RHPSuper Precision Angular Contact Ball Bearing Duplex Pair – 120 mm ID, 215 mm OD, 40 mm Width, 25° Contact Angle, P4, Light Preload, Open

Product Description

What this part is

RHP 7224ETDULP4 super precision angular contact ball bearings, supplied as a factory matched duplex pair. Bore: 120 mm. Outside diameter: 215 mm. Width: 40 mm per bearing, 80 mm across the pair. Series: 72, ISO dimension series 02. Single row each, open, straight bore, universally faced. Manufactured in the United Kingdom.

Decoding the designation

Contact Angle: 25°. Cage: machined laminated phenolic resin, outer ring guided. Grouping: DU, paired unit. Preload: Light. Precision Grade: P4, equivalent to EP7, ABEC 7 and ISO Class 4.

What these specs mean in practice

Dynamic Load Rating: 189 kN per bearing. Static Load Rating: 184 kN per bearing. Limiting speed: 8,800 rpm on oil/air lubrication and 5,700 rpm on grease for a single bearing. A 25° contact angle carries more thrust and gives a stiffer axial response than a 15°, and runs cooler and faster than a 30° or 40°. The 72 section is heavier than the 70 section at the same 120 mm bore, 215 mm outside diameter against 180 mm and 40 mm wide against 28 mm, and that extra section carries a larger ball complement and thicker rings for higher capacity and stiffness. P4 holds tighter running accuracy, which lowers runout and vibration: inner ring radial runout 5 µm maximum, outer ring radial runout 10 µm maximum.

Preload and stiffness

Axial preload for this light-preload pair: 2,280 N. Axial stiffness at light preload: 409 N/µm. Light preload gives the lowest internal friction and heat generation of the four preload classes and the highest permissible speed. Mounted back-to-back, the recommended limiting speed for a light-preload pair is 0.80 of the single-bearing figure, giving 7,040 rpm on oil/air and 4,560 rpm on grease. Preload is set at manufacture, so no internal clearance value applies.

Quantity and configuration

Two pieces, a factory matched duplex pair. Universal face control means the inner and outer rings are the same width and the face steps are pre-adjusted, so the pair mounts back-to-back for maximum moment stiffness and two-direction thrust, face-to-face, or in tandem to double thrust capacity in one direction, all at the marked light preload and without ground spacers. The high point of radial runout is marked with a burnished spot on the inner ring face and a V line on the outer ring outside diameter.

Mounting data

Inner ring abutment diameter d1: 132 mm minimum. Outer ring abutment diameters D1 and D2: 203 mm and 208 mm maximum. Fillet radii r and r1: 2.5 mm and 1.5 mm minimum. Effective load centre a: 59.1 mm. Lubrication jet pitch circle diameter: 156.3 mm. Internal free volume: 225.7 cm3 per bearing. Maximum recommended operating temperature: 120 °C. Rings and balls: SAE 52100 through-hardened chrome bearing steel. Mass: 5.426 kg (11.96 lb) each, 10.852 kg (23.93 lb) for the pair.

Interchange guidance

Carton designations: 7224ETDULP4, 7224-E-T-DUL-P4, B-7224-E-T-DUL-P4, B7224E, 7224X4. NSK 7224A5TRDULP4 is the current-scheme equivalent at 25° with the same outer-ring-guided phenolic cage. SKF 7224 ACD/P4ADGA and FAG B7224-E-T-P4S-UL are 25° light-preload equivalents. Fafnir 3MM224WI-DUL is the 25° equivalent in the 72 envelope. Related sizes, same bore and different envelope or angle: Fafnir 3MM9124WICRDUL is the 7024 envelope at 120 x 180 x 28 mm, and 7224-C-T-DUL-P4 and Fafnir 2MM224WI are the 15° versions of this envelope.