speed spindle is 30% of the 95.1 cm³ internal volume, 20% above 60% of maximum speed, and 10 to 15% above 80%. Lubrication jet pitch circle diameter: 116.7 mm.

Quantity and configuration

Unit Quantity: 1 Pc, one half of a universally matched pair. Universal face control means it pairs back-to-back, face-to-face or in tandem with its mate at the medium preload value, with no ground spacers required. The high point of radial runout is marked by a burnished spot on the inner ring face and a V line on the outer diameter; the V also shows the direction of the contact angle.

Fitting notes

Effective load centre a: 44.1 mm. Abutment diameters: shaft shoulder d1 100 mm minimum, housing shoulder D1 150 mm maximum, seal counterbore D2 154 mm maximum. Fillet radii: r 2.5 mm, r1 1.0 mm. Mass: 2.206 kg. Recommended shaft fit at 90 mm is a mean interference of 3 µm; recommended housing fit at 160 mm for a locating bearing is a mean clearance of 7 µm.

Interchange guidance

Equivalents at the same envelope, 25° angle and medium preload: SKF 7218 ACDGB/P4, Fafnir 3MM218WI CR DUM, RHP B-series B7218X3TADUMEP7 and NSK 7218A5TRSUMP4. RHP 7218C is the 15° bearing in the same envelope and is a related size. NSK 7218CTYNSUMP4 is a 15° polyamide-caged bearing in the same envelope and is also a related size.