RHP7218CTDUMP4Super Precision Angular Contact Ball Bearing – Straight Bore, 90 mm ID, 160 mm OD, 30 mm Width, Open, 15 Degree Contact Angle, Universally Matchable, Medium Preload, Laminated Phenolic Cage, Single Bearing

Product Description

What this part is

An RHP 7218CTDUMP4 super precision angular contact ball bearing. Bore 90 mm, outside diameter 160 mm, width 30 mm. One row of balls, open on both faces, with a machined laminated phenolic cage guided on the outer ring. Ground for universal matchability at medium preload.

Decoding the designation

Three designation schemes appear on this carton and all three agree. In the RHP main scheme, 7218-C-T-DUM-P4 gives a 15° contact angle from the C, a machined laminated phenolic cage from the T, universal duplex grinding at medium preload from DUM, and ABEC 7 precision from P4. In the RHP B-series scheme, B7218-X2-TA-DUM-EP7 gives the same 15° angle from X2 and the same ABEC 7 class from EP7. The Fafnir number 2MM218WI-CR-DUM confirms the 15° angle through its 2MM prefix. The trailing -1/2PR states the sale unit: one bearing.

What these specs mean in practice

A 15° contact angle is the high-speed, lower-thrust end of the angular contact range, carrying less axial load than a 25° or 40° bearing on the same envelope in exchange for higher speed and lower heat. Medium preload sits a step above light: it raises axial and radial stiffness and holds shaft position more tightly, at the cost of a little speed capability and slightly more heat generation. Dynamic capacity is 109 kN and static capacity 98 kN, with a limiting speed of 9,500 rpm.

Quantity and configuration

One bearing. Universal grinding means any two bearings of this designation clamp together back-to-back, face-to-face or in tandem and arrive at the specified medium preload with no shims or ground spacers, so singles combine into sets as required. Being a preload-ground bearing, it carries no radial internal clearance value.

Fitting notes

The bore is straight and mounts directly onto a cylindrical shaft seat, with no taper and no adapter sleeve. Where two are paired, the ground ring faces establish the preload, so both rings are clamped solidly against the shaft shoulder and the housing abutment. Laminated phenolic cages absorb moisture and are best left in the sealed carton until fitting.

Interchange guidance

SKF 7218 CDGB/P4A matches on all counts: CD gives the same 15° angle and DGB is SKF’s medium preload class, corresponding to RHP DUM. FAG B7218-C-T-P4S-UM is the same bearing as a universal single at medium preload. Fafnir 2MM218WI-CR-DUM and Barden 218HDM cover the same envelope. The same bearing ground to light preload, marked DUL in the RHP scheme or DGA by SKF, is a related configuration with lower stiffness and higher speed capability.