RHP7208CTDUHP4Super-Precision Angular Contact Ball Bearing – Straight Bore, 40 mm ID, 80 mm OD, 18 mm Width, Open, 15° Contact Angle, Heavy Preload, Universally Matchable Duplex Pair, 2 Pcs.

Product Description

What this part is

An RHP 7208CTDUHP4 super-precision angular contact ball bearing, supplied as a universally matchable duplex pair. Bore 40 mm, outside diameter 80 mm, width 18 mm per bearing, giving a 36 mm total width across the mounted pair. Single row of balls per bearing, open on both faces, with a fabric-base phenolic laminate cage. RHP is the British super-precision line now part of NSK.

Decoding the designation

Reading the RHP scheme, 7208 is the ISO 72 dimension series at a 40 mm bore, C is a 15° contact angle, T is the phenolic laminate cage, DU marks the bearing as duplex and universally ground, H sets heavy preload, and P4 is precision class ABEC 7. The same carton carries the Fafnir designation 2MM208 WI CR DUH, where 2MM is 15°, CR is the phenolic outer-land-riding cage and DUH is the duplex heavy-preload arrangement — three independent confirmations of the same specification.

What these specs mean in practice

A 15° contact angle favours speed and radial stiffness over thrust capacity; a 25° bearing in the same envelope carries more axial load and runs slower. Heavy preload raises axial and radial stiffness and improves running accuracy under load, at the cost of higher friction, more heat and a lower permissible speed than a light-preload set of the same size. The phenolic laminate cage is light, self-lubricating and quiet at speed, and is the usual choice for grease-lubricated machine tool spindles.

Quantity and configuration

Two bearings, supplied as a duplex pair. Universally ground faces let the pair be arranged back-to-back, face-to-face or in tandem, with the ground offsets producing the specified heavy preload when the rings are clamped. Because the bearings are preloaded rather than clearance-set, radial internal clearance does not apply to this configuration.

Fitting notes

Preload is established by clamping the ground ring faces solid; no shim stack or spacer is required with universally matchable rings. Shaft and housing seats to ISO 4 or better preserve the running accuracy the P4 class buys. Grease fill for a preloaded phenolic-caged spindle bearing is typically 15 to 20 percent of free space.

Interchange guidance

Direct 15° phenolic-caged duplex equivalents include the FAG B7208-C-T-P4S-DUH and the Timken/Fafnir 2MM208WICRDUH. The SKF 7208 CD/P4ADGC and NSK 7208CTYNDUHP4 share the 15° angle and the 40 x 80 x 18 mm envelope; the NSK carries a polyamide cage rather than phenolic. A 7208 ACD, 2MM208WI or 7208A5 in the same envelope is a 25° bearing and a related size, not a substitution.