RHP7203CTDUMP4Super Precision Angular Contact Ball Bearing Matched Pair 17x40x12 mm 15° ABEC 7 Medium Preload

Product Description

What this part is

A duplex-ground matched pair of single-row super-precision angular contact ball bearings. Each bearing is 17 mm bore, 40 mm outside diameter, 12 mm width, ground to a 15° contact angle and a medium preload band. The pair clamps as one unit at 24 mm total width.

Decoding the designation

The 72 prefix and bore code 03 give ISO dimension series 72 at a 17 mm bore. In the RHP scheme C is a 15° contact angle, T a machined phenolic laminate cage, DU duplex universal grinding, M the medium preload grade, and P4 super-precision tolerances to ABEC 7 / ISO class 4. The Fafnir-scheme number 2MM203WI carried on the carton confirms the angle independently, since the 2MM prefix is 15°.

What these specs mean in practice

A 15° contact angle is the speed-biased choice in this family. The shallow load line keeps ball centrifugal and gyroscopic effects low, so a 15° pair reaches a higher limiting speed and runs cooler than a 25° pair of the same envelope, trading away axial capacity and axial stiffness to get there.

Medium preload sits between the light and heavy grades. Preload removes internal play, fixes the contact angle and makes axial position and runout repeatable; the friction it adds becomes heat, and that heat shifts the preload as the spindle warms. The M grade buys more axial and radial stiffness than L at the cost of more heat, which suits a spindle carrying real cutting load rather than one chasing maximum speed.

P4 holds bore, outside diameter, width and running accuracy to single-digit micron limits. Duplex grinding turns those tolerances into the preload itself: the ring faces are relieved by a measured amount, so clamping the pair solid produces the medium preload directly with no shimming.

Quantity and configuration

Matched pair, 2 Pcs, duplex ground as one set.

Fitting notes

The pair is assembled in the orientation its face marks indicate, most often back-to-back for moment stiffness, and the inner rings are clamped solid against one another so the ground relief sets the preload. A duplex set behaves as a single bearing, and its preload band of a few microns belongs to that specific pair. Shaft and housing seats at this class are ground and measured, typically j4 to k4 on the shaft and H5 to J5 in the housing.

Interchange guidance

B7203CTP4S is the RHP B-series form of this envelope and angle, 7203CD/P4A is the SKF-scheme equivalent, and 2MM203WI is the Fafnir designation. Same-envelope bearings differing in contact angle, preload grade or tolerance class — 7203E at 25°, the light and heavy preload sets, and P0 or P5 class variants — are related sizes rather than interchanges. A single universally ground bearing of this size is a different item, since SU pieces are not ground to this pair’s stack height.