Double row angular contact ball bearings are particularly suitable where:
Double row angular contact ball bearing –
comparison of design envelope with bearing set composed of single row angular contact ball bearings
B = total width of bearing or bearing set
Design variants
Double row angular contact ball bearings are available as:
Larger catalogue bearings and other bearing designs GL 1.
Comparable with a pair of single row angular contact ball bearings
Double row bearings correspond in their structure to a pair of single row angular contact ball bearings in an O arrangement, but they are narrower to a certain extent. They differ in the size of the contact angle α and the design of the bearing rings. Due to the manufacturing processes used, open bearings, which are also available with sealing washers or sealing shields, can have turned recesses in the outer and/or inner ring for sealing washers or sealing shields.
Extensive and versatile range of product variants
Bearings of series 38..-B(-2RSR, -2Z), 30..-B(-2RSR, -2Z), 32..-B(-2RSR, ‑2Z), 32..-BD(-2HRS), 33..-B(-2RSR, -2Z), 33..BD(-2HRS) are self-retaining. They do not have filling slots in the end faces of the bearings rings ➤ Figure. Bearings of series 32..-BD and 33..-BD have an optimised internal construction.
In design terms, double row angular contact ball bearings thus fulfil the requirements for:
Nominal contact angle α = 25° or 30°
The nominal contact angle α in B designs is 25°, in the case of the BD variant , this is 30°.
Double row angular contact ball bearing
of basic design
Fr = radial load
Fa = axial load
α = nominal contact angle
Nominal contact angle α = 35°
Angular contact ball bearings of series 32 and 33 are self-retaining. They have filling slots on one end face of the bearing ring for filling the bearings with rolling elements ➤ Figure. The nominal contact angle is α = 35°.
These series must be fitted such that the main load direction is supported by the row of balls without filling slots under axial load.
Double row angular contact ball bearing
with filling slot
Fr = radial load
Fa = axial load
α = nominal contact angle
Nominal contact angle α = 45°
In angular contact ball bearings of series 33..-DA, the inner ring is split ➤ Figure. The inner rings are not self-retaining. Filling the bearings with a large number of balls – in conjunction with the internal design of the bearing and the contact angle of 45° – allows high alternating axial loads to be supported.
The inner ring halves are matched to the particular bearing and must not be interchanged with those of other bearings of the same size.
Double row angular contact ball bearing
with split inner ring
Fr = radial load
Fa = axial load
α = nominal contact angle
Bearings of series 32..-BD and 33..-BD are X-life bearings ➤ link. These bearings exhibit considerably higher performance than standard double row angular contact ball bearings ➤ Figure. This is achieved, for example, through the modified internal construction, higher surface quality of the contact surfaces and optimised cage design, as well as through the improved quality of the steel and rolling elements.
Increased customer benefits due to X-life
The technical enhancements offer a range of advantages, such as:
Lower operating costs, higher machine availability
In conclusion, these advantages improve the overall cost-efficiency of the bearing position significantly and thus bring about a sustainable increase in the efficiency of the machine and equipment.
Suffix XL
X-life angular contact ball bearings include the suffix XL in the designation ➤ Figure, ➤ Figure and ➤ link.
Comparison of basic dynamic load rating
Cr – bearing series 33..‑BD‑XL, bore code 02 to 16, with a bearing which is not of X-life quality (33..-B)
Cr = basic dynamic load rating
Bore code
Wide application range
Due to their special technical features, double row X-life angular contact ball bearings are highly suitable for bearing arrangements in:
X-life indicates a high product performance density and thus a particularly significant benefit to the customer.
Capable of supporting axial loads in both directions and radial loads
In addition to high radial loads, double row angular contact ball bearings can also support axial forces in both directions and tilting moments ➤ Figure. They are highly suitable for bearing arrangements with rigid axial guidance.
Contact angle and axial load carrying capacity
The bearings are available with α = 25°, 30°, 35° and 45° ➤ Figure to ➤ Figure. The axial load carrying capacity increases with the size of the contact angle. In bearings without filling slots, it is the same in both directions.
The angular adjustment facility is very limited
The bearings are not suitable for the compensation of angular misalignments. In addition, misalignments induce internal forces, which not only lead to higher temperatures, but also to a reduction in the bearing rating life.
Angular contact ball bearings sealed on both sides are maintenance-free
Open bearings and bearings with seals on both sides are greased using a high quality grease. Bearings sealed on both sides are maintenance-free for many applications, i.e. they do not require relubrication.
Open bearings must be lubricated
Angular contact ball bearings without seals and with seals on one side of series 32.., 33.., 33..-DA, 32..-BD and 33..-BD are not preserved or greased. These bearings must be lubricated with oil or grease.
Compatibility with plastic cages
When using bearings with plastic cages, compatibility between the lubricant and the cage material must be ensured if synthetic oils, lubricating greases with a synthetic oil base or lubricants containing a high proportion of EP additives are used.
Observe oil change intervals
Aged oil and additives in the oil can impair the operating life of plastics at high temperatures. As a result, stipulated oil change intervals must be strictly observed.
2RS, 2RSR and 2HRS seals are contact designs
Series 38..-B, 30..-B, 32..-B and 33..-B with the suffix 2RS, 2RSR and 2HRS have lip seals in axial contact on both sides and in radial contact ➤ Table. Bearings with the suffix RS, HRS and RSR are sealed on one side with lip seals in axial and radial contact.
2Z sealing shields and 2RZ seals are non-contact designs
Bearing series with the suffix 2Z have sheet steel sealing shields on both sides. Bearings with the suffix 2RZ are fitted with rubberised gap seals on both sides.
Open bearings
In the case of unsealed bearings, sealing must be carried out by the adjacent construction. The sealing system should reliably prevent:
Limiting speeds and reference speeds in the product tables
The product tables give two speeds for most bearings:
The limiting speed nG is the kinematically permissible speed of the bearing. Even under favourable mounting and operating conditions, this value should not be exceeded without prior consultation with Schaeffler ➤ link.
The values given in the product tables are valid for oil lubrication in the case of bearings without seals or shields and for grease lubrication where bearings are supplied greased and with seals or shields.
Values for grease lubrication
For grease lubrication, 75% of the value stated in the product tables is permissible in each case.
nϑr is used to calculate nϑ
The thermal speed rating nϑr is not an application-oriented speed limit, but is a calculated ancillary value for determining the thermally safe operating speed nϑ ➤ link.
Bearings with contact seals
For bearings with contact seals, no speed ratings are defined in accordance with DIN ISO 15312:2004. As a result, only the limiting speed nG is given in the product tables for these bearings.
The Schaeffler Noise Index (SGI) has been developed as a new feature for comparing the noise level of different bearing types and series. As a result, a noise evaluation of rolling bearings can now be carried out for the first time.
The SGI value is based on the maximum permissible noise level of a bearing in accordance with internal standards, which is calculated on the basis of ISO 15242. In order that different bearing types and series can be compared, the SGI value is plotted against the basic static load rating C0.
This permits direct comparisons between bearings with the same load carrying capacity. The upper limit value is given in each of the diagrams. This means that the average noise level of the bearings is lower than illustrated in the diagram.
The Schaeffler Noise Index is an additional performance characteristic in the selection of bearings for noise-sensitive applications. The specific suitability of a bearing for an application in terms of installation space, load carrying capacity or speed limit for example, must be checked independently of this.
Schaeffler Noise Index
for double row angular contact ball bearings
SGI = Schaeffler Noise Index
C0 = basic static load rating
Limiting values
The operating temperature of the bearings is limited by:
Possible operating temperatures of double row angular contact ball bearings ➤ Table.
Permissible temperature ranges
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