Industrial MRO Reference Library · Technical Reference

Angular Contact Ball Bearings

Angular contact ball bearings have raceways offset so the load passes through the balls at an angle, letting them carry combined radial and axial loads. This sheet covers contact angle codes, single and double row types and paired mounting arrangements.

Ref MRO-0007ISO 15

Draft, open for review. Check every value against the governing standard and the manufacturer’s data before use.

What it is

In an angular contact ball bearing, the inner and outer ring raceways are offset along the bearing axis. A line through the ball contact points makes an angle with the radial plane, called the contact angle. A larger contact angle carries more axial load; a smaller angle suits higher speed. A single-row bearing carries axial load in one direction only, so it is usually mounted against a second bearing. Double-row bearings carry axial load in both directions in one unit. Angular contact bearings are used in pumps, compressors, gearboxes and machine tool spindles.

How to identify

Single-row angular contact bearings in the common series are numbered 72xx and 73xx, using the same bore code as deep groove bearings. A letter suffix gives the contact angle. Double-row types are usually numbered 32xx and 33xx, or 52xx and 53xx, depending on the maker. Physically, one shoulder of the outer ring is lower than the other. The wide face is the back face. Bearings for pairing carry a universal or matched suffix. See bearing numbers decoded and the bore code chart.

Contact angle and pairing codes

Code	Meaning	Notes
C	15° contact angle	Common on precision spindle bearings
AC	25° contact angle	Common on precision bearings
A	30° contact angle on many makers' lines	Letter use varies by maker; confirm
B	40° contact angle	Common general-purpose industrial choice
DB	Back-to-back pair (O arrangement)	Stiff against tilting; axial load both ways
DF	Face-to-face pair (X arrangement)	Tolerates more misalignment than DB
DT	Tandem pair	Shares heavy axial load in one direction
Universal matchable	Can be mounted in any pair arrangement	Suffix shows preload or clearance class

Key points

Contact angle suffixes are not fully standard across makers. Cross-reference by the maker's interchange.
A single-row bearing must be installed facing the right way. Reversing it loses axial load capacity.
Matched sets are ground to work together. Do not mix bearings from different sets.
Universal matchable bearings remove the need to stock DB, DF and DT sets separately, but the preload class must still match.
Load ratings, preload values and speed limits come from the maker's catalog.

Common mistakes

Replacing a 40° bearing with a 25° bearing because the base number matched.
Installing a pair in DF when the shaft needs DB, or the reverse.
Mixing one bearing from a matched set with a new single bearing.
Substituting a deep groove ball bearing where the design relies on angular contact.

Governing standards: ISO 15 (radial bearing boundary dimensions); manufacturer catalogs for contact angle codes, arrangements and ratings.

Reference only. Verify against the current governing code or standard, the manufacturer's data and the project documents before use. Apps for Distributors disclaims liability arising from reliance on this reference.

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