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Double row angular contact ball bearings
 

Double row angular contact ball bearings are particularly suitable where:

 
 
  • the design envelope is not sufficient under high loads for a pair of single row angular contact ball bearings
  • high radial and axial loads are acting simultaneously
  • tilting moments must also be supported
  • a relatively rigid bearing arrangement
    Arrangement of bearings, for example locating/locating, semi-locating/semi-locating, non-locating/non-locating, or semi-locating bearings in tandem, O or X arrangement
    is required
  • the bearing arrangement
    Arrangement of bearings, for example locating/locating, semi-locating/semi-locating, non-locating/non-locating, or semi-locating bearings in tandem, O or X arrangement
    is to run quietly in addition to meeting the requirements stated above.
 
   

Figure 1
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

 

imageref_20050505227_All.gif

 
 

Bearing design

 
 

Double row angular contact ball bearings are available as:

 
   
 

Larger catalogue bearings and other bearing designs ➤ GL 1.

 
 

Bearings of basic design

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
See Seals
washers or sealing
See Seals
shields, can have turned recesses in the outer and/or inner ring for sealing
See Seals
washers or sealing
See Seals
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 2. 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:

 
 
  • supporting axial loads in both directions and high radial loads
  • low-noise running
  • versatile application.
 

Nominal contact angle
See
Operating contact angle
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°.

 
 

   

Figure 2
Double row angular contact ball bearing of basic design

Fr =  radial load
Fa =   axial load
α =  nominal contact angle

 

imageref_20050510219_All.gif

 
 

Bearings with filling slot

Nominal contact angle
See
Operating 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 3. The nominal contact angle
Angle enclosed by the contact line between the bearing and the radial plane; applies to unloaded bearings, in which the rolling elements are in stress-free contact with the raceways
is α = 35°.

 
imageref_17757187211_All.gif   These series must be fitted such that the main load direction
Effective direction of a load
is supported by the row of balls without filling slots under axial load.
 
 

   

Figure 3
Double row angular contact ball bearing with filling slot

Fr =  radial load
Fa =  axial load
α =  nominal contact angle

 

imageref_20050512139_All.gif

 
 

Bearings with split inner ring

Nominal contact angle
See
Operating contact angle
Nominal contact angle
α = 45°

 

In angular contact ball bearings of series 33..-DA, the inner ring is split ➤ Figure 4. 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
See
Operating contact angle
Nominal contact angle
of 45° – allows high alternating axial loads to be supported.

 
imageref_17757187211_All.gif   The inner ring halves are matched to the particular bearing and must not be interchanged with those of other bearings of the same size.  
 

   

Figure 4
Double row angular contact ball bearing with split inner ring

Fr =  radial load
Fa =  axial load
α =  nominal contact angle

 

imageref_20050514059_All.gif

 
 

X-life premium quality

imageref_19964530187_All.gif   Bearings of series 32..-BD and 33..-BD are X-life bearings ➤ dimension table. These bearings exhibit considerably higher performance than standard double row angular contact ball bearings ➤ Figure 5. This is achieved, for example, through the modified internal construction, higher surface quality
See DIN 55 350 part 11 and ISO 8402 for terminology and definitions.
of the contact surfaces
The effective surface is the surface which separates the object from its surrounding medium.The actual surface is the approximate image from measuring technology of the ideal geometric surface. Note: various measuring processes or measuring conditions (e.g. stylus radius) can give different actual surfaces.The geometric surface is an ideal surface whose nominal form is defined by a drawing or other technical documentation. See DIN 4760 for further details.

See
Surface protection
Surface tension
and optimised cage
The part of a rolling bearing which separates, retains and, where necessary, guides the rolling elements
design, as well as through the improved quality
See DIN 55 350 part 11 and ISO 8402 for terminology and definitions.
of the steel and rolling elements.
 
 

Advantages

 

The technical enhancements offer a range of advantages, such as:

 
 
  • a more favourable load
    Load which, for example, is to be supported at a friction point. Also strain from pressure and/or heat.

    See Contact surface
    distribution in the bearing and thus a higher dynamic load
    The term dynamic indicates that the operating condition is with the bearing rotating. This is not a variable load.
    carrying capacity of the bearings ➤ Figure 5
  • quieter running
  • running with reduced friction
    The resistance to relative movement of two bodies in contact with each other; subdivided into friction terms, friction types and friction conditions
    and greater energy efficiency
  • lower heat generation in the bearing
  • higher possible speeds
  • lower lubricant
    Gaseous, fluid, consistent, plastic or solid material for reduction of friction and wear between two friction elements.
    consumption and, consequently, longer maintenance
    Inspection, maintenance and repair of equipment and machines.
    intervals
  • a measurably longer operating life
    See Life, rating
    of the bearings
  • high operational security
  • compact, environmentally-friendly bearing arrangements.
 

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 7, ➤ Figure 8 and ➤ dimension table.

 
 

   

Figure 5
Comparison of basic dynamic load
The term dynamic indicates that the operating condition is with the bearing rotating. This is not a variable load.
rating Cr – bearing series 33..‑BD‑XL, bore code 02 to 16, with a bearing which is not of X-life quality
See DIN 55 350 part 11 and ISO 8402 for terminology and definitions.
(33..-B)

Cr =  basic dynamic load
The term dynamic indicates that the operating condition is with the bearing rotating. This is not a variable load.
rating
Symbole/00016410_mei_in_0k_0k.gif  Bore code

 

imageref_20050508299_All.gif

 
 

Areas of application

 

Due to their special technical features, double row X-life angular contact ball bearings are highly suitable for bearing arrangements in:

 
 
  • compressors
  • fluid and hydraulic pumps
  • automotive chassis and gearboxes
  • industrial gearboxes
  • agricultural vehicles
  • elevators and packaging equipment
  • heavy motorbikes
  • machine tools
  • textile machinery.
 
imageref_17757210635_All.gif   X-life indicates a high product performance density
Mass ratio of a lubricant with respect to its volume to DIN 51 757.

Usual units for solid materials (apparent density):
- gramms per cubic centimeter g/cm3

fluids:
- gramms per millilitre g/ml

gases:
- kilogrammes per cubic meter kg/cm3

Other permissible units are kg/dm3, kg/cm3, kg/l
and thus a particularly significant benefit to the customer.
 
 

Load carrying capacity

 

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
Deviation from the normal position due to load or geometrical influence

See Misalignment error
moments ➤ Figure 2. They are highly suitable for bearing arrangements with rigid axial guidance.

 

Contact angle and axial load
Force acting in the direction of the shaft.
carrying capacity

 

The bearings are available with α = 25°, 30°, 35° and 45° ➤ Figure 2 to ➤ Figure 4. The axial load
Force acting in the direction of the shaft.
carrying capacity increases with the size of the contact angle. In bearings without filling slots, it is the same in both directions.

 
 

Compensation of angular misalignments

 

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.

 
 

Lubrication

 

Angular contact ball bearings sealed on both sides are maintenance-free

 

Open bearings and bearings with seals
Elements intended to prevent the ingress of gaseous, fluid and solid materials through the gaps formed by adjacent components whilst stationary or moving.

See
Seal
Operating life
Friction
on both sides are greased using a high quality
See DIN 55 350 part 11 and ISO 8402 for terminology and definitions.
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
Elements intended to prevent the ingress of gaseous, fluid and solid materials through the gaps formed by adjacent components whilst stationary or moving.

See
Seal
Operating life
Friction
and with seals
Elements intended to prevent the ingress of gaseous, fluid and solid materials through the gaps formed by adjacent components whilst stationary or moving.

See
Seal
Operating life
Friction
on one side of series 32.., 33.., 33..-DA, 32..-BD and 33..-BD are preserved and not greased. These bearings must be lubricated with oil
Fluid lubricant with a mineral oil and/or synthetic oil base, usually with active ingredients or additives.
or grease.

 

Compatibility with plastic cages

 

When using bearings with plastic cages, compatibility between the lubricant
Gaseous, fluid, consistent, plastic or solid material for reduction of friction and wear between two friction elements.
and the cage
The part of a rolling bearing which separates, retains and, where necessary, guides the rolling elements
material must be ensured if synthetic oils, lubricating greases
Consistent grease with a mineral oil and/or synthetic oil base with thickener as well as active ingredients or additives. See DIN 51 825 part 1 for demands on greases, grease type K, operating temperature range -20 to 140°C or DIN 51 825 part 2, for grease type KT.
with a synthetic oil
Fluid lubricant with a mineral oil and/or synthetic oil base, usually with active ingredients or additives.
base or lubricants containing a high proportion of EP additives are used.

 

Observe oil change
See Lubricant change
intervals

 

Aged oil
Fluid lubricant with a mineral oil and/or synthetic oil base, usually with active ingredients or additives.
and additives
Lubricant additive to improve viscosity-temperature behaviour or pour point, prevent corrosion, oxidation or ageing or reduce wear or foaming
in the oil
Fluid lubricant with a mineral oil and/or synthetic oil base, usually with active ingredients or additives.
can impair the operating life
See Life, rating
of plastics at high temperatures. As a result, stipulated oil change
See Lubricant change
intervals must be strictly observed.

 
 

Sealing

 

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
Elements intended to prevent the ingress of gaseous, fluid and solid materials through the gaps formed by adjacent components whilst stationary or moving.

See
Seal
Operating life
Friction
in axial contact on both sides and in radial contact ➤ Table 5. Bearings with the suffix RS, HRS and RSR are sealed on one side with lip seals
Elements intended to prevent the ingress of gaseous, fluid and solid materials through the gaps formed by adjacent components whilst stationary or moving.

See
Seal
Operating life
Friction
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
See Seals
shields on both sides. Bearings with the suffix 2RZ are fitted with rubberised gap seals
Elements intended to prevent the ingress of gaseous, fluid and solid materials through the gaps formed by adjacent components whilst stationary or moving.

See
Seal
Operating life
Friction
on both sides.

 
 

In the case of unsealed bearings, sealing
See Seals
must be carried out by the adjacent construction. The sealing
See Seals
system should reliably prevent:

 
 
  • moisture and contaminants from entering the bearing
  • the egress of lubricant
    Gaseous, fluid, consistent, plastic or solid material for reduction of friction and wear between two friction elements.
    from the bearing.
 
 

Speeds

 
 

The product tables give two speeds for most bearings ➤ dimension table:

 
 
  • the kinematic limiting speed nG
  • the thermal speed rating nϑr.
 
 

Limiting speeds

imageref_17757187211_All.gif   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
Fluid lubricant with a mineral oil and/or synthetic oil base, usually with active ingredients or additives.
lubrication
Feed of fresh lubricant to friction points. Fresh lubricant mixes with used lubricant at the friction point. Lubricant feed is by means of lubrication equipment. The time period for relubrication is shorter than that for the lubricant change interval.

See
Lubrication method
Lubrication condition
Recirculating lubrication
Lubrication technology
One-off lubrication
Hydrodynamic lubrication
Lubricant change intervall
Lubricant change
Lubricant
Lubricant paste
Oil
Grease
Lubrication film
Lubrication system
in the case of bearings without seals
Elements intended to prevent the ingress of gaseous, fluid and solid materials through the gaps formed by adjacent components whilst stationary or moving.

See
Seal
Operating life
Friction
or shields and for grease
See
Lubricant
Grease cartridge
Fatty acids
lubrication
Feed of fresh lubricant to friction points. Fresh lubricant mixes with used lubricant at the friction point. Lubricant feed is by means of lubrication equipment. The time period for relubrication is shorter than that for the lubricant change interval.

See
Lubrication method
Lubrication condition
Recirculating lubrication
Lubrication technology
One-off lubrication
Hydrodynamic lubrication
Lubricant change intervall
Lubricant change
Lubricant
Lubricant paste
Oil
Grease
Lubrication film
Lubrication system
where bearings are supplied greased and with seals
Elements intended to prevent the ingress of gaseous, fluid and solid materials through the gaps formed by adjacent components whilst stationary or moving.

See
Seal
Operating life
Friction
or shields.
 

Values for grease
See
Lubricant
Grease cartridge
Fatty acids
lubrication

 

For grease
See
Lubricant
Grease cartridge
Fatty acids
lubrication, 75% of the value stated in the product tables is permissible in each case.

 
 

Reference speeds

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 reference speeds 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.

 
 

Noise

 
 

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.

 
 

Schaeffler Noise Index

 

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
Load which, for example, is to be supported at a friction point. Also strain from pressure and/or heat.

See Contact surface
rating C0.

 
 

This permits direct comparisons between bearings with the same load
Load which, for example, is to be supported at a friction point. Also strain from pressure and/or heat.

See Contact surface
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.

 
imageref_17757187211_All.gif   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
Load which, for example, is to be supported at a friction point. Also strain from pressure and/or heat.

See Contact surface
carrying capacity or speed limit for example, must be checked independently of this.
 
 

   

Figure 6
Schaeffler Noise Index for double row angular contact ball bearings

SGI =  Schaeffler Noise Index
C0 =  basic static load
Load which, for example, is to be supported at a friction point. Also strain from pressure and/or heat.

See Contact surface
rating

 

imageref_23598378635_All.gif

 
 

Temperature range

 
 

The operating temperature
A measured relubrication interval can be achieved within given limits. The lubricant should be sufficiently thermally stable at the upper operating temperature and should not be too thick at the lower operating temperature.
of the bearings is limited by:

 
 
  • the dimensional stability of the bearing rings and rolling elements
  • the cage
  • the lubricant
  • the seals.
 
 

 

Possible operating temperatures of double row angular contact ball bearings ➤ Table 1.

 
   
Table 1
Permissible temperature ranges
 

Operating temperature
Double row angular contact ball bearings, open
Double row angular contact ball bearings, sealed
with sheet steel or brass cage
with polyamide cage PA66
imageref_19988082955_All.gif
   
ungreased
–30 °C to +150 °C
–30 °C to +120 °C,
limited by the cage
The part of a rolling bearing which separates, retains and, where necessary, guides the rolling elements
material
–30 °C to +110 °C,
limited by the lubricant
Gaseous, fluid, consistent, plastic or solid material for reduction of friction and wear between two friction elements.
and seal
Elements such as axial face seal, labyrinth seal, rotary shaft seal or gap seal which prevent the ingress of gaseous, liquid and solid materials through the gaps between combined components during movement or whilst stationary
material
series 30, 38, 32..-BD and 33..-BD, D ≦ 90 mm,
–30 °C to +120 °C

 
imageref_18348417035_All.gif   In the event of anticipated temperatures which lie outside the stated values, please contact Schaeffler.  
 

Cages

 

Solid cages made from brass and PA66, as well as sheet steel cages, are used as standard

 

Standard cages and additional cage
The part of a rolling bearing which separates, retains and, where necessary, guides the rolling elements
designs for double row angular contact ball bearings are made from brass, polyamide or steel ➤ Table 2. Other cages are available by agreement. With such cages, however, suitability for high speeds and temperatures as well as the basic load
Load which, for example, is to be supported at a friction point. Also strain from pressure and/or heat.

See Contact surface
ratings may differ from the values for the bearings with standard cages.

 
imageref_18348417035_All.gif   For high continuous temperatures and applications with difficult operating conditions, bearings with brass or sheet steel cages should be used. If there is any uncertainty regarding cage
The part of a rolling bearing which separates, retains and, where necessary, guides the rolling elements
suitability, please consult Schaeffler.
 
 

   
Table 2
Cage, cage
The part of a rolling bearing which separates, retains and, where necessary, guides the rolling elements
suffix, bore code
 

Bearing series
Solid cage
made from polyamide PA66
Solid brass cage
Sheet steel cage
TVH, TVP
M, MA
standard
also available for
standard
also available for
standard
also available for
Bore code
32
- - 19, 21, 22
18, 20
17, 18, 20
-
33
- - 17, 19, 20, 22
18
14 to 16, 18
20
30..-B
up to 08
- - - - -
32..-B
00, 01, 14 to 18, 20
- - - - -
33..-B
01, 12
- - - - -
38..-B
00 to 12, 14, 16, 18, 20
- - - - -
32..-BD
- 02 to 13
- - 02 to 13
-
33..-BD
- 02 to 11, 13, 14, 16
- - 04 to 11, 13, 14
-
33..-DA
05
- 08, 10, 11, 15 to 22
05, 06, 07, 09, 12, 13, 14
06, 07, 09, 12, 13, 14
05

 
 

Internal clearance

 
 

Axial internal clearance – bearings with unsplit inner ring

imageref_17757201419_All.gif   Double row angular contact ball bearings with unsplit inner ring of the basic design have the axial internal clearance CN (group N) in accordance with DIN 628-3:2008 ➤ Table 3.  
imageref_18348417035_All.gif   Bearings can also be supplied with an axial internal clearance which is larger or smaller than CN (C3, C4 or C2). In this case, please contact Schaeffler.  
   
Table 3
Axial internal clearance of double row angular contact ball bearings with unsplit inner ring
 

Nominal
bore diameter
Axial internal clearance
d

mm
C2
(Group 2)
μm
CN
(Group N)
μm
C3
(Group 3)
μm
C4
(Group 4)
μm
over
incl.
min.
max.
min.
max.
min.
max.
min.
max.
- 10
1
11
5
21
12
28
25
45
10
18
1
12
6
23
13
31
27
47
18
24
2
14
7
25
16
34
27
47
24
30
2
15
8
27
18
37
30
50
30
40
2
16
9
29
21
40
33
54
40
50
2
18
11
33
23
44
36
58
50
65
3
22
13
36
26
48
40
63
65
80
3
24
15
40
30
54
46
71
80
100
3
26
18
46
35
63
55
83
100
120
4
30
22
53
42
73
65
96
120
140
4
34
25
59
48
82
74
108

 
 

Axial internal clearance – bearings with split inner ring

Standard corresponds approximately to C3 for unsplit bearings

 

Bearings with a split inner ring are intended for higher axial loads. As a result, they generally also have a tighter fit than unsplit bearings. Their normal internal clearance corresponds approximately to the internal clearance group C3 for unsplit bearings ➤ Table 4.

 
   
Table 4
Axial internal clearance of double row angular contact ball bearings with split inner ring
 

Nominal
bore diameter
Axial internal clearance
d

mm
C2
(Group 2)
μm
CN
(Group N)
μm
C3
(Group 3)
μm
over
incl.
min.
max.
min.
max.
min.
max.
24
30
8
27
16
35
27
46
30
40
9
29
18
38
30
50
40
50
11
33
22
44
36
58
50
65
13
36
25
48
40
63
65
80
15
40
29
54
46
71

 
 

Dimensions, tolerances

 
 

Dimension standards

imageref_17757201419_All.gif   The main dimensions of double row angular contact ball bearings correspond to DIN 628-3:2008. Nominal dimensions of double row angular contact ball bearings ➤ dimension table.  
 

Chamfer dimensions

imageref_17757201419_All.gif   The limiting dimensions for chamfer dimensions correspond to DIN 620‑6:2004. Overview and limiting values   ➤ section. Nominal value of chamfer dimension ➤ dimension table.  
 

Tolerances

imageref_17757201419_All.gif   The tolerances
See
Running accuracy
Dimensional accuracy
for the dimensional and running accuracy
Measured in terms of radial runout and axial runout, due to the dimensional and geometrical tolerances of the bearing in motion, defined according to DIN
of double row angular contact ball bearings correspond to tolerance class Normal in accordance with ISO 492:2014; the dimensional and running tolerances
See
Running accuracy
Dimensional accuracy
of bearings with the suffix BD correspond to the tolerance class 6 in accordance with ISO 492:2014. Tolerance values in accordance with ISO 492 ➤ Table and ➤ Table .
 
 

Suffixes

 
 

For a description of the suffixes used in this chapter ➤ Table 5 and medias interchange http://www.schaeffler.de/std/1D52.

 
   
Table 5
Suffixes and corresponding descriptions
 

Suffix
Description of suffix
B
Modified internal construction,
nominal contact angle α = 25°, without filling slot
Standard
BD
Modified internal construction,
nominal contact angle α = 30°, without filling slot
C2
Axial internal clearance C2 (smaller than normal)
Available
by agreement
C3
Axial internal clearance C3 (larger than normal)
C4
Axial internal clearance C4 (larger than C3)
DA
Inner ring split,
nominal contact angle α = 45°
Standard
M
Solid brass cage, ball-guided
Standard, dependent on bore code
MA
Solid brass cage, guided on outer ring
TVH
Solid cage
The part of a rolling bearing which separates, retains and, where necessary, guides the rolling elements
made from glass fibre reinforced polyamide PA66, ball-guided
2HRS
Contact seal
Elements such as axial face seal, labyrinth seal, rotary shaft seal or gap seal which prevent the ingress of gaseous, liquid and solid materials through the gaps between combined components during movement or whilst stationary
on both sides, axial contact (lip seal)
Standard
2RS
Contact seal
Elements such as axial face seal, labyrinth seal, rotary shaft seal or gap seal which prevent the ingress of gaseous, liquid and solid materials through the gaps between combined components during movement or whilst stationary
on both sides, axial contact (lip seal)
2RSR
Contact seal
Elements such as axial face seal, labyrinth seal, rotary shaft seal or gap seal which prevent the ingress of gaseous, liquid and solid materials through the gaps between combined components during movement or whilst stationary
on both sides, radial contact (lip seal)
2RZ
Non-contact seal
Elements such as axial face seal, labyrinth seal, rotary shaft seal or gap seal which prevent the ingress of gaseous, liquid and solid materials through the gaps between combined components during movement or whilst stationary
on both sides
(rubberised gap seal)
2Z
Non-contact sealing
See Seals
shield on both sides
(sheet metal gap seal)
HRS
Contact seal
Elements such as axial face seal, labyrinth seal, rotary shaft seal or gap seal which prevent the ingress of gaseous, liquid and solid materials through the gaps between combined components during movement or whilst stationary
on one side, axial contact (lip seal)
Special design, available
by agreement
RS
Contact seal
Elements such as axial face seal, labyrinth seal, rotary shaft seal or gap seal which prevent the ingress of gaseous, liquid and solid materials through the gaps between combined components during movement or whilst stationary
on one side, axial contact (lip seal)
RSR
Contact seal
Elements such as axial face seal, labyrinth seal, rotary shaft seal or gap seal which prevent the ingress of gaseous, liquid and solid materials through the gaps between combined components during movement or whilst stationary
on one side, radial contact (lip seal)
RZ
Non-contact seal
Elements such as axial face seal, labyrinth seal, rotary shaft seal or gap seal which prevent the ingress of gaseous, liquid and solid materials through the gaps between combined components during movement or whilst stationary
on one side (rubberised gap seal)
Z
Non-contact sealing
See Seals
shield on one side
(sheet metal gap seal)
XL
X-life bearing, dependent on bore code and
bearing type

 
 

Structure of bearing designation

 

Examples of composition of bearing designation

 

The designation
Identification of a bearing by letters and numbers, indicating, for example, the series, dimensional series or size code, bore diameter, bearing design and information such as Corrotect plating or length of guideways
of bearings follows a set model. Examples ➤ Figure 7 and ➤ Figure 8. The composition of designations is subject to DIN 623-1    ➤ Figure.

 
 

   

Figure 7
Double row angular contact ball bearing of basic design: designation
Identification of a bearing by letters and numbers, indicating, for example, the series, dimensional series or size code, bore diameter, bearing design and information such as Corrotect plating or length of guideways
structure


 

imageref_18345231499_en.gif

 
   

Figure 8
Double row angular contact ball bearing with split inner ring: designation
Identification of a bearing by letters and numbers, indicating, for example, the series, dimensional series or size code, bore diameter, bearing design and information such as Corrotect plating or length of guideways
structure


 

imageref_20050534155_en.gif

 
 

Dimensioning

 
 

Equivalent dynamic bearing load

Valid for α = 25°, 30°, 35°, 45°

 

The calculation of P is dependent on the nominal contact angle α of the bearing, the load
Load which, for example, is to be supported at a friction point. Also strain from pressure and/or heat.

See Contact surface
ratio Fa/Fr and the calculation factors from ➤ Equation 1 to ➤ Equation 8.

 
imageref_17757187211_All.gif   The further fundamental information on the calculation of the equivalent dynamic bearing load
See Equivalent dynamic load
must be observed ➤ section .
 

Equation 1
Equivalent dynamic loadα = 25°
 
imageref_18144062987_All.gif


Equation 2
Equivalent dynamic loadα = 25°
 
imageref_18144077963_All.gif


Equation 3
Equivalent dynamic loadα = 30°
 
imageref_18144080139_All.gif


Equation 4
Equivalent dynamic loadα = 30°
 
imageref_18144082315_All.gif


Equation 5
Equivalent dynamic loadα = 35°
 
imageref_18144084491_All.gif


Equation 6
Equivalent dynamic loadα = 35°
 
imageref_18144150283_All.gif


Equation 7
Equivalent dynamic loadα = 45°
 
imageref_18144152459_All.gif


Equation 8
Equivalent dynamic loadα = 45°
 
imageref_18144167435_All.gif

Legend

 
P
 N
Equivalent dynamic bearing load
Fr
 N
Radial load
Fa
 N
Axial load.
 
 

Equivalent static bearing load

Valid for α = 25°, 30°, 35°, 45°

 

The calculation of the equivalent static bearing load P0 is dependent on the nominal contact angle α and the calculation factors ➤ Equation 9 to ➤ Equation 12.

 
 


Equation 9
Equivalent static loadα = 25°
 
imageref_10903411083_All.gif


Equation 10
Equivalent static loadα = 30°
 
imageref_18144056459_All.gif


Equation 11
Equivalent static loadα = 35°
 
imageref_10903433099_All.gif


Equation 12
Equivalent static loadα = 45°
 
imageref_10903455115_All.gif

Legend

 
P0
 N
Equivalent static bearing load
F0r, F0a
 N
Largest radial or axial load
Force acting in the direction of the shaft.
present (maximum load).
 
 

Static load
Load which, for example, is to be supported at a friction point. Also strain from pressure and/or heat.

See Contact surface
safety factor

S0 = C0/P0

 

In addition to the basic rating life L (L10h), it is also always necessary to check the static load
Load which, for example, is to be supported at a friction point. Also strain from pressure and/or heat.

See Contact surface
safety factor S0
 ➤ Equation 13.

 

Equation 13
Static Load which, for example, is to be supported at a friction point. Also strain from pressure and/or heat.See Contact surface safety factor
 
imageref_27021597814984331_All.gif

Legend

 
S0
Static load
Load which, for example, is to be supported at a friction point. Also strain from pressure and/or heat.

See Contact surface
safety factor
C0
 N
Basic static load
Load which, for example, is to be supported at a friction point. Also strain from pressure and/or heat.

See Contact surface
rating
P0
 N
Equivalent static bearing load.
 
 

Minimum load

 

In order to prevent damage
Loss of essential or required characteristics in equipment, machinery or plant or their component parts.
due to slippage, a minimum radial load
A force which acts at an angle of b = 0°.
of P > C0r/100 is required

 

In order that no slippage occurs between the contact partners, the double row angular contact ball bearings must be constantly subjected to a sufficiently high load. Based on experience, a minimum radial load
A force which acts at an angle of b = 0°.
of the order of P > C0r/100 is thus necessary. In most cases, however, the radial load
A force which acts at an angle of b = 0°.
is already higher than the requisite minimum load
Load which, for example, is to be supported at a friction point. Also strain from pressure and/or heat.

See Contact surface
due to the weight of the supported parts and the external forces.

 
imageref_18348417035_All.gif   If the minimum radial load
A force which acts at an angle of b = 0°.
is lower than indicated above, please consult Schaeffler.
 
 

Design of bearing arrangements

 

Support bearing rings over their entire circumference and width

 

In order to allow full utilisation of the load
Load which, for example, is to be supported at a friction point. Also strain from pressure and/or heat.

See Contact surface
carrying capacity of the bearings and thus also achieve the requisite rating life, the bearing rings must be rigidly and uniformly supported by means of contact surfaces
The effective surface is the surface which separates the object from its surrounding medium.The actual surface is the approximate image from measuring technology of the ideal geometric surface. Note: various measuring processes or measuring conditions (e.g. stylus radius) can give different actual surfaces.The geometric surface is an ideal surface whose nominal form is defined by a drawing or other technical documentation. See DIN 4760 for further details.

See
Surface protection
Surface tension
over their entire circumference and over the entire width of the raceway. Support can be provided by means of a cylindrical seating surface. The seating and contact surfaces
The effective surface is the surface which separates the object from its surrounding medium.The actual surface is the approximate image from measuring technology of the ideal geometric surface. Note: various measuring processes or measuring conditions (e.g. stylus radius) can give different actual surfaces.The geometric surface is an ideal surface whose nominal form is defined by a drawing or other technical documentation. See DIN 4760 for further details.

See
Surface protection
Surface tension
should not be interrupted by grooves, holes or other recesses. The accuracy
Deviation of the actual dimension from the nominal dimension as described by tolerances. For monorail systems, the parallel deviation of the reference surfaces within given tolerances.

See
Running accuracy
Dimensional accuracy
of mating parts must meet specific requirements ➤ Table 6 to ➤ Table 8.

 
 

Radial location of bearings – fit recommendations

For secure radial location, tight fits are necessary

 

In addition to supporting the rings adequately, the bearings must also be securely located in a radial direction, to prevent creep of the bearing rings on the mating parts under load. This is generally achieved by means of tight fits between the bearing rings and the mating parts. If the rings are not secured adequately or correctly, this can cause severe damage
Loss of essential or required characteristics in equipment, machinery or plant or their component parts.
to the bearings and adjacent machine parts. Influencing factors, such as the conditions of rotation, magnitude of the load, internal clearance, temperature conditions, design of the mating parts and the mounting and dismounting options must be taken into consideration in the selection of fits.

 
imageref_17757187211_All.gif   If shock type loads occur, tight fits (transition fit or interference fit) are required to prevent the rings from coming loose at any point. Clearance, transition or interference fits ➤ Table and ➤ Table .  
 

The following information provided in Technical principles must be taken into consideration in the design of bearing arrangements:

 
 
  • conditions of rotation    ➤ link
  • tolerance classes for cylindrical shaft seats (radial bearings) ➤ Table
  • shaft fits    ➤ link
  • tolerance classes for bearing seats in housings (radial bearings) ➤ Table
  • housing fits    ➤ link
 
 

Axial location of bearings – location methods

The bearings must also be securely located in an axial direction

 

As a tight fit alone is not normally sufficient to also locate the bearing rings securely on the shaft and in the housing
See Mounting dimenstions
bore in an axial direction, this must usually be achieved by means of an additional axial location or retention method. The axial location of the bearing rings must be matched to the type of bearing arrangement. Shaft and housing
See Mounting dimenstions
shoulders, housing
See Mounting dimenstions
covers, nuts, spacer rings and retaining rings etc., are fundamentally suitable.

 
 

Dimensional, geometrical and running accuracy
Measured in terms of radial runout and axial runout, due to the dimensional and geometrical tolerances of the bearing in motion, defined according to DIN
of the bearing seats

For bearings with tolerance class Normal, a minimum of IT6 should be provided for the shaft seat and a minimum of IT7 for the housing
See Mounting dimenstions
seat

 

The accuracy
Deviation of the actual dimension from the nominal dimension as described by tolerances. For monorail systems, the parallel deviation of the reference surfaces within given tolerances.

See
Running accuracy
Dimensional accuracy
of the bearing seat on the shaft and in the housing
See Mounting dimenstions
should correspond to the accuracy
Deviation of the actual dimension from the nominal dimension as described by tolerances. For monorail systems, the parallel deviation of the reference surfaces within given tolerances.

See
Running accuracy
Dimensional accuracy
of the bearing used. For double row angular contact ball bearings with the tolerance class Normal, the shaft seat should correspond to a minimum of standard tolerance grade IT6 and the housing
See Mounting dimenstions
seat to a minimum of IT7; with tolerance class 6, the shaft seat should correspond to a minimum of IT5 and the housing
See Mounting dimenstions
seat to a minimum of IT6. Guide values for the geometrical and positional tolerances
See
Running accuracy
Dimensional accuracy
of bearing seating surfaces
The effective surface is the surface which separates the object from its surrounding medium.The actual surface is the approximate image from measuring technology of the ideal geometric surface. Note: various measuring processes or measuring conditions (e.g. stylus radius) can give different actual surfaces.The geometric surface is an ideal surface whose nominal form is defined by a drawing or other technical documentation. See DIN 4760 for further details.

See
Surface protection
Surface tension
➤ Table 6, tolerances t1 to t3 in accordance with   ➤ Figure. Numerical values for IT grades ➤ Table 7.

 
   
Table 6
Guide values for the geometrical and positional tolerances
See
Running accuracy
Dimensional accuracy
of bearing seating surfaces
 

Bearing
tolerance class
Bearing seating surface
Standard tolerance grades to ISO 286-1
(IT grades)
to ISO 492
to DIN 620
Diameter tolerance
Roundness tolerance
Parallelism tolerance
Total axial runout tolerance of abutment shoulder
t1
t2
t3
Normal
PN (P0)
Shaft
IT6 (IT5)
Circumferential load
Load which, for example, is to be supported at a friction point. Also strain from pressure and/or heat.

See Contact surface
IT4/2
Circumferential load
Load which, for example, is to be supported at a friction point. Also strain from pressure and/or heat.

See Contact surface
IT4/2
IT4
Point load
Load which, for example, is to be supported at a friction point. Also strain from pressure and/or heat.

See Contact surface
IT5/2
Point load
Load which, for example, is to be supported at a friction point. Also strain from pressure and/or heat.

See Contact surface
IT5/2
Housing
IT7 (IT6)
Circumferential load
Load which, for example, is to be supported at a friction point. Also strain from pressure and/or heat.

See Contact surface
IT5/2
Circumferential load
Load which, for example, is to be supported at a friction point. Also strain from pressure and/or heat.

See Contact surface
IT5/2
IT5
Point load
Load which, for example, is to be supported at a friction point. Also strain from pressure and/or heat.

See Contact surface
IT6/2
Point load
Load which, for example, is to be supported at a friction point. Also strain from pressure and/or heat.

See Contact surface
IT6/2
6
P6
Shaft
IT5
Circumferential load
IT3/2
Circumferential load
IT3/2
IT3
Point load
IT4/2
Point load
IT4/2
Housing
IT6
Circumferential load
IT4/2
Circumferential load
IT4/2
IT4
Point load
IT5/2
Point load
IT5/2

 
   
Table 7
Numerical values for ISO standard tolerances
See
Running accuracy
Dimensional accuracy
(IT grades) to ISO 286-1:2010
 

IT grade
Nominal dimension in mm
over
3
6
10
18
30
50
80
120
incl.
6
10
18
30
50
80
120
180
Values in μm
IT3
  2,5
2,5
3
4
4
5
6
8
IT4
  4
4
5
6
7
8
10
12
IT5
  5
6
8
9
11
13
15
18
IT6
  8
9
11
13
16
19
22
25
IT7
  12
15
18
21
25
30
35
40

 
 

Roughness of cylindrical bearing seats

Ra must not be too high

 

The roughness
Regular or irregular repeat deviation from an ideal geometric profile.
of the bearing seats must be matched to the tolerance class of the bearings. The mean roughness
Regular or irregular repeat deviation from an ideal geometric profile.
value Ra must not be too high, in order to maintain the interference loss within limits. The shafts must be ground, while the bores must be precision turned. Guide values as a function of the IT grade of bearing seating surfaces
The effective surface is the surface which separates the object from its surrounding medium.The actual surface is the approximate image from measuring technology of the ideal geometric surface. Note: various measuring processes or measuring conditions (e.g. stylus radius) can give different actual surfaces.The geometric surface is an ideal surface whose nominal form is defined by a drawing or other technical documentation. See DIN 4760 for further details.

See
Surface protection
Surface tension
➤ Table 8.

 
   
Table 8
Roughness values for cylindrical bearing seating surfaces
The effective surface is the surface which separates the object from its surrounding medium.The actual surface is the approximate image from measuring technology of the ideal geometric surface. Note: various measuring processes or measuring conditions (e.g. stylus radius) can give different actual surfaces.The geometric surface is an ideal surface whose nominal form is defined by a drawing or other technical documentation. See DIN 4760 for further details.

See
Surface protection
Surface tension
– guide values
 

Nominal diameter
of the bearing seat
d (D)
Recommended mean roughness
Regular or irregular repeat deviation from an ideal geometric profile.
value
for ground bearing seats
Ramax
mm
μm
Diameter tolerance (IT grade)
over
incl.
IT7
IT6
IT5
IT4
- 80
1,6
0,8
0,4
0,2
80
500
1,6
1,6
0,8
0,4

 
 

Mounting dimensions for the contact surfaces
The effective surface is the surface which separates the object from its surrounding medium.The actual surface is the approximate image from measuring technology of the ideal geometric surface. Note: various measuring processes or measuring conditions (e.g. stylus radius) can give different actual surfaces.The geometric surface is an ideal surface whose nominal form is defined by a drawing or other technical documentation. See DIN 4760 for further details.

See
Surface protection
Surface tension
of bearing rings

The contact surfaces
The effective surface is the surface which separates the object from its surrounding medium.The actual surface is the approximate image from measuring technology of the ideal geometric surface. Note: various measuring processes or measuring conditions (e.g. stylus radius) can give different actual surfaces.The geometric surface is an ideal surface whose nominal form is defined by a drawing or other technical documentation. See DIN 4760 for further details.

See
Surface protection
Surface tension
for the rings must be of sufficient height

 

The mounting dimensions
Dimensions such as shaft diameter or hole distances, for example of bearings and guideways, which influence fitting for correct functioning
of the shaft and housing
See Mounting dimenstions
shoulders, and spacer rings etc., must ensure that the contact surfaces
The effective surface is the surface which separates the object from its surrounding medium.The actual surface is the approximate image from measuring technology of the ideal geometric surface. Note: various measuring processes or measuring conditions (e.g. stylus radius) can give different actual surfaces.The geometric surface is an ideal surface whose nominal form is defined by a drawing or other technical documentation. See DIN 4760 for further details.

See
Surface protection
Surface tension
for the bearing rings are of sufficient height. However, they must also reliably prevent rotating parts of the bearing from grazing stationary parts. Proven mounting dimensions
Dimensions such as shaft diameter or hole distances, for example of bearings and guideways, which influence fitting for correct functioning
for the radii and diameters of abutment shoulders ➤ dimension table. These dimensions are limiting dimensions (maximum or minimum dimensions); the actual values should not be higher or lower than specified.

 
 

Mounting and dismounting

 
imageref_17757187211_All.gif   The mounting and dismounting options for angular contact ball bearings, by thermal, hydraulic or mechanical methods, must be taken into consideration in the design of the bearing position.  

Ensure that the bearings are not damaged during mounting

 

In the mounting of non-separable (self-retaining) angular contact ball bearings, the mounting forces must always be applied to the bearing ring with a tight fit.

 
 

Bearings with split inner ring

Simplified mounting of bearings due to split inner ring

 

These angular contact ball bearings are not self-retaining. As a result, the outer ring with the ball and cage
The part of a rolling bearing which separates, retains and, where necessary, guides the rolling elements
assembly can be mounted separately from the two inner ring halves. This gives simplified mounting of the bearings.

 
 

Schaeffler Mounting Handbook

Rolling bearings must be handled with great care

 

Rolling bearings are well-proven precision machine elements for the design of economical and reliable bearing arrangements, which offer high operational security. In order that these products can function correctly and achieve the envisaged operating life
See Life, rating
without detrimental effect, they must be handled with care.

 
imageref_21602891659_en.gif   The Schaeffler Mounting Handbook MH 1 gives comprehensive infor­mation about the correct storage, mounting, dismounting and mainten­ance of rotary rolling bearings http://www.schaeffler.de/std/1D53. It also provides information which should be observed by the designer, in relation to the mounting, dismounting and maintenance
Inspection, maintenance and repair of equipment and machines.
of bearings, in the original design of the bearing position. This book is available from Schaeffler on request.
 
 

Legal notice regarding data freshness

 

The further development of products may also result in technical changes to catalogue products

 

Of central interest to Schaeffler is the further development and opti­misation of its products and the satisfaction of its customers. In order that you, as the customer, can keep yourself optimally informed about the progress that is being made here and with regard to the current technical status of the products, we publish any product changes which differ from the printed version in our electronic product catalogue.

 
imageref_18350433803_All.gif   We therefore reserve the right to make changes to the data and illus­trations in this catalogue. This catalogue reflects the status at the time of printing. More recent publications released by us (as printed or digital media) will automatically precede this catalogue if they involve the same subject. Therefore, please always use our electronic product catalogue to check whether more up-to-date information or modification notices exist for your desired product.  
 

Further information

 

In addition to the data in this chapter, the following chapters in Technical principles must also be observed in the design of bearing arrangements:

 
   
   
  
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