Angular contact bearings explained: contact angle, pairs and where they are used
An angular contact bearing carries radial and axial load together because the balls touch the rings at an angle. Here is how they work and how to order one.
A standard deep groove ball bearing is built mainly for radial load, which pushes across the shaft. Many machines also push along the shaft, with an axial load. An angular contact ball bearing is made for that case: its raceways are shaped so that the balls touch the rings at an angle, which lets the bearing carry radial and axial load together.
What the contact angle does
The contact angle is the angle of the line along which the load passes from one ring, through the ball, to the other. A larger angle means the bearing carries more axial load but runs more slowly. Common angles are 15°, 25° and 40°, and the letter that marks each one depends on the maker. For example, the B in 7205 B means a 40° contact angle.
Single row takes axial load one way only
A single-row angular contact bearing, such as the 7204 or the 7205 B, carries axial load in one direction only. If the load can come from both sides, you need a second bearing facing the other way, or a different type. This is the most important thing to know when you replace one: the bearing has a front and a back, and fitting it the wrong way round defeats its purpose.
Pairs: DB, DF and DT
Single-row bearings are often supplied as a matched pair, so that they share the load and set the end play. The letters tell you how they are arranged:
- DB (back to back): the wide faces touch. It carries axial load in both directions and resists tilting, so it suits spindles and shafts that need rigidity.
- DF (face to face): the narrow faces touch. It also carries axial load both ways, and tolerates a little misalignment better than DB.
- DT (tandem): both bearings face the same way, so they share a heavy axial load in one direction.
Always tell your supplier which arrangement you need, and buy the pair as a pair, so the two bearings are matched.
Double-row bearings
A double-row angular contact bearing, such as the 3206, is like a back-to-back pair in a single bearing, so it carries axial load in both directions in a narrower space. The 32 and 33 series are the common ones.
Four-point contact bearings
A related type, the four-point contact ball bearing (QJ series), has a split inner ring so the ball touches at four points. One bearing carries axial load in both directions, and it is usually fitted next to a radial bearing.
Where they are used
Angular contact bearings turn up in machine tool spindles, pumps, compressors, gearboxes and automotive assemblies, wherever radial and axial loads act together.
How to read the number
The first digits give the series, and the last two digits multiplied by 5 give the bore in millimetres. A 7204 has a 20 mm bore (04 × 5), the same 20 × 47 × 14 mm size as a 6204, so it fits the same shaft and housing, but it behaves very differently under axial load. The letters after the number give the contact angle, the cage and the pairing, so quote the full number from the old bearing. Our bearing number decoder explains many of them.
Can I use a deep groove bearing instead?
Only if the machine does not need the axial load carried. A deep groove bearing of the same size will fit, but it will wear out quickly where an angular contact bearing is specified.
Need angular contact bearings?
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