RHP7209ETDULP4Super Precision Angular Contact Ball Bearing Duplex Pair – 45 mm ID, 85 mm OD, 19 mm Width Each, Open, 25 Degree Contact Angle, ABEC 7, Light Preload, Phenolic Cage

Product Description

What this part is

RHP 7209ETDULP4 matched duplex pair of super-precision angular contact ball bearings, 45 mm bore, 85 mm outside diameter, 19 mm width per bearing. The raceways are offset so the ball contact line runs at an angle across the bearing, which is what lets an angular contact bearing take thrust in one direction alongside its radial load.

Decoding the designation

Three designations appear on the carton and they agree with each other. 7209-E-T-DUL-P4 is the RHP form: E gives a 25° contact angle, T a fabric-base laminate phenolic cage, DUL a duplex set at light preload and P4 the ABEC 7 precision grade. B7209-X3-TA-DU-EP7 is the RHP B-series form, where X3 is again 25° and EP7 is again ABEC 7. 3MM209WI-CR-DUL is the Fafnir equivalent, where 3MM confirms 25° a third time and CR marks a phenolic outer-land-riding cage.

What these specs mean in practice

A 25° contact angle sits in the middle of the angular contact range: it carries appreciably more thrust than a 15° bearing while retaining more speed capability than a 40°. That balance is why 25° is the common choice for machine tool spindles that see both cutting thrust and high rotational speed. Light preload gives running accuracy and stiffness with the least heat generation of the preload ladder, so it suits high-speed positions where a medium or heavy setting would run the spindle hot. The phenolic cage is light, quiet and forgiving of thin oil films. Basic dynamic capacity is 33.5 kN and basic static capacity 22.5 kN, with a limiting speed of 20,000 rpm.

Preload and clearance

These bearings are preload-set rather than clearance-set. Internal geometry is fixed by the axial force applied through the ground faces when the pair is clamped, so radial internal clearance is not a parameter and no clearance class applies.

Quantity and configuration

Two bearings, supplied as a matched duplex set. Each is 19 mm wide, so a mounted pair occupies 38 mm. Universal grinding means the faces are ground so the pair can be mounted back-to-back, face-to-face or in tandem, with the light preload established on clamp-up.

Interchange guidance

The 45 × 85 × 19 mm envelope is the ISO 7209 size. The Fafnir 3MM209WI-CR-DUL marked on the carton is the same 25° light-preload pair, and SKF 7209 ACD/P4A with the DGB light-preload suffix matches the angle and preload. On SKF designations the DGA, DGB and DGC suffixes are preload classes rather than mounting arrangements, so they describe preload magnitude on a universally matchable set. A 7209C at 15° or a 7209 B at 40° occupies the same envelope but is a different bearing, because the angle changes both the thrust capacity and the speed rating.