RHPSuper Precision Angular Contact Ball Bearing Duplex Pair – 45 mm ID, 85 mm OD, 19 mm Width Each, Open, 15 Degree Contact Angle, ABEC 9, Medium Preload, Phenolic Cage

Product Description

What this part is: RHP 7209RCTDUMP2 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 allows an angular contact bearing to take thrust in one direction alongside its radial load. Decoding the designation: Three designations appear on the carton and all three agree. 7209-R-C-T-DUM-P2 is the RHP form: C gives a 15° contact angle, T a fabric-base laminate phenolic cage, DUM a duplex set at medium preload and P2 the ABEC 9 precision grade. 7209-R-X2-TA-DUM-EP9 is the RHP B-series form, where X2 is again 15° and EP9 is again ABEC 9. 2MMV209WO-CR-DUM is the Fafnir equivalent, where 2MM confirms 15° a third time and CR marks a phenolic outer-land-riding cage. What these specs mean in practice: A 15° contact angle is the high-speed end of the angular contact range. The shallow contact line keeps ball spin and heat generation low, which is what buys the speed, and the trade is thrust capacity: a 25° or 40° bearing of the same envelope carries substantially more axial load. ABEC 9 is the tightest commonly specified running accuracy grade, so this execution belongs on a precision grinding or high-speed spindle rather than a general drive position. Medium preload sits between the light setting used for maximum speed and the heavy setting used for maximum stiffness. 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 medium preload established on clamp-up. Interchange guidance: The 45 × 85 × 19 mm envelope is the ISO 7209 size. The closest part is the Fafnir 2MMV209WO CR DUM. Other contact angles fit the same space but change thrust capacity and speed: a 7209E or 3MM209WI at 25° and a 7209B at 40°. Precision grade matters equally: a P4 or EP7 version of this number, such as SKF 7209 CD/P4, is ABEC 7, a looser grade than the ABEC 9 here.