RHP7209RX2TADUMEP9Super Precision Angular Contact Ball Bearing 45x85x19 mm, 15° Contact Angle, ABEC 9 / ISO Class 2, Machined Phenolic Cage, Universal Duplex Medium Preload — Complete Matched Pair

Product Description

What this part is

Two single-row super-precision angular contact ball bearings, together one complete matched duplex pair, 45 mm bore × 85 mm outside diameter × 19 mm width. Steel rings and balls. One-piece machined laminated phenolic cage centred on the outer ring. Contact angle 15°. Medium preload set at manufacture. ABEC 9 running accuracy, the top of the super-precision range and one full class above the ABEC 7 at which most spindle bearings ship.

Designation breakdown

The full marking on both cartons and both rings is 7209RX2 TADUM EP9, an older RHP designation format in which the construction code sits ahead of the contact angle. 7209: single-row angular contact ball bearing, ISO dimension series 02, bore code 09 for a 45 mm bore, 45 × 85 × 19 mm. R: construction code, published by RHP as reverse type, as against the unmarked normal type and the ceramic-ball type. X2: the legacy RHP contact angle code for 15°; RHP’s old-to-new table gives X2 = C = 15° and X3 = E = 25°. TA: one-piece, outer-ring-centred, machined laminated phenolic resin cage, distinct from plain T (machined phenolic), TNA (two-piece riveted) and TB (inner-ring centred); the modern NSK code for the same cage is TR. DU: duplex universal, a matched pair whose faces are ground for back-to-back, face-to-face or tandem installation with no spacers and no change to the preload. M: medium preload, from RHP’s classes EL, L, M and H. EP9: BS292 precision class EP9 = ABEC 9 = ISO 492 Class 2 = RHP P2.

Precision class

Precision class governs running accuracy rather than load capacity. ABEC 9 tightens radial and axial runout and bore and outside-diameter tolerances against ABEC 7, which is what a spindle holding a surface finish or a bore tolerance requires. At ABEC 9 the accuracy of the shaft and housing becomes the limiting factor, and a Class 2 bearing in a journal ground to ordinary tolerances runs to the accuracy of that journal. Where a drawing calls for EP7 or P4, this pair runs at higher accuracy than specified.

Specifications in application

The 15° contact angle favours speed and radial rigidity over thrust, the standard choice for grinding spindles and high-speed machine-tool spindles where the cutting load is mostly radial and the top speed matters. RHP rates the 15° 7209 to 28,000 rev/min on oil-air against 24,700 rev/min for the 25° version. Thrust capacity and axial stiffness are lower than those of the 25° variant.

Medium preload raises stiffness and shaft location at the cost of heat and speed headroom. RHP derates the limiting speed of a back-to-back pair by a factor of 0.60 at medium preload against 0.80 at light, and a face-to-face mounting of the same pair takes a further 50 % reduction.

The phenolic cage runs quietly and tolerates thin lubricant films better than steel or brass, which is what carries the speed ratings. The catalogue gives a maximum recommended operating temperature of 120 °C for laminated phenolic resin caged bearings.

Published ratings

Bore d: 45 mm. Outside diameter D: 85 mm. Width B: 19 mm. Dynamic load rating Cr: 41,000 N (41.0 kN) per bearing. Static load rating C0r: 28,800 N (28.8 kN) per bearing. Limiting speed, oil-air lubrication: 28,000 rev/min. Limiting speed, grease lubrication: 17,300 rev/min. Axial preload, medium class, 15°, bore code 09: 540 N per pair, with RHP’s other classes for this size at EL 125 N, L 250 N and H 1,080 N. Axial stiffness, medium class, 15°: 94 N/µm per pair. Lubricant: grease or oil. The limiting speeds are quoted for a single bearing under spring preload with a light external load, and the grease figure assumes a Klüber Isoflex NBU15-class grease.

Mounting data

Effective load centre a: 18.2 mm. Chamfer r min: 1.1 mm. Chamfer r1 min: 0.6 mm. Shaft abutment diameter d1 min: 52 mm. Housing abutment diameter D1 max: 78 mm. Housing abutment diameter D2 max: 80 mm. Internal free volume: 18.8 cm³. Lubrication jet pitch circle diameter dT: 60.2 mm. Mass: 0.407 kg per bearing, 0.814 kg per pair. Universal facing gives the same catalogue preload in a back-to-back, face-to-face or tandem arrangement, without measured face steps or custom-ground spacers.

Quantity and configuration

This listing supplies two bearings, one complete matched duplex pair. Total Width: 38 mm for the pair. Both bearings are heat-sealed in RHP’s original amber wrapping with the O.D./BORE tolerance slips attached, alongside the two original cartons. Each carton is marked HALF PAIR, RHP’s marking for one bearing forming half of a set of two, so the two cartons together are the complete DUM pair.

Interchange guidance

Translating the legacy marking into the modern scheme, code for code, gives NSK/RHP 7209CTRDUMP2: X2 to C for 15°, TA to TR for the outer-ring-guided phenolic cage, DUM unchanged, EP9 to P2. The same-envelope SKF number is 7209 CD/P4A in the standard class, and FAG’s is the 7209 C.T.P4S.UM family. The Fafnir equivalent on the same envelope at 15° is 2MM209WI DUM. RHP became part of NSK when NSK acquired the RHP group in the early 1990s; the business traded as NSK-RHP until the RHP name reverted to plain NSK in November 2000, and these bearings are still made at the former Ransome & Marles works in Newark, England. 7209CTRDUMP2 is a dimensional and functional equivalent.