RHP7211ETSULP4Super Precision Angular Contact Ball Bearing – 55 mm Bore, 100 mm OD, 21 mm Width, 25° Contact Angle, P4 / ABEC 7, Light Preload, Universally Matchable Single

Product Description

What this part is

RHP 7211ETSULP4 super precision angular contact ball bearing in the ISO 02 dimension series. Bore 55 mm, outside diameter 100 mm, width 21 mm. Rings and balls are carbon chrome bearing steel to SAE 52100, through hardened and heat treated for dimensional stability.

Decoding the designation

In the RHP scheme: 7 is a single row angular contact ball bearing, 2 the ISO 02 dimension series, 11 a 55 mm bore code, E a 25° contact angle, T an outer-ring-guided laminated phenolic cage, SU a universally matchable single, L light preload and P4 the precision grade. P4 is ISO Class 4, ABEC 7 and British Standard BS292 grade EP7. The carton repeats the bearing in two further schemes, B7211X3TASULEP7 in the RHP B-series and 3MM211WICRSUL in the Fafnir scheme. X3 and 3MM both denote 25°, agreeing with the E, and EP7 in the B-series string confirms the P4 grade.

What these specs mean in practice

A 25° contact angle carries more thrust and less speed than a 15° bearing in the same envelope, which suits spindle positions where axial rigidity governs. Basic dynamic radial load rating is 50.5 kN and basic static radial load rating is 38.0 kN. Limiting speed is 20 000 rev/min on oil/air lubrication and 12 400 rev/min on grease, quoted for a single bearing under spring preload; a light-preloaded back-to-back pair derates by a factor of 0.80. A light-preloaded pair develops 490 N of axial preload at an axial stiffness of 181 N/µm. The laminated phenolic cage is rated to a maximum operating temperature of 120 °C.

Quantity and configuration

One bearing. SU denotes a universally matchable single: inner and outer rings are the same width and the ring faces are ground at manufacture so that any two bearings of this designation clamp up to the light preload value back-to-back or face-to-face without custom spacers, or run in tandem sharing load equally.

Fitting notes

The high point of radial runout is marked by a burnished spot on the inner ring face and by a V line on the outer ring diameter; the V also indicates the direction of the contact angle, and aligning the marks minimises assembled runout. Shaft abutment diameter is 64 mm and the housing abutment runs 91 mm minimum to 94 mm maximum. Corner radii are 1.5 mm on the bore and 1.0 mm on the outside diameter. Effective load centre is 28.6 mm. Internal free volume is 27.8 cm³ and the lubrication jet pitch circle is 72.0 mm. For grease lubrication a fill of 30 percent of internal volume suits low and medium speeds, reducing to 20 percent above 60 percent of rated speed. A light interference fit on the shaft with a transition fit in the housing suits a locating position with a rotating inner ring.

Interchange guidance

B7211X3TASULEP7 and Fafnir 3MM211WICRSUL are the carton-printed equivalents of this exact execution. SKF 7211 ACDGA/P4A matches on envelope, 25° contact angle, phenolic cage, P4A class and light preload, the DGA suffix being SKF’s light preload grade. FAG B7211E.T.P4S-UL matches on envelope, 25° angle, laminate phenolic cage and universal light preload but is built to the tighter P4S class, so it is a related size on precision grade. The 7211C executions run a 15° contact angle in the same envelope and are a related size rather than an interchange, as are the EL, M and H preload grades.