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Design of bearing arrangements

Arrangement of bearings

Support of a shaft normally requires two bearings

The guidance and support of a rotating machine part generally requires at least two bearings arranged at a certain distance from each other (exceptions: four point contact, crossed roller and slewing bearings). Depending on the application, a decision is made between a locating/non-locating bearing arrangement, an adjusted bearing arrangement and a floating bearing arrangement.

Locating/non-locating bearing arrangement

The non-locating bearing compensates for differences in distance

On a shaft supported by two radial bearings, the distances between the bearing seats on the shaft and in the housing frequently do not coincide as a result of manufacturing tolerances. The distances may also change as a result of temperature increases during operation. These differences in distance are compensated in the non-locating bearing. Examples of locating/non-locating bearing arrangements ➤ Figure.

Non-locating bearings

Suitable non-locating bearings

Ideal non-locating bearings are cylindrical roller bearings with cage of series N and NU or needle roller bearings. In these bearings, the roller and cage assembly can be displaced on the raceway of the bearing ring without ribs. All other bearing types, for example deep groove ball bearings and spherical roller bearings, can only act as non-locating bearings if one bearing ring has a fit that allows displacement. The bearing ring subjected to point load therefore has a loose fit; this is normally the outer ring.

Locating bearings

The locating bearing guides the shaft in an axial direction and supports external axial forces. In order to prevent axial bracing, shafts with more than two bearings have only one locating bearing. The type of bearing selected as a locating bearing depends on the magnitude of the axial forces and the accuracy with which the shafts must be axially guided.

Suitable locating bearings

A double row angular contact ball bearing, for example, will give closer axial guidance than a deep groove ball bearing or a spherical roller bearing. A pair of symmetrically arranged angular contact ball bearings or tapered roller bearings used as locating bearings will also provide extremely close axial guidance.

There are particular advantages in using angular contact ball bearings of the universal design. The bearings can be fitted in pairs in any O or X arrangement without shims. Angular contact ball bearings of the universal design are matched so that, in an X or O arrangement, they have a low axial internal clearance (design UA), zero clearance (UO) or slight preload (UL).

In gearboxes, a four point contact bearing is sometimes fitted directly adjacent to a cylindrical roller bearing to give a locating bearing arrangement. The four point contact bearing, without radial support of the outer ring, can only support axial forces. The radial force is supported by the cylindrical roller bearing.

If a lower axial force is present, a cylindrical roller bearing with cage of series NUP can also be used as a locating bearing.

No adjustment or setting work with matched pairs of tapered roller bearings

Fitting is also made easier when using matched pairs of tapered roller bearings as locating bearings (313..-N11CA). They are matched with appropriate axial internal clearance so that no adjustment or setting work is required.

Locating/non-locating bearing arrangements


= non-locating bearing


Locating bearing: deep groove ball bearing
Non-locating bearing: deep groove ball bearing


Locating bearing: spherical roller bearing
Non-locating bearing: spherical roller bearing


Locating bearing: deep groove ball bearing
Non-locating bearing: cylindrical roller bearing NU


Locating bearing: spherical roller bearing
Non-locating bearing: toroidal roller bearing


Locating bearing: double row angular contact ball bearing
Locating bearing: cylindrical roller bearing NU


Locating bearing: four point contact bearing and cylindrical roller bearing NU (outer ring of four point contact bearing not radially retained)
Non-locating bearing: cylindrical roller bearing NU


Locating bearing: tapered roller bearing
Non-locating bearing: cylindrical roller bearing NU


Locating bearing: cylindrical roller bearing NUP
Non-locating bearing: cylindrical roller bearing NU

Adjusted bearing arrangement

The “adjustment” process

An adjusted bearing arrangement is generally constructed from two angular contact bearings (angular contact ball bearings, tapered roller bearings) in a mirror image arrangement ➤ Figure and ➤ Figure. The inner and outer rings of the bearings are displaced relative to each other until the required clearance or the required preload is achieved. This process is known as “adjustment”.

Angular contact bearings and deep groove ball bearings suitable for adjusted bearing arrangements

Angular contact bearings support radial and axial forces

Angular contact bearings support forces comprising a radial and an axial component. These are thus a combination of a radial and an axial bearing. Depending on the size of the nominal contact angle α, angular contact bearings are classified as radial or axial bearings.

Deep groove ball bearings are also suitable

Deep groove ball bearings can also be used for an adjusted bearing arrangement; these are then angular contact ball bearings with a small nominal contact angle.

Due to the possibility of regulating the clearance, adjusted bearing arrangements are particularly suitable if close guidance is necessary.

O or X arrangement

Two arrangements

In an adjusted bearing arrangement, an O or X arrangement of the bearings is essentially possible.

The contact cone apexes point outwards or inwards

In the O arrangement, the cones and their apexes formed by the contact lines (the contact cone apexes S) point outwards, in the X arrangement, the cones point inwards ➤ Figure.

In angular contact ball bearings and tapered roller bearings, the contact lines of the rolling element forces coincide at the contact cone apexes S ➤ Figure and ➤ Figure. In adjusted bearing arrangements, the bearing spacing is therefore defined as the spacing of the contact cone apexes.

The support spacing is larger in an O arrangement

The resulting support spacing H is larger in an O arrangement than in an X arrangement. An O arrangement should be used in preference if the component with small bearing spacing must be guided with the smallest possible tilting clearance or tilting forces must be supported.

Adjusted bearing arrangement with angular contact ball bearings

S = contact cone apex

H = support spacing


O arrangement


X arrangement

Influence of thermal expansion in O and X arrangements

When deciding between an O and X arrangement, attention must also be paid to the temperature conditions and thermal expansions. This is based on the position of the roller cone apexes R. The roller cone apex R represents the intersection point of the extended, inclined outer ring raceway with the bearing axis ➤ Figure.

X arrangement

If the shaft is warmer than the housing (TW > TG ), the shaft expands more than the housing in an axial and radial direction. As a result, the clearance set in an X arrangement decreases in every case (assuming the following precondition: shaft and housing of same material).

Adjusted bearing arrangement with tapered roller bearings

X arrangement

R = roller cone apex

S = contact cone apex


Temperature behaviour and thermal expansion in an O arrangement

The behaviour is different in an O arrangement. A distinction must be drawn between three cases here:

  • If the roller cone apexes R coincide at a point, the axial and radial thermal expansion cancel each other out and the clearance set is maintained ➤ Figure
  • If the roller cones overlap with a small bearing spacing, the radial expansion has a stronger effect than the axial expansion on the bearing clearance ➤ Figure: the axial clearance is reduced. This must be taken into consideration in the adjustment of bearings
  • In the third case, the roller cones do not overlap with a large bearing spacing ➤ Figure. The radial expansion then has a weaker effect than the axial expansion on the bearing clearance: the axial clearance is increased

Adjusted bearings in an O arrangement, the roller cone apexes coincide

R = roller cone apex

S = contact cone apex

Adjusted bearings in an O arrangement, the roller cone apexes overlap

R = roller cone apex

S = contact cone apex

Adjusted bearings in an O arrangement, the roller cone apexes do not overlap

R = roller cone apex

S = contact cone apex

Sliding seat in the bearing ring to be adjusted

Sliding seat only permissible on the bearing ring with point load

Whether the inner ring or outer ring is adjusted depends on the degree of accessibility of the adjustment elements, such as nuts and covers. Since the bearing ring to be adjusted must be easily displaced, attention must also be paid in these considerations to the fits of the bearing rings.

A sliding seat should fundamentally only be permitted on the ring that is subject to point load.

Elastic adjustment

Preloading using springs

Adjusted bearing arrangements can also be achieved by preloading using springs ➤ Figure. This elastic adjustment method compensates for thermal expansion. It can also be used where bearing arrangements are at risk of vibration while stationary.

Bearing arrangement adjusted by means of spring washer


Deep groove ball bearing


Spring washer (spring preload)


Cover

Floating bearing arrangement

Difference from the adjusted bearing arrangement: this does not give close axial guidance

The floating bearing arrangement is essentially similar in its arrangement to the adjusted bearing arrangement. While freedom from clearance or even preload is desirable when warm from operation in the latter case, floating bearing arrangements always have an axial clearance s of several tenths of a millimetre depending on the bearing size ➤ Figure. The value s is defined as a function of the required guidance accuracy such that the bearings are not axially stressed even under unfavourable thermal conditions.

Suitable bearing types

A floating bearing arrangement is suitable for bearings that must not be adjusted

For a floating bearing arrangement, almost all bearing types can be considered that must not be adjusted; examples ➤ Figure. Floating arrangements are thus possible with, for example, deep groove ball bearings, self-aligning ball bearings and spherical roller bearings; one ring of each of the two bearings (usually the outer ring) then has a sliding seat. In the floating bearing arrangement with cylindrical roller bearings NJ, length compensation is possible within the bearing.

Tapered roller bearings and angular contact ball bearings are not suitable for a floating bearing arrangement, since these bearings must be adjusted in order to run correctly.

Floating bearing arrangements

s = axial displacement distance (axial clearance)


Deep groove ball bearing


Spherical roller bearing


Cylindrical roller bearing NJ

Radial location of bearings

Location of the bearing rings in a radial and tangential direction by fit, in an axial direction by form fit

Rolling bearings must be located on the shaft and in the housing in a radial, axial and tangential direction in accordance with their function. In a radial and tangential direction, this occurs by means of a tight fit. However, this is only possible under certain conditions in an axial direction, therefore rolling bearings are generally axially located by means of form fit.

Criteria for selection of fits

Points to be observed in the selection of fits

The following must be taken into consideration in determining the fit:

  • The rolling bearing rings must be well supported over their entire circumference in order to allow full utilisation of the load carrying capacity of the bearing
  • The rings must not creep on their mating parts, otherwise the seating surfaces will be damaged
  • The non-locating bearing must compensate changes in the length of the shaft and housing and one ring must therefore be axially adjustable
  • Mounting and dismounting of the bearings should be possible without a large amount of work

Interference fits

Interference fits lead to expansion of the inner ring raceway and contraction of the outer ring raceway. The resulting stresses occurring in the rings and the reduction in the radial internal clearance must be taken into consideration in the selection of the fit; see ➤ link and ➤ link.

Tight fit necessary

Good support of the bearing rings on their circumference requires rigid seating. The requirement that rings must not creep on their mating parts also requires firm seating. If non-separable bearings must be mounted and dismounted, a tight fit can only be achieved for one bearing ring. In the case of cylindrical roller bearings N, NU and needle roller bearings, both rings can have tight fits, since the length compensation takes place within the bearing and since the rings can be mounted separately. With tight fits and a temperature differential between the inner and outer ring, the radial internal clearance of the bearing is reduced. This must be taken into consideration when selecting the radial internal clearance.

Materials other than cast iron or steel

If materials other than cast iron or steel are used for the adjacent construction, the modulus of elasticity and the differing coefficients of thermal expansion of the materials must also be be taken into consideration to achieve rigid seating. For aluminium housings, thin-walled housings and hollow shafts, a closer fit should be selected if necessary in order to achieve the same force locking as with cast iron, steel or solid shafts.

Higher loads

Higher loads, especially shocks, require a fit with larger interference and narrower geometrical tolerances.

Bearing seat for axial bearings

Axial bearings, which support axial loads only, must not be guided radially (with the exception of axial cylindrical roller bearings which have a degree of freedom in the radial direction due to flat raceways). In the case of groove-shaped raceways this is not present and must be achieved by a loose seat for the stationary washer. A rigid seat is normally selected for the rotating washer.

Where axial bearings also support radial forces, such as in axial spherical roller bearings, fits should be selected in the same way as for radial bearings.

Contact surfaces of the mating parts

The contact surfaces of the mating parts must be perpendicular to the axis of rotation (total axial runout tolerance to IT5 or better), in order to ensure uniform load distribution over all the rolling elements.

Conditions of rotation

Point or circumferential load

The conditions of rotation indicate the motion of one bearing ring with respect to the load direction and are expressed as either circumferential load or point load ➤ Table.

For point load, a loose fit is also possible

If the bearing ring is stationary relative to the load direction (point load on the ring), no forces occur that could cause creep of the ring. A tight fit would be desirable here in order to give better support, but a loose fit is also possible since there is no risk that the ring will undergo creep. There is essentially a risk, however, that fretting corrosion will occur.

For circumferential load, a firm bearing seat is necessary

A bearing ring that rotates relative to the load direction (circumferential load on the ring) will roll on its seat if a loose fit is present and will thus creep in a circumferential direction. If shock type load is present, the ring will slip. In both cases, there is a risk that the seats of the ring and mating part will be damaged by fretting corrosion and wear.

The possible creep or slippage of a bearing ring can only be effectively prevented by a firm bearing seat.

Differentiation between point load and circumferential load

Condition of rotation

Example

Schematic

Load case

Fit

Rotating inner ring, stationary outer ring

Shaft with weight load

Circumferential load
on inner ring and point load on outer ring

Inner ring:
tight fit necessary

Outer ring:
loose fit permissible

Constant load direction

Shaft with weight load

Stationary inner ring, rotating outer ring

Hub bearing arrangement with significant imbalance

Circumferential load
on inner ring and point load on outer ring

Inner ring:
tight fit necessary

Outer ring:
loose fit permissible

Load direction rotates with outer ring

Hub bearing arrangement with significant imbalance

Stationary inner ring, rotating outer ring

Passenger car front wheel track roller (hub bearing arrangement)

Point load on inner ring and circumferential load
on outer ring

Inner ring:
loose fit permissible

Outer ring:
tight fit necessary

Constant load direction

Passenger car front wheel track roller (hub bearing arrangement)

Rotating inner ring, stationary outer ring

Centrifuge, vibrating screen

Point load on inner ring and circumferential load
on outer ring

Inner ring:
loose fit permissible

Outer ring:
tight fit necessary

Load direction rotates with inner ring

Centrifuge, vibrating screen

Recommended fits

Shaft and housing tolerances

ISO tolerance classes

The tolerances are defined in the form of ISO tolerance classes to ISO 286‑1 and ISO 286-2. The designation of the tolerance classes, e. g. “E8”, comprises one or two upper case letters for housings or lower case letters for shafts (= fundamental deviation identifier, which defines the tolerance position relative to the zero line, e. g. “E”) and the grade number of the standard tolerance grade (this defines the tolerance quality, e. g. “8”). A schematic illustration of the most common rolling bearing fits is shown in ➤ Figure.

Shaft and housing fits for rolling bearings

D = nominal bearing outside diameter

d = nominal bearing bore diameter

tΔDmp = deviation of mean bearing outside diameter (in accordance with ISO 492)

tΔdmp = deviation of mean bearing bore diameter (in accordance with ISO 492)


Zero line


Housing


Shaft


Clearance fit


Transition fit


Interference fit


Recommendations for shaft and housing tolerances

The tables ➤ Table to ➤ Table contain recommendations for the selection of shaft and housing tolerances that are valid for normal mounting and operating conditions. Deviations are possible if particular requirements apply, for example in relation to running accuracy, smooth running or operating temperature. Increased running accuracies thus require closer tolerances such as standard tolerance grade 5 instead of 6. If the inner ring is warmer than the shaft during operation, the seating may loosen to an impermissible extent. A tighter fit must then be selected, for example m6 instead of k6.

Objective: the best overall solution

In some applications, the question of fits can only be resolved by a compromise. The individual requirements must be weighed against each other and those selected that give the best overall solution.

Tolerance classes for cylindrical shaft seats (radial bearings)

Condition
of rotation1)

Bearing type

Shaft diameter

Displacement facility

Load

Tolerance class2)
of shaft

mm

over

incl.

Point load on inner ring

Ball bearings, roller bearings

All sizes

Inner ring easily displaced

g6 (g5)

Ball bearings, roller bearings All sizes

Inner ring not easily displaced, angular contact ball bearings and tapered roller bearings with adjusted inner ring

h6 (j6)

Needle
roller bearings

All sizes

Non-locating bearing

h6 (g6)3)

Circumfer­ential load on inner ring
or indeter­minate load direction
Ball bearings

50

Normal loads4)

j6 (j5)

50

100

Low loads5)

j6 (j5)

50 100

Normal and high loads6)

k6 (k5)

100

200

Low loads4)

k6 (m6)

100 200

Normal and high loads7)

m6 (m5)

200

Low loads

m6 (m5)

200

Normal and high loads

n6 (n5)

Roller bearings

60

Low loads

j6 (j5)

60 Normal and high loads k6 (k5)
60 200 Low loads k6 (k5)
60 200 Normal loads m6 (m5)
60 200 High loads n6 (n5)
200 500 Normal loads m6 (n6)
200 500 High loads, shocks p6
500 Normal loads n6 (p6)
500 High loads p6
Needle roller bearings

50

Low loads

k6

50 Normal and high loads m6
50 120 Low loads m6
50 120 Normal and high loads n6

120

250

Low loads

n6

120 250

Normal and high loads

p6

250

400

Low loads

p6

250 400

Normal and high loads

r6

400

500

Low loads

r6

400 500

Normal and high loads

s6

500 Low loads r6
500 Normal and high loads s6
  1. Condition of rotation ➤ Table.
  2. The envelope requirement Ⓔ ➤ Figure applies.
  3. For easy fitting.
  4. C0/P > 10.
  5. C0/P > 12.
  6. C0/P < 12.
  7. C0/P < 10.

Tolerance classes for cylindrical shaft seats (axial bearings)

Load

Bearing type

Shaft diameter

Operating conditions

Tolerance class1)
of shaft

mm

over

incl.

Axial load

Axial deep groove ball bearings

All sizes

j6

Axial deep groove ball bearings, double direction

All sizes

k6

Axial cylindrical roller bearings with shaft locating washer

All sizes

h8

Axial cylindrical roller and cage assemblies

All sizes

h8
Combined load

Axial spherical roller bearings

All sizes

Point load on shaft locating washer

j6
Axial spherical roller bearings

200

Circumferential load on shaft locating washer

j6 (k6)

Axial spherical roller bearings

200

Circumferential load on shaft locating washer

k6 (m6)

  1. The envelope requirement Ⓔ ➤ Figure applies.

Tolerance classes for bearing seats in housings (radial bearings)

Condition
of rotation1)

Displacement facility

Load

Operating conditions

Tolerance class2)
of bore

Point load on outer ring

Outer ring easily displaced, housing unsplit

The tolerance grade
is determined by
the running accuracy required

H7 (H6)3)

Outer ring easily displaced, housing split

The tolerance grade
is determined by
the running accuracy required

H8 (H7)

Outer ring not easily displaced, housing unsplit

High running accuracy required

H6 (J6)

Outer ring not easily displaced, angular contact ball bearings and tapered roller bearings with adjusted outer ring, housing split

Normal running accuracy

H7 (J7)

Outer ring easily displaced

Heat input via shaft

G74)
Circumfer­ential load on outer ring or indeter­minate load direction

Low loads, outer ring cannot be displaced

High requirements
for running accuracy:
K6, M6, N6 and P6

K7 (K6)

Normal loads, shocks, outer ring cannot be displaced

High requirements
for running accuracy:
K6, M6, N6 and P6

M7 (M6)

High loads, shocks (C0/P < 6), outer ring cannot be displaced

High requirements
for running accuracy:
K6, M6, N6 and P6

N7 (N6)

High loads, severe shocks, thin‑walled housing, outer ring cannot be displaced

High requirements
for running accuracy:
K6, M6, N6 and P6

P7 (P6)

  1. Condition of rotation ➤ Table.
  2. The envelope requirement Ⓔ ➤ Figure applies.
  3. G7 for housings made from flake graphite cast iron, with bearing outside diameter D > 250 mm and temperature differential between outer ring and housing > 10 K.
  4. F7 for housings made from flake graphite cast iron, with bearing outside diameter D > 250 mm and temperature differential between outer ring and housing > 10 K.

Tolerance classes for bearing seats in housings (axial bearings)

Load

Bearing type

Operating conditions

Tolerance class1)
of bore

Axial load

Axial deep groove ball bearings

Normal running accuracy

E8

Axial deep groove ball bearings

High running accuracy

H6

Axial cylindrical roller bearings with housing locating washer

H9

Axial cylindrical roller and cage assemblies

H10

Axial spherical roller bearings

Normal loads

E8

Axial spherical roller bearings

High loads

G7

Combined loads, point load
on housing locating washer

Axial spherical roller bearings

H7
Combined loads, circumferential load
on housing locating washer

Axial spherical roller bearings

K7
  1. The envelope requirement Ⓔ ➤ Figure applies.

Tables of fits

Clearance, transition and interference fits for shafts and housing bores

Machining tolerances for shafts and housing bores are shown in ➤ Figure, ➤ Table and ➤ Table. The values are valid for solid steel shafts and flake graphite cast iron housings. In the table header, below the nominal diameters, are the normal tolerances for the bore or outside diameter of radial bearings (excluding tapered roller bearings). Below these are the deviations for the most important tolerance classes for mounting of rolling bearings.

Example for shaft fit, tolerance class j5

For the shaft ⌀ 40 j5 Ⓔ, ➤ Table gives an example of how to read the numerical values.

Example for housing fit, tolerance class K6

For the housing bore ⌀ 100 K6 Ⓔ, ➤ Table gives an example explaining the group of numbers.

Shaft fits

Nominal shaft diameter in mm

over

incl.

3

6

 6

10

10

18

 18

 30

 30

 50

 50

 65

over

incl.

 65

 80

 80

100

100

120

120

140

140

160

over

incl.

160

180

180

200

200

220

220

250

250

280

over

incl.

280

315

315

355

355

400

400

450

450

500

over

incl.

500

560

560

630

630

710

710

800

800

900

over

incl.

Deviations of bearing bore diameter in μm (tolerance class Normal)

tΔdmp

 0

–8

 0

–8

 0

–8

  0

–10

  0

–12

  0

–15

tΔdmp

  0

–15

  0

–20

  0

–20

  0

–25

  0

–25

tΔdmp

  0

–25

  0

–30

  0

–30

  0

–30

  0

–35

tΔdmp

  0

–35

  0

–40

  0

–40

  0

–45

  0

–45

tΔdmp

  0

–50

  0

–50

  0

–75

  0

–75

   0

–100

tΔdmp

Shaft deviation, fit interference or fit clearance in μm

f6

–10

–18

2

7

18

–13

–22

5

11

22

–16

–27

8

15

27

–20

–33

10

17

33

–25

–41

13

22

41

–30

–49

15

26

49

f6

–30

–49

15

26

49

–36

–58

16

30

58

–36

–58

16

30

58

–43

–68

18

34

68

–43

–68

18

34

68

f6

–43

–68

18

34

68

–50

–79

20

40

79

–50

–79

20

40

79

–50

–79

20

40

79

–56

–88

21

44

88

f6

–56

–88

21

44

88

–62

–98

22

47

98

–62

–98

22

47

98

–68

–108

23

51

108

–68

–108

23

51

108

f6

–76

–120

26

58

120

–76

–120

26

58

120

–80

–130

5

47

130

–80

–130

5

47

130

–86

–146

14

39

146

f6

g5

–4

–9

4

0

9

–5

–11

3

2

11

–6

–14

2

3

14

–7

–16

3

3

16

–9

–20

3

5

20

–10

–23

5

4

23

g5

–10

–23

5

4

23

–12

–27

8

4

27

–12

–27

8

4

27

–14

–32

11

3

32

–14

–32

11

3

32

g5

–14

–32

11

3

32

–15

–35

15

2

35

–15

–35

15

2

35

–15

–35

15

2

35

–17

–40

18

1

40

g5

–17

–40

18

1

40

–18

–43

22

0

43

–18

–43

22

0

43

–20

–47

25

1

47

–20

–47

25

1

47

g5

g5

g6

–4

–12

4

1

12

–5

–14

3

3

14

–6

–17

2

4

17

–7

–20

3

5

20

–9

–25

3

6

25

–10

–29

5

6

29

g6

–10

–29

5

6

29

–12

–34

8

6

34

–12

–34

8

6

34

–14

–39

11

6

39

–14

–39

11

6

39

g6

–14

–39

11

6

39

–15

–44

15

5

44

–15

–44

15

5

44

–15

–44

15

5

44

–17

–49

18

4

49

g6

–17

–49

18

4

49

–18

–54

22

3

54

–18

–54

22

3

54

–20

–60

25

3

60

–20

–60

25

3

60

g6

–22

–66

28

4

66

–22

–66

28

4

66

–24

–74

51

9

74

–24

–74

51

9

74

–26

–82

74

24

82

g6

h5

0

–5

8

4

5

0

–6

8

3

6

0

–8

8

3

8

0

–9

10

4

9

0

–11

12

4

11

0

–13

15

6

13

h5

0

–13

15

6

13

0

–15

20

8

15

0

–15

20

8

15

0

–18

25

11

18

0

–18

25

11

18

h5

0

–18

25

11

18

0

–20

30

13

20

0

–20

30

13

20

0

–20

30

13

20

0

–23

35

16

23

h5

0

–23

35

16

23

0

–25

40

18

25

0

–25

40

18

25

0

–27

45

21

27

0

–27

45

21

27

h5

0

–32

50

23

32

0

–32

50

23

32

0

–36

75

38

36

0

–36

75

38

36

0

–40

100

53

40

h5

h6

0

–8

8

3

8

0

–9

8

2

9

0

–11

8

2

11

0

–13

10

2

13

0

–16

12

3

16

0

–19

15

4

19

h6

0

–19

15

4

19

0

–22

20

6

22

0

–22

20

6

22

0

–25

25

8

25

0

–25

25

8

25

h6

0

–25

25

8

25

0

–29

30

10

29

0

–29

30

10

29

0

–29

30

10

29

0

–32

35

13

32

h6

0

–32

35

13

32

0

–36

40

15

36

0

–36

40

15

36

0

–40

45

17

40

0

–40

45

17

40

h6

0

–44

50

18

44

0

–44

50

18

44

0

–50

75

33

50

0

–50

75

33

50

0

–56

100

48

56

h6

Nominal shaft diameter in mm

over

incl.

3

6

 6

10

10

18

 18

 30

 30

 50

 50

 65

over

incl.

 65

 80

 80

100

100

120

120

140

140

160

over

incl.

160

180

180

200

200

220

220

250

250

280

over

incl.

280

315

315

355

355

400

400

450

450

500

over

incl.

500

560

560

630

630

710

710

800

800

900

over

incl.

Deviations of bearing bore diameter in μm (tolerance class Normal)

tΔdmp

 0

–8

 0

–8

 0

–8

  0

–10

  0

–12

  0

–15

tΔdmp

  0

–15

  0

–20

  0

–20

  0

–25

  0

–25

tΔdmp

  0

–25

  0

–30

  0

–30

  0

–30

  0

–35

tΔdmp

  0

–35

  0

–40

  0

–40

  0

–45

  0

–45

tΔdmp

  0

–50

  0

–50

  0

–75

  0

–75

   0

–100

tΔdmp

Shaft deviation, fit interference or fit clearance in μm

j5

+3

–2

11

7

2

+4

–2

12

7

2

+5

–3

13

8

3

+5

–4

15

9

4

+6

–5

18

10

5

+6

–7

21

12

7

j5

+6

–7

21

12

7

+6

–9

26

14

9

+6

–9

26

14

9

+7

–11

32

18

11

+7

–11

32

18

11

j5

+7

–11

32

18

11

+7

–13

37

20

13

+7

–13

37

20

13

+7

–13

37

20

13

+7

–16

42

23

16

j5

+7

–16

42

23

16

+7

–18

47

25

18

+7

–18

47

25

18

+7

–20

52

28

20

+7

–20

52

28

20

j5

j5

j6

+6

–2

14

8

2

+7

–2

15

9

2

+8

–3

16

10

3

+9

–4

19

11

4

+11

–5

23

14

5

+12

–7

27

16

7

j6

+12

–7

27

16

7

+13

–9

33

19

9

+13

–9

33

19

9

+14

–11

39

22

11

+14

–11

39

22

11

j6

+14

–11

39

22

11

+16

–13

46

26

13

+16

–13

46

26

13

+16

–13

46

26

13

+16

–16

51

29

16

j6

+16

–16

51

29

16

+18

–18

58

33

18

+18

–18

58

33

18

+20

–20

65

37

20

+20

–20

65

37

20

j6

j6

js5

+2,5

–2,5

11

6

3

+3

–3

11

6

3

+4

–4

12

6

4

+4,5

–4,5

15

9

5

+5,5

–5,5

18

10

6

+6,5

–6,5

22

13

7

js5

+6,5

–6,5

22

13

7

+7,5

–7,5

28

16

8

+7,5

–7,5

28

16

8

+9

–9

34

20

9

+9

–9

34

20

9

js5

+9

–9

34

20

9

+10

–10

40

23

10

+10

–10

40

23

10

+10

–10

40

23

10

+11,5

–11,5

47

27

12

js5

+11,5

–11,5

47

27

12

+12,5

–12,5

53

32

13

+12,5

–12,5

53

32

13

+13,5

–13,5

59

35

14

+13,5

–13,5

59

35

14

js5

+16

–16

65

38

16

+16

–16

65

38

16

+18

–18

91

55

18

+18

–18

91

55

18

+20

–20

118

72

20

js5

js6

+4

–4

12

7

4

+4,5

–4,5

13

7

5

+5,5

–5,5

14

8

6

+6,5

–6,5

17

9

7

+8

–8

20

11

8

+9,5

–9,5

25

13

10

js6

+9,5

–9,5

25

13

10

+11

–11

31

17

11

+11

–11

31

17

11

+12,5

–12,5

38

21

13

+12,5

–12,5

38

21

13

js6

+12,5

–12,5

38

21

13

+14,5

–14,5

45

25

15

+14,5

–14,5

45

25

15

+14,5

–14,5

45

25

15

+16

–16

51

29

16

js6

+16

–16

51

29

16

+18

–18

58

33

18

+18

–18

58

33

18

+20

–20

65

37

20

+20

–20

65

37

20

js6

+22

–22

72

40

22

+22

–22

72

40

22

+25

–25

100

58

25

+25

–25

100

58

25

+28

–28

128

76

28

js6

k5

+6

+1

14

9

1

+7

+1

15

10

1

+9

+1

17

12

1

+11

+2

21

15

2

+13

+2

25

17

2

+15

+2

30

21

2

k5

+15

+2

30

21

2

+18

+3

38

26

3

+18

+3

38

26

3

+21

+3

46

32

3

+21

+3

46

32

3

k5

+21

+3

46

32

3

+24

+4

54

37

4

+24

+4

54

37

4

+24

+4

54

37

4

+27

+4

62

43

4

k5

+27

+4

62

43

4

+29

+4

69

47

4

+29

+4

69

47

4

+32

+5

77

53

5

+32

+5

77

53

5

k5

k5

k6

+9

+1

17

11

1

+10

+1

18

12

1

+12

+1

20

14

1

+15

+2

25

17

2

+18

+2

30

21

2

+21

+2

36

25

2

k6

+21

+2

36

25

2

+25

+3

45

31

3

+25

+3

45

31

3

+28

+3

53

36

3

+28

+3

53

36

3

k6

+28

+3

53

36

3

+33

+4

63

43

4

+33

+4

63

43

4

+33

+4

63

43

4

+36

+4

71

49

4

k6

+36

+4

71

49

4

+40

+4

80

55

4

+40

+4

80

55

4

+45

+5

90

62

5

+45

+5

90

62

5

k6

+44

0

94

62

0

+44

0

94

62

0

+50

0

125

83

0

+50

0

125

83

0

+56

0

156

104

0

k6

Nominal shaft diameter in mm

over

incl.

3

6

 6

10

10

18

 18

 30

 30

 50

 50

 65

over

incl.

 65

 80

 80

100

100

120

120

140

140

160

over

incl.

160

180

180

200

200

220

220

250

250

280

over

incl.

280

315

315

355

355

400

400

450

450

500

over

incl.

500

560

560

630

630

710

710

800

800

900

over

incl.

Deviations of bearing bore diameter in μm (tolerance class Normal)

tΔdmp

 0

–8

 0

–8

 0

–8

  0

–10

  0

–12

  0

–15

tΔdmp

  0

–15

  0

–20

  0

–20

  0

–25

  0

–25

tΔdmp

  0

–25

  0

–30

  0

–30

  0

–30

  0

–35

tΔdmp

  0

–35

  0

–40

  0

–40

  0

–45

  0

–45

tΔdmp

  0

–50

  0

–50

  0

–75

  0

–75

   0

–100

tΔdmp

Shaft deviation, fit interference or fit clearance in μm

m5

+9

+4

17

13

4

+12

+6

20

15

6

+15

+7

23

18

7

+17

+8

27

21

8

+20

+9

32

24

9

+24

+11

39

30

11

m5

+24

+11

39

30

11

+28

+13

48

36

13

+28

+13

48

36

13

+33

+15

58

44

15

+33

+15

58

44

15

m5

+33

+15

58

44

15

+37

+17

67

50

17

+37

+17

67

50

17

+37

+17

67

50

17

+43

+20

78

59

20

m5

+43

+20

78

59

20

+46

+21

86

64

21

+46

+21

86

64

21

+50

+23

95

71

23

+50

+23

95

71

23

m5

m5

m6

+12

+4

20

15

4

+15

+6

23

17

6

+18

+7

26

20

7

+21

+8

31

23

8

+25

+9

37

27

9

+30

+11

45

34

11

m6

+30

+11

45

34

11

+35

+13

55

42

13

+35

+13

55

42

13

+40

+15

65

48

15

+40

+15

65

48

15

m6

+40

+15

65

48

15

+46

+17

76

56

17

+46

+17

76

56

17

+46

+17

76

56

17

+52

+20

87

65

20

m6

+52

+20

87

65

20

+57

+21

97

72

21

+57

+21

97

72

21

+63

+23

108

80

23

+63

+23

108

80

23

m6

+70

+26

120

88

26

+70

+26

120

88

26

+80

+30

155

113

30

+80

+30

155

113

30

+90

+34

190

138

34

m6

n5

+13

+8

21

17

8

+16

+10

24

19

10

+20

+12

28

23

12

+24

+15

34

28

15

+28

+17

40

32

17

+33

+20

48

39

20

n5

+33

+20

48

39

20

+38

+23

58

46

23

+38

+23

58

46

23

+45

+27

70

56

27

+45

+27

70

56

27

n5

+45

+27

70

56

27

+51

+31

81

64

31

+51

+31

81

64

31

+51

+31

81

64

31

+57

+34

92

73

34

n5

+57

+34

92

73

34

+62

+37

102

80

37

+62

+37

102

80

37

+67

+40

112

88

40

+67

+40

112

88

40

n5

n5

n6

+16

+8

24

19

8

+19

+10

27

21

10

+23

+12

31

25

12

+28

+15

38

30

15

+33

+17

45

36

17

+39

+20

54

43

20

n6

+39

+20

54

43

20

+45

+23

65

51

23

+45

+23

65

51

23

+52

+27

77

60

27

+52

+27

77

60

27

n6

+52

+27

77

60

27

+60

+31

90

70

31

+60

+31

90

70

31

+60

+31

90

70

31

+66

+34

101

79

34

n6

+66

+34

101

79

34

+73

+37

113

88

37

+73

+37

113

88

37

+80

+40

125

97

40

+80

+40

125

97

40

n6

+88

+44

138

106

44

+88

+44

138

106

44

+100

+50

175

133

50

+100

+50

175

133

50

+112

+56

212

160

56

n6

p6

+20

+12

28

23

12

+24

+15

32

26

15

+29

+18

37

31

18

+35

+22

45

37

22

+42

+26

54

45

26

+51

+32

66

55

32

p6

+51

+32

66

55

32

+59

+37

79

65

37

+59

+37

79

65

37

+68

+43

93

76

43

+68

+43

93

76

43

p6

+68

+43

93

76

43

+79

+50

109

89

50

+79

+50

109

89

50

+79

+50

109

89

50

+88

+56

123

101

56

p6

+88

+56

123

101

56

+98

+62

138

113

62

+98

+62

138

113

62

+108

+68

153

125

68

+108

+68

153

125

68

p6

+122

+78

172

140

78

+122

+78

172

140

78

+138

+88

213

171

88

+138

+88

213

171

88

+156

+100

256

204

100

p6

Nominal shaft diameter in mm

over

incl.

3

6

 6

10

10

18

 18

 30

 30

 50

 50

 65

over

incl.

 65

 80

 80

100

100

120

120

140

140

160

over

incl.

160

180

180

200

200

220

220

250

250

280

over

incl.

280

315

315

355

355

400

400

450

450

500

over

incl.

500

560

560

630

630

710

710

800

800

900

over

incl.

Deviations of bearing bore diameter in μm (tolerance class Normal)

tΔdmp

 0

–8

 0

–8

 0

–8

  0

–10

  0

–12

  0

–15

tΔdmp

  0

–15

  0

–20

  0

–20

  0

–25

  0

–25

tΔdmp

  0

–25

  0

–30

  0

–30

  0

–30

  0

–35

tΔdmp

  0

–35

  0

–40

  0

–40

  0

–45

  0

–45

tΔdmp

  0

–50

  0

–50

  0

–75

  0

–75

   0

–100

tΔdmp

Shaft deviation, fit interference or fit clearance in μm

p7

+24

+12

32

25

12

+30

+15

38

30

15

+36

+18

44

35

18

+43

+22

53

43

22

+51

+26

63

51

26

+62

+32

77

62

32

p7

+62

+32

77

62

32

+72

+37

92

73

37

+72

+37

92

73

37

+83

+43

108

87

43

+83

+43

108

87

43

p7

+83

+43

108

87

43

+96

+50

126

101

50

+96

+50

126

101

50

+96

+50

126

101

50

+108

+56

143

114

56

p7

+108

+56

143

114

56

+119

+62

159

127

62

+119

+62

159

127

62

+131

+68

176

139

68

+131

+68

176

139

68

p7

+148

+78

198

158

78

+148

+78

198

158

78

+168

+88

243

199

88

+168

+88

243

199

88

+190

+100

290

227

100

p7

r6

+23

+15

31

25

15

+28

+19

36

30

19

+34

+23

42

35

23

+41

+28

51

44

28

+50

+34

62

53

34

+60

+41

75

64

41

r6

+62

+43

77

66

43

+73

+51

93

79

51

+76

+54

96

82

54

+88

+63

113

97

63

+90

+65

115

99

65

r6

+93

+68

118

102

68

+106

+77

136

116

77

+109

+80

139

119

80

+113

+84

143

123

84

+126

+94

161

138

94

r6

+130

+98

165

142

98

+144

+108

184

159

108

+150

+114

190

165

114

+166

+126

211

183

126

+172

+132

217

189

132

r6

+194

+150

244

212

150

+199

+155

249

217

155

+225

+175

300

258

175

+235

+185

310

268

185

+266

+210

366

314

210

r6

r7

+27

+15

35

28

15

+34

+19

42

34

19

+41

+23

49

40

23

+49

+28

59

49

28

+59

+34

71

59

34

+71

+41

86

71

41

r7

+73

+43

88

73

43

+86

+51

106

87

51

+89

+54

109

90

54

+103

+63

128

107

63

+105

+65

130

109

65

r7

+108

+68

133

112

68

+123

+77

153

128

77

+126

+80

156

131

80

+130

+84

160

135

84

+146

+94

181

152

94

r7

+150

+98

185

156

98

+165

+108

205

173

108

+171

+114

211

179

114

+189

+126

234

198

126

+195

+132

240

204

132

r7

+220

+150

270

230

150

+225

+155

275

235

155

+255

+175

330

278

175

+265

+185

340

288

185

+300

+210

400

337

210

r7

s6

+27

+19

35

30

19

+32

+23

40

34

23

+39

+28

47

41

28

+48

+35

58

50

35

+59

+43

71

62

43

+72

+53

87

76

53

s6

+78

+59

93

82

59

+93

+71

113

99

71

+101

+79

121

107

79

+117

+92

142

125

92

+125

+100

150

133

100

s6

+133

+108

158

141

108

+151

+122

181

161

122

+159

+130

189

169

130

+169

+140

199

179

140

+190

+158

225

203

158

s6

+202

+170

237

215

170

+226

+190

266

241

190

+244

+208

284

259

208

+272

+232

317

289

232

+292

+252

337

309

252

s6

+324

+280

374

343

280

+354

+310

404

373

310

+390

+340

465

423

340

+430

+380

505

463

380

+486

+430

586

534

430

s6

Example

Example:
shaft ⌀ 40 j5 Ⓔ

Maximum material value

+6

18
10

Interference or fit clearance if the maximum material values are combined. Probable interference or fit clearance

Minimum material value

–5

 5

Interference or fit clearance if the minimum material values are combined

Values in bold type in the group of three indicate fit interference, values in normal type indicate fit clearance.

Housing fits

Nominal housing bore diameter in mm

Nominal housing bore diameter in mm

over

incl.

 6

10

10

18

18

30

    30

    50

    50

    80

 80

120

120

150

150

180

over

incl.

180

250

250

315

315

400

400

500

500

630

630

800

  800

1 000

1 000

1 250

Deviations of bearing outside diameter in μm (tolerance class Normal)

Deviations of bearing outside diameter in μm (tolerance class Normal)

tΔDmp

 0

–8

 0

–8

 0

–9

  0

–11

  0

–13

  0

–15

  0

–18

  0

–25

tΔDmp

  0

–30

  0

–35

  0

–40

  0

–45

  0

–50

  0

–75

   0

–100

   0

–125

Housing deviation, fit interference or fit clearance in μm

Housing deviation, fit interference or fit clearance in μm

E8

+47

+25

25

35

55

+59

+32

32

44

67

+73

+40

40

54

82

+89

+50

50

67

100

+106

+60

60

79

119

+126

+72

72

85

141

+148

+85

85

112

166

+148

+85

85

114

173

E8

+172

+100

100

134

202

+191

+110

110

149

226

+214

+125

125

168

254

+232

+135

135

182

277

+255

+145

145

199

305

+285

+160

160

227

360

+310

+170

170

250

410

+360

+195

195

292

485

F7

+28

+13

13

21

36

+34

+16

16

25

42

+41

+20

20

30

50

+50

+25

25

37

61

+60

+30

30

44

73

+71

+36

36

53

86

+83

+43

43

62

101

+83

+43

43

64

108

F7

+96

+50

50

75

126

+108

+56

56

85

143

+119

+62

62

94

159

+131

+68

68

104

176

+146

+76

76

116

196

+160

+80

80

132

235

+176

+86

86

149

276

+203

+98

98

175

328

G6

+14

+5

5

11

22

+17

+6

6

12

25

+20

+7

7

14

29

+25

+9

9

18

36

+29

+10

10

21

42

+34

+12

12

24

49

+39

+14

14

28

57

+39

+14

14

31

64

G6

+44

+15

15

35

74

+49

+17

17

39

84

+54

+18

18

43

94

+60

+20

20

48

105

+66

+22

22

54

116

+74

+24

24

66

149

+82

+26

26

78

182

+94

+28

28

93

219

G7

+20

+5

5

13

28

+24

+6

6

15

32

+28

+7

7

17

37

+34

+9

9

21

45

+40

+10

10

24

53

+47

+12

12

29

62

+54

+14

14

33

72

+54

+14

14

36

79

G7

+61

+15

15

40

91

+69

+17

17

46

104

+75

+18

18

50

115

+83

+20

20

56

128

+92

+22

22

62

142

+104

+24

24

76

179

+116

+26

26

89

216

+133

+28

28

105

258

H6

+9

0

0

6

17

+11

0

0

6

19

+13

0

0

7

22

+16

0

0

9

27

+19

0

0

11

32

+22

0

0

12

37

+25

0

0

14

43

+25

0

0

17

50

H6

+29

0

0

20

59

+32

0

0

22

67

+36

0

0

25

76

+40

0

0

28

85

+44

0

0

32

94

+50

0

0

42

125

+56

0

0

52

156

+66

0

0

64

191

Nominal housing bore diameter in mm

over

incl.

 6

10

10

18

18

30

    30

    50

    50

    80

 80

120

120

150

150

180

over

incl.

180

250

250

315

315

400

400

500

500

630

630

800

  800

1 000

1 000

1 250

Deviations of bearing outside diameter in μm (tolerance class Normal)

tΔDmp

 0

–8

 0

–8

 0

–9

  0

–11

  0

–13

  0

–15

  0

–18

  0

–25

tΔDmp

  0

–30

  0

–35

  0

–40

  0

–45

  0

–50

  0

–75

   0

–100

   0

–125

Housing deviation, fit interference or fit clearance in μm

H7

+15

0

0

8

23

+18

0

0

9

26

+21

0

0

10

30

+25

0

0

12

36

+30

0

0

14

43

+35

0

0

17

50

+40

0

0

19

58

+40

0

0

22

65

H7

+46

0

0

25

76

+52

0

0

29

87

+57

0

0

32

97

+63

0

0

36

108

+70

0

0

40

120

+80

0

0

52

155

+90

0

0

63

190

+105

0

0

77

230

H8

+22

0

0

10

30

+27

0

0

12

35

+33

0

0

14

42

+39

0

0

17

50

+46

0

0

20

59

+54

0

0

23

69

+63

0

0

27

81

+63

0

0

29

88

H8

+72

0

0

34

102

+81

0

0

39

116

+89

0

0

43

129

+97

0

0

47

142

+110

0

0

54

160

+125

0

0

67

200

+140

0

0

80

240

+165

0

0

97

290

J6

+5

–4

4

2

13

+6

–5

5

1

14

+8

–5

5

2

17

+10

–6

6

3

21

+13

–6

6

5

26

+16

–6

6

6

31

+18

–7

7

7

36

+18

–7

7

10

43

J6

+22

–7

7

13

52

+25

–7

7

15

60

+29

–7

7

18

69

+33

–7

7

21

78

J7

+8

–7

7

1

16

+10

–8

8

1

18

+12

–9

9

1

21

+14

–11

11

1

25

+18

–12

12

2

31

+22

–13

13

4

37

+26

–14

14

5

44

+26

–14

14

8

51

J7

+30

–16

16

9

60

+36

–16

16

13

71

+39

–18

18

14

79

+43

–20

20

16

88

JS6

+4,5

–4,5

4,5

2

12,5

+5,5

–5,5

5,5

1

13,5

+6,5

–6,5

6,5

0

15,5

+8

–8

8

1

19

+9,5

–9,5

9,5

0

22,5

+11

–11

11

1

26

+12,5

–12,5

12,5

1

30,5

+12,5

–12,5

12,5

3

37,5

JS6

+14,5

–14,5

14,5

5

44,5

+16

–16

16

7

51

+18

–18

18

6

58

+20

–20

20

8

65

+22

–22

22

10

72

+25

–25

25

17

100

+28

–28

28

24

128

+33

–33

33

31

158

Nominal housing bore diameter in mm

over

incl.

 6

10

10

18

18

30

    30

    50

    50

    80

 80

120

120

150

150

180

over

incl.

180

250

250

315

315

400

400

500

500

630

630

800

  800

1 000

1 000

1 250

Deviations of bearing outside diameter in μm (tolerance class Normal)

tΔDmp

 0

–8

 0

–8

 0

–9

  0

–11

  0

–13

  0

–15

  0

–18

  0

–25

tΔDmp

  0

–30

  0

–35

  0

–40

  0

–45

  0

–50

  0

–75

   0

–100

   0

–125

Housing deviation, fit interference or fit clearance in μm

JS7

+7,5

–7,5

7,5

1

15,5

+9

–9

9

0

17

+10,5

–10,5

10,5

1

19,5

+12,5

–12,5

12,5

1

23,5

+15

–15

15

1

28

+17,5

–17,5

17,5

1

32,5

+20

–20

20

1

38

+20

–20

20

1

45

JS7

+23

–23

23

2

53

+26

–26

26

3

61

+28,5

–28,5

28,5

3

68,5

+31,5

–31,5

31,5

4

76,5

+35

–35

35

5

85

+40

–40

40

12

115

+45

–45

45

18

145

+52,5

–52,5

52

24

177

K6

+2

–7

7

1

10

+2

–9

9

3

10

+2

–11

11

4

11

+3

–13

13

4

14

+4

–15

15

4

17

+4

–18

18

6

19

+4

–21

21

7

22

+4

–21

21

4

29

K6

+5

–24

24

4

35

+5

–27

27

5

40

+7

–29

29

4

47

+8

–32

32

4

53

0

–44

44

12

50

0

–50

50

8

75

0

–56

56

4

100

0

–66

66

2

125

K7

+5

–10

10

2

13

+6

–12

12

3

14

+6

–15

15

5

15

+7

–18

18

6

18

+9

–21

21

7

22

+10

–25

25

8

25

+12

–28

28

9

30

+12

–28

28

6

37

K7

+13

–33

33

8

43

+16

–36

36

7

51

+17

–40

40

8

57

+18

–45

45

9

63

0

–70

70

30

50

0

–80

80

28

75

0

–90

90

27

100

0

–105

105

28

125

M6

–3

–12

12

6

5

–4

–15

15

9

4

–4

–17

17

10

5

–4

–20

20

11

7

–5

–24

24

13

8

–6

–28

28

16

9

–8

–33

33

19

10

–8

–33

33

16

17

M6

–8

–37

37

17

22

–9

–41

41

19

26

–10

–46

46

21

30

–10

–50

50

22

35

–26

–70

70

38

24

–30

–80

80

38

45

–34

–90

90

38

66

–40

–106

106

45

85

M7

0

–15

15

7

8

0

–18

18

9

8

0

–21

21

11

9

0

–25

25

13

11

0

–30

30

16

13

0

–35

35

18

15

0

–40

40

21

18

0

–40

40

18

25

M7

0

–46

46

21

30

0

–52

52

23

35

0

–57

57

25

40

0

–63

63

27

45

–26

–96

96

56

24

–30

–110

110

58

45

–34

–124

124

61

66

–40

–145

145

68

85

Nominal housing bore diameter in mm

over

incl.

 6

10

10

18

18

30

    30

    50

    50

    80

 80

120

120

150

150

180

over

incl.

180

250

250

315

315

400

400

500

500

630

630

800

  800

1 000

1 000

1 250

Deviations of bearing outside diameter in μm (tolerance class Normal)

tΔDmp

 0

–8

 0

–8

 0

–9

  0

–11

  0

–13

  0

–15

  0

–18

  0

–25

tΔDmp

  0

–30

  0

–35

  0

–40

  0

–45

  0

–50

  0

–75

   0

–100

   0

–125

Housing deviation, fit interference or fit clearance in μm

N6

–7

–16

16

10

1

–9

–20

20

14

1

–11

–24

24

17

2

–12

–28

28

19

1

–14

–33

33

22

1

–16

–38

38

26

1

–20

–45

45

31

2

–20

–45

45

28

5

N6

–22

–51

51

31

8

–25

–57

57

35

10

–26

–62

62

37

14

–27

–67

67

39

18

–44

–88

88

56

6

–50

–100

100

58

25

–56

–112

112

60

44

–66

–132

132

67

59

N7

–4

–19

19

11

4

–5

–23

23

14

3

–7

–28

28

18

2

–8

–33

33

21

3

–9

–39

39

25

4

–10

–45

45

28

5

–12

–52

52

33

3

–12

–52

52

30

13

N7

–14

–60

60

35

16

–14

–66

66

37

21

–16

–73

73

41

24

–17

–80

80

44

28

–44

–114

114

74

6

–50

–130

130

78

25

–56

–146

146

83

44

–66

–171

171

94

59

P6

–12

–21

21

15

4

–15

–26

26

20

7

–18

–31

31

24

9

–21

–37

37

28

10

–26

–45

45

34

13

–30

–52

52

40

15

–36

–61

61

47

18

–36

–61

61

44

11

P6

–41

–70

70

50

11

–47

–79

79

57

12

–51

–87

87

62

11

–55

–95

95

67

10

–78

–122

122

90

28

–88

–138

138

96

13

–100

–156

156

104

0

–120

–186

186

121

5

P7

–9

–24

24

16

1

–11

–29

29

20

3

–14

–35

35

25

5

–17

–42

42

30

6

–21

–51

51

37

8

–24

–59

59

42

9

–28

–68

68

49

10

–28

–68

68

46

3

P7

–33

–79

79

54

3

–36

–88

88

59

1

–41

–98

98

66

1

–45

–108

108

72

0

–78

–148

148

108

28

–88

–168

168

126

13

–100

–190

190

127

0

–120

–225

225

148

5

Example

Housing ⌀ 100 K6 Ⓔ

Minimum material value

 +4

18
 6

Interference or fit clearance if the maximum material values are combined. Probable interference or fit clearance

Maximum material value

–18

19

Interference or fit clearance if the minimum material values are combined

Values in bold type in the group of three indicate fit interference, values in normal type indicate fit clearance.

Shaft tolerances for adapter sleeves and withdrawal sleeves are shown in ➤ Table.

Shaft tolerances for adapter sleeves and withdrawal sleeves

Nominal
shaft diameter

Shaft tolerance

h7/

h8/

h9/

mm

μm

μm

μm

over

incl.

3

6

0

–12

2,5

0

–18

2,5

0

–30

4

6

10

0

–15

3

0

–22

3

0

–36

4,5

10

18

0

–18

4

0

–27

4

0

–43

5,5

18

30

0

–21

4,5

0

–33

4,5

0

–52

6,5

30

50

0

–25

5,5

0

–39

5,5

0

–62

8

50

65

0

–30

6,5

0

–46

6,5

0

–74

9,5

65

80

0

–30

6,5

0

–46

6,5

0

–74

9,5

80

100

0

–35

7,5

0

–54

7,5

0

–87

11

100

120

0

–35

7,5

0

–54

7,5

0

–87

11

120

140

0

–40

9

0

–63

9

0

–100

12,5

140

160

0

–40

9

0

–63

9

0

–100

12,5

160

180

0

–40

9

0

–63

9

0

–100

12,5

180

200

0

–46

10

0

–72

10

0

–115

14,5

200

220

0

–46

10

0

–72

10

0

–115

14,5

220

250

0

–46

10

0

–72

10

0

–115

14,5

250

280

0

–52

11,5

0

–81

11,5

0

–130

16

280

315

0

–52

11,5

0

–81

11,5

0

–130

16

315

355

0

–57

12,5

0

–89

12,5

0

–140

18

355

400

0

–57

12,5

0

–89

12,5

0

–140

18

400

450

0

–63

13,5

0

–97

13,5

0

–155

20

450

500

0

–63

13,5

0

–97

13,5

0

–155

20

500

560

0

–70

16

0

–110

16

0

–175

22

560

630

0

–70

16

0

–110

16

0

–175

22

630

710

0

–80

18

0

–125

18

0

–200

25

710

800

0

–80

18

0

–125

18

0

–200

25

800

900

0

–90

20

0

–140

20

0

–230

28

The numbers printed in italics give guide values for the cylindricity tolerance t1 (DIN EN ISO 1101) ➤ Figure.

Enveloping circle

For bearings without an inner ring, the enveloping circle Fw ➤ Figure is used. This is the inner inscribed circle of the rolling elements in clearance-free contact with the outer raceway. The enveloping circle for unfitted machined needle roller bearings is in the tolerance class F6 and for drawn cup needle roller bearings in the tolerance class F8. Deviations for F6 and F8 ➤ Table.

Enveloping circle

Fw = enveloping circle diameter


Rolling element


Outer raceway

Deviations for the enveloping circle diameter

Enveloping
circle diameter Fw

Tolerance class F6

Tolerance class F8

mm

Tolerance for enveloping circle diameter Fw

Tolerance for enveloping circle diameter Fw

Upper deviation

Lower deviation

Upper deviation

Lower deviation

over

incl.

μm

μm

μm

μm

3

6

+18

+10

+28

+10

6

10

+22

+13

+35

+13

10

18

+27

+16

+43

+16

18

30

+33

+20

+53

+20

30

50

+41

+25

+64

+25

50

80

+49

+30

+76

+30

80

120

+58

+36

+90

+36

120

180

+68

+43

+106

+43

180

250

+79

+50

+122

+50

250

315

+88

+56

+137

+56

315

400

+98

+62

+151

+62

400

500

+108

+68

+165

+68

Dimensional, geometrical and running accuracy of mating parts

In order to achieve the required fit, the bearing seats and fit surfaces of the shaft and housing bore must conform to certain tolerances ➤ Figure and ➤ Table.

Guide values for the geometrical and positional tolerances of bearing seating surfaces

t1 = roundness tolerance

t2 = parallelism tolerance

t3 = total axial runout tolerance of abutment shoulders

t4 = coaxiality tolerance

Accuracy of bearing seating surfaces

ISO fundamental tolerances

The degree of accuracy for the bearing seat tolerances on the shaft and in the housing, as well as the ISO fundamental tolerances, are shown in ➤ Table (DIN ISO 286-1:2010).

Second bearing seat

The positional tolerances t4 for a second bearing seat on the shaft (d2) or in the housing (D2) are dependent on the types of bearings used and the operating conditions.

Housings

In split housings, the joints must be free from burrs. The accuracy of the bearing seats is determined as a function of the accuracy of the bearing selected.

Guide values for the geometrical and positional tolerances of bearing seating surfaces

Bearing
tolerance class

Bearing seating surface

Fundamental tolerance grades1)

to ISO 492

to DIN 620

Diameter tolerance

Roundness tolerance

Parallelism tolerance

Total
axial runout tolerance
of abutment shoulder

t1

t2

t3

Normal

6X

PN (P0)

P6X

Shaft

IT6 (IT5)

Circumfer­ential load

IT4/2

Circumfer­ential load

IT4/2

IT4
Shaft IT6 (IT5)

Point load

IT5/2

Point load

IT5/2

IT4

Housing

IT7 (IT6)

Circumfer­ential load

IT5/2

Circumfer­ential load

IT5/2

IT5
Housing IT7 (IT6)

Point load

IT6/2

Point load

IT6/2

IT5

6

P6

Shaft

IT5

Circumfer­ential load

IT3/2

Circumfer­ential load

IT3/2

IT3
Shaft IT5

Point load

IT4/2

Point load

IT4/2

IT3

Housing

IT6

Circumfer­ential load

IT4/2

Circumfer­ential load

IT4/2

IT4
Housing IT6

Point load

IT5/2

Point load

IT5/2

IT4

5

P5

Shaft

IT5

Circumfer­ential load

IT2/2

Circumfer­ential load

IT2/2

IT2
Shaft IT5

Point load

IT3/2

Point load

IT3/2

IT2

Housing

IT6

Circumfer­ential load

IT3/2

Circumfer­ential load

IT3/2

IT3
Housing IT6

Point load

IT4/2

Point load

IT4/2

IT3

4

P4

P4S2)

SP2)

Shaft

IT4

Circumfer­ential load

IT1/2

Circumfer­ential load

IT1/2

IT1
Shaft IT4

Point load

IT2/2

Point load

IT2/2

IT1

Housing

IT5

Circumfer­ential load

IT2/2

Circumfer­ential load

IT2/2

IT2
Housing IT5

Point load

IT3/2

Point load

IT3/2

IT2

UP2)

Shaft

IT3

Circumfer­ential load

IT0/2

Circumfer­ential load

IT0/2

IT0
Shaft IT3

Point load

IT1/2

Point load

IT1/2

IT0

Housing

IT4

Circumfer­ential load

IT1/2

Circumfer­ential load

IT1/2

IT1
Housing IT4

Point load

IT2/2

Point load

IT2/2

IT1
  1. ISO fundamental tolerances (IT grades) in accordance with DIN ISO 286. Values for IT grades ➤ Table.
  2. Not included in DIN 620.

Roughness of bearing seats

Ra must not be too high

The roughness of the bearing seats must be matched to the tolerance class of the bearings. The mean roughness value Ra must not be too high, in order to maintain the interference loss within limits. Shafts must be ground, while bores must be precision turned. For further information on this subject ➤ Table and product chapter.

Roughness values for cylindrical bearing seating surfaces – guide values

Nominal diameter
of bearing seat

d (D)

Recommended mean roughness 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

500

1  250

3,21)

1,6

1,6

0,8

  1. For the mounting of bearings using the hydraulic method, a value Ra = 1,6 μm must not be exceeded

Numerical values for IT grades

➤ Table shows numerical values for the ISO fundamental tolerances (IT grades) in accordance with DIN ISO 286-1:2010.

IT grades and values

IT grade

Nominal dimension in mm

over

  –

3

6

10

18

30

50

80

incl.

3

6

10

18

30

50

80

120

Values in μm

IT01

0,3

0,4

0,4

0,5

0,6

0,6

0,8

1

IT0

0,5

0,6

0,6

0,8

1

1

1,2

1,5

IT1

0,8

1

1

1,2

1,5

1,5

2

2,5

IT2

1,2

1,5

1,5

2

2,5

2,5

3

4

IT3

2

2,5

2,5

3

4

4

5

6

IT4

3

4

4

5

6

7

8

10

IT5

4

5

6

8

9

11

13

15

IT6

6

8

9

11

13

16

19

22

IT7

10

12

15

18

21

25

30

35

IT8

14

18

22

27

33

39

46

54

IT9

25

30

36

43

52

62

74

87

IT10

40

48

58

70

84

100

120

140

IT11

60

75

90

110

130

160

190

220

IT12

100

120

150

180

210

250

300

350

continued ▼

IT grades and values

IT grade

Nominal dimension in mm

over

120

180

250

315

400

500

630

   800

incl.

180

250

315

400

500

630

800

1  000

Values in μm

IT01

1,2

2

2,5

3

4

IT0

2

3

4

5

6

IT1

3,5

4,5

6

7

8

9

10

11

IT2

5

7

8

9

10

11

13

15

IT3

8

10

12

13

15

16

18

21

IT4

12

14

16

18

20

22

25

28

IT5

18

20

23

25

27

32

36

40

IT6

25

29

32

36

40

44

50

56

IT7

40

46

52

57

63

70

80

90

IT8

63

72

81

89

97

110

125

140

IT9

100

115

130

140

155

175

200

230

IT10

160

185

210

230

250

280

320

360

IT11

250

290

320

360

400

440

500

560

IT12

400

460

520

570

630

700

800

900

continued ▲

Seats for adapter sleeves and withdrawal sleeves

Seat diameter tolerances for adapter sleeves and withdrawal sleeves

Adapter and withdrawal sleeves are used if increased requirements are not made on the running accuracy of the bearing. For the seats, diameter tolerances corresponding to the IT grades 7 to 9 are possible, while the geometrical deviation can be 50% of this value.

Tapered bearing seats for radial bearings

Geometrical and positional tolerances of the shaft

Guide values for the machining of tapered bearing seats on shafts are shown in ➤ Figure, ➤ Table.

This information does not apply to super precision cylindrical roller bearings in machine tools (spindle bearing arrangement). For information on this subject, see the catalogue Super precision bearings SP 1.

Taper gauges

Schaeffler taper gauges can be used to check for adherence to the recommended tolerances.

Guide values for the geometrical and positional tolerances of tapered bearing seats

B = bearing width

SL = L · taper ratio (1:12, 1:30)

tΔSL′ = taper angle tolerance

t1 = roundness tolerance
➤ Table

t6 = perpendicularity tolerance = 2/3 · t2;
values for t2
➤ Table

z = recommended mean roughness
➤ Table


The tolerances for taper angle tΔSL relative to the bearing width B can be found in the table ➤ Table.

Taper angle tolerance of tapered bearing seats, relative to bearing width

Bearing width B

mm
Taper angle tolerance
tΔSL
from to
Deviations
over incl. upper
μm
lower
μm
uper
μm
lower
μm
16 25 +8 0 +12,5 0
25 40 +10 0 +16 0
40 63 +12,5 0 +20 0
63 100 +16 0 +25 0
100 160 +20 0 +32 0
160 250 +25 0 +40 0
250 400 +32 0 +50 0
400 630 +40 0 +63 0


Determine tΔSL by means of interpolation

For bearing widths with nominal dimensions between the values listed in the table, the taper angle tolerance tΔSL should be determined by means of interpolation of the upper deviations ➤ Equation.

Interpolation of the taper angle tolerance

For a taper of length L, the taper angle tolerance tΔSL′ of the entire taper applies ➤ Equation.

Taper angle tolerance of the entire taper

Example of tolerance calculation

Given:

  • bearing width B = 90 mm
  • taper ratio 1:12
  • taper length L = 100 mm

The tolerance tΔSL′/2 is thus 0 to +12 μm.

In order to calculate the taper slope SL (nominal dimension), the taper length L is multiplied by the taper ratio (1:12) ➤ Equation.

Taper slope

The nominal dimension for SL/2 is thus 4,166 mm; SL/2 = 4,166 +0,012/0.

The data can then be entered in the drawing as follows ➤ Figure.

Example of drawing entry for dimensional tolerances

Checking of a shaft

Measured values:

  • d1′ = 120 mm
  • d2′ = 128,345 mm

The taper slope is calculated from the measured values using ➤ Equation.

Taper slope


The value for SL/2 is thus within tolerance.

Axial location of bearings

Securing the bearing rings against axial creep by means of form fit

In order to prevent the bearing rings co-rotating, they are radially fixed by means of a tight fit. At the same time, the rings must be axially located in both directions so that they cannot undergo lateral creep. Axial creep cannot be prevented solely by a tight fit, especially not if a radial bearing must support large axial forces. For axial location, the bearing rings must therefore be connected by form fit to the shaft or the housing.

Examples

Solutions proven in practice for individual bearing arrangements (locating bearing arrangement, non-locating bearing arrangement, adjusted/ floating bearing arrangement) and the axial location of bearing rings in certain bearing types are described below. Specific features of the individual bearing types are covered in the product chapters.

Guidelines for axial location of bearing rings

Locating bearing arrangement

Locating bearings can support axial forces in both directions

Locating bearings must in general also support axial forces. For the axial location of bearing rings, form fit elements such as shoulders, snap rings, covers, caps, nuts etc. have proved effective.

➤ Figure shows bearing types that can be used as locating bearings and can support axial forces in both directions. The arrows in ➤ Figure to ➤ Figure indicate what task the axial location methods perform in the various types of mounting and types of bearing, such as axial location on both sides of the outer and inner ring of the deep groove ball bearing.

In locating bearing arrangements, both bearing rings must always be abutted on both sides. The fasteners must be matched to the magnitude of the axial forces present.

Axial location of bearing rings in locating bearings


= the means of location must support significant axial forces


Cylindrical roller bearing NUP


Deep groove ball bearing


Spherical roller bearing


Angular contact ball bearing pair


Double direction axial deep groove ball bearing


Cylindrical roller bearing, deep groove ball bearing

The cylindrical roller bearing NUP and deep groove ball bearing support alternating axial forces. Both rings must therefore be axially located on both sides.

Spherical roller bearing

The spherical roller bearing must, as a locating bearing, support axial forces from alternating directions. In this example, the inner ring is located by means of a withdrawal sleeve.

Angular contact ball bearings

The pair of angular contact ball bearings forms a locating bearing in which the two single row bearings are adjusted against each other in mounting. For location on the shaft, readjustable fasteners, such as nuts, are suitable.

Double direction axial deep groove ball bearing

The double direction axial deep groove ball bearing should be seen as a closed bearing group. The shaft locating washer is axially located on both sides, while the housing locating washers are each located on one side. In order that the ball and cage assemblies are guided correctly in the raceway grooves, the bearing is mounted clearance-free by adjustment of the housing locating washers.

Non-locating bearing arrangement

The means of axial location only needs to prevent lateral creep of the bearing rings

Non-locating bearings must only support slight axial forces. The axial location method only needs to prevent lateral creep of the rings. The simplest way of achieving this is by a tight fit. In the case of non-separable bearings, the rotating bearing ring has a tight fit. The other ring is axially retained by the rolling elements. ➤ Figure shows rolling bearings that can be used as non-locating bearings.

Axial location of bearing rings in non-locating bearings


= the means of location must prevent axial creep of the ring


= the means of location must support significant axial forces


Cylindrical roller bearing NU


Deep groove ball bearing


Spherical roller bearing


Barrel roller bearing


Two single row angular contact ball bearings, adjusted in a pair


Cylindrical roller bearing NU

The cylindrical roller bearing NU is designed such that the inner ring can be displaced relative to the roller and cage assembly. For this reason, both bearing rings must also be secured against axial creep on both sides.

Deep groove ball bearing

In the deep groove ball bearing, only the inner ring is located, while the outer ring is axially retained by the rolling elements.

Spherical roller bearing, barrel roller bearing, angular contact ball bearings

In the spherical roller bearing and barrel roller bearing, as well as in the angular contact ball bearing pair, the outer ring is guided axially by the rolling elements. The inner ring of the barrel roller bearing is located on the shaft with or without an adapter sleeve. Location by means of an adapter sleeve secures the bearing against lateral creep.

Adjusted single row angular contact ball bearings

In the adjusted pair of single row angular contact ball bearings, the inner rings are clamped against each other so that they are not forced apart by the axial component of the radial force.

Adjusted or floating bearing arrangement

The bearings can support axial loads in one direction only

Bearings mounted in an adjusted and floating arrangement can support axial load in one direction only; this also applies to single direction axial bearings. The axial forces are supported by shaft or housing shoulders, snap rings, covers etc.

Angular contact ball bearing, cylindrical roller bearing

The angular contact ball bearing in ➤ Figure supports axial forces in one direction only. The bearing rings therefore only require abutment on one side each in accordance with the force pattern. The axial force component is supported by an additional bearing in a mirror image arrangement. Similar conditions are present in the cylindrical roller bearing NJ.

Axial deep groove ball bearing

The balls in the axial deep groove ball bearing in ➤ Figure only roll correctly if the bearing runs clearance-free and with adequate minimum load.

If the shaft is horizontal, a further adjustable bearing must be provided. This is particularly important in the case of high speeds. If the shaft is vertical, the opposing bearing can be omitted if the bearing is adjusted clearance-free by the load in all operating states.

Axial location of the bearing rings in bearings in an adjusted or floating bearing arrangement


= the means of location must support significant axial forces


Angular contact ball bearing


Cylindrical roller bearing NJ


Axial deep groove ball bearing

Examples of the axial fixing of bearing rings

Axial location of bearing rings

➤ Figure to ➤ Figure show possibilities for the location of bearing rings depending on the design of the bearing arrangement and the application.

Locating/non-locating bearing arrangement

Deep groove ball bearing and cylindrical roller bearing

➤ Figure shows the bearing arrangement of the shaft in an electric motor of medium power rating.

Locating bearing A

The locating bearing A is subjected not only to radial forces but also to axial forces of alternating direction. The axial forces are not very high and do not act in a shock type manner. For location of the deep groove ball bearing, rigid shoulders, covers, snap rings or other form fit elements are therefore normally used. The adjacent parts should require little production work and mounting and dismounting should be easy to perform.

Non-locating bearing B

The non-locating bearing B must support radial forces only. The outer ring is clamped between the snap ring and cover, while the inner ring has a tight fit on the shaft.

Axial location of deep groove ball bearing and cylindrical roller bearing

A = locating bearing

B = non-locating bearing


Deep groove ball bearing


Cylindrical roller bearing NU


Snap ring


Spacer ring


Cover

Locating/non-locating bearing arrangement

Tapered roller bearing pair and cylindrical roller bearing

The bearing arrangement of a pinion shaft shown in ➤ Figure is subjected to high, occasionally shock type radial and axial forces. Due to the hypoid tooth set, precise axial adjustment of the pinion against the crown gear and rigid guidance are necessary.

Locating bearing A

The locating bearing A is formed by the tapered roller bearing pair clamped from within. Since spacer rings are arranged between the inner rings, the shaft nut can be tightened to a certain torque without leading to bracing of the bearing arrangement. The axial position of the pinion relative to the crown gear is set by means of shims at the time of mounting.

Non-locating bearing B

The non-locating bearing B must support radial forces only. Due to the magnitude of the forces, both rings have tight fits. A snap ring in one annular slot of the outer ring securely prevents creep of the bearing to the left. The ribs of the bearing rings represent additional security against creep to the right. In order to prevent jamming of the bearing arrangement, the non-locating bearing must have axial clearance between the inner ring rib and the rollers.

Axial location of tapered roller bearing pair and cylindrical roller bearing

A = locating bearing

B = non-locating bearing


Pair of tapered roller bearings


Cylindrical roller bearing


Snap ring


Spacer ring


Shims


Shaft nut

Locating bearing arrangement

Cylindrical roller bearing and axial deep groove ball bearing

The locating bearing in ➤ Figure is subjected to high axial forces in both directions and the shaft must be guided axially clearance-free.

The shaft locating washer of the double direction axial deep groove ball bearing and the inner ring of the cylindrical roller bearing are axially clamped by means of an end washer. The axial deep groove ball bearing is adjusted clearance-free by means of the intermediate ring inserted with a fit.

Axial location of axial deep groove ball bearing and cylindrical roller bearing


Housing locating washer of axial deep groove ball bearing, double direction


Cylindrical roller bearing NU


Spacer ring


Intermediate ring inserted with fit


End washer


Shaft locating washer of axial deep groove ball bearing

Locating bearing arrangement

Spherical roller bearing

➤ Figure shows the locating bearing for a conveyor sheave. In order that the bearing can be mounted and dismounted with ease, a withdrawal sleeve is used to locate the inner ring, which is pressed in using a hydraulic mounting method. The taper on the withdrawal sleeve is self-retaining. The end cap serves as a retainer only.

Axial location of spherical roller bearing with withdrawal sleeve


Spherical roller bearing


Cover


Withdrawal sleeve


End cap


Spacer bush with labyrinth passages

Locating bearing arrangement for vertical shaft

Radial deep groove ball bearing and axial deep groove ball bearing

The vertical shaft in ➤ Figure is radially guided by a radial deep groove ball bearing and axially supported by an axial deep groove ball bearing. The snap ring functions with the disc spring to give preload and prevent lift-off when the working pressure is not directed downwards. There is some axial clearance between the disc spring when pressed flat and the snap ring. This gives easier mounting of the snap ring.

Axial location of an axial and radial deep groove ball bearing with a vertical shaft


Radial deep groove ball bearing


Axial deep groove ball bearing


Snap ring


Disc spring

Non-locating bearing arrangement

Spherical roller bearing, location by adapter sleeve

The locating bearing in ➤ Figure must support high radial loads. When the adapter sleeve is tightened, this gives the bearing on the smooth shaft a tight fit, which prevents axial creep.

Axial location of spherical roller bearing with adapter sleeve


Spherical roller bearing


Locknut with tab washer


Adapter sleeve

Adjusted bearing arrangement

Tapered roller bearing pair, bearings in O arrangement, outer rings with tight fit

In wheel bearing arrangements with a rotating outer ring in accordance with ➤ Figure, not only are high radial and axial forces present but tilting moments also occur. The outer rings have a tight fit. In these sorts of hub bearing arrangements, this is important due to the circumferential load acting on the outer rings. The axial clearance of the bearing group is set by means of the fixing nut, where the loosely fitted inner ring of the outer bearing undergoes displacement.

Axial location of tapered roller bearing pair

H = support spacing


Tapered roller bearing pair,

O arrangement


Fixing nut

Adjusted bearing arrangement with spring washer

Deep groove ball bearings

The example in ➤ Figure shows a bearing arrangement that is commonly used in small electric motors. The bearings are not subjected to high loads, the speed is in the moderate range. The radial load is small and only guidance forces must be supported in an axial direction.

Inner rings with tight fit, outer rings with sliding seat, bearings adjusted by means of spring preload

The inner rings of the deep groove ball bearings have a tight fit on the journal and are abutted on the shaft shoulders. The outer rings have a sliding seat. A spring washer is fitted between the outer ring of the right hand bearing and the cover collar. The bearings are axially adjusted by the tensioned springs. This achieves particularly smooth running.

Floating bearing arrangement

Spherical roller bearings

➤ Figure shows the bearing arrangement of a heavy support roller. The bearings are subjected to high radial loads. In addition, a frictional force acts axially on the outside surface of the support roller. Close axial guidance is not required and, as a result, a floating bearing arrangement can be selected. In the course of this, the lateral movement of the outer rings is restricted by the contact in the housing. Both housings are split. The axial displacement distance s can be measured with the upper section removed.

Axial location of two spherical roller bearings

s = axial displacement distance


Spherical roller bearing


Cover


Spacer bush with labyrinth passages

Raceways with direct bearing arrangement

The raceways must be produced as a rolling bearing raceway

In rolling bearings without an inner ring, the rolling elements run directly on the shaft, while in bearings without an outer ring they run directly in the housing bore. The shaft and/or housing bore must therefore be produced as a rolling bearing raceway; steels, surface hardness and hardening depth ➤ link.

The raceways must be free of waviness and precision machined (grinding and honing); for design of raceways see product chapter.

The fits have a major influence on the bearing clearance

The shaft and housing fits have a considerable influence on the bearing and operating clearance of the rolling bearing; this must be taken into consideration in determining the tolerances.

Steels for the raceways

Through hardening steels

Through hardening steels in accordance with ISO 683-17 (e. g. 100Cr6) are suitable as materials for rolling bearing raceways in direct bearing arrangements. These can also be surface layer hardened.

Case hardening steels

Case hardening steels must conform to DIN EN ISO 683-17 (e. g. 17MnCr5, 18CrNiMo7-6) or EN 10084 (e. g. 16MnCr5).

Steels for induction surface layer hardening

For flame and induction hardening, steels to DIN EN ISO 683-17 must be used (e. g. C56E2, 43CrMo4) or DIN 17212 (e. g. Cf53).

Surface hardness and hardening depth of raceways

Nominal surface hardness: ≧ 670 HV

The hardness values apply to raceways, axial washers and shaft shoulders. Steels hardened by means of case, flame or induction hardening must have a surface hardness of 670 HV to 840 HV and an adequate hardening depth CHD or SHD.

Determining CHD and SHD

The requisite case hardening depth CHD for case hardening steels is determined in accordance with ➤ Equation, while the requisite surface hardening depth SHD for steels for induction surface layer hardening is determined in accordance with ➤ Equation.

Nominal hardening depth ≧ 0,3 mm

In accordance with DIN EN ISO 15787:2010, the hardening depth is the depth of the hardened surface zone at which there is still a hardness of 550 HV1. It is measured on the finish ground shaft and must correspond to the stated values, but must in any case be ≧ 0,3 mm.

Determining the case hardening depth

Approximation value for case hardening depth

An approximation value for determining the minimum hardness depth can be found in ➤ Equation. The reference value for the load present is the equivalent stress in accordance with the distortion energy hypothesis (DEH) as a function of the rolling element diameter Dw and the magnitude of the load.

Case hardening depth


Legend

CHD mm

Case hardening depth

Dw mm

Rolling element diameter


The local hardness must always be above the local requisite hardness, which can be calculated from the equivalent stress.

Case hardening depth and hardness profile

HV = hardness according to Vickers

z = depth under the contact surface


Requisite hardness (equivalent stress profile)


Actual hardness profile

Determining the surface hardening depth

For the calculation of the surface hardening depth SHD ➤ Equation applies.

Surface hardening depth


Legend

SHD mm

Surface hardening depth

Dw mm

Rolling element diameter

Rp0,2 N/mm2

Yield point of base material

Raceway hardness is less than 670 HV

If the raceway fulfils the requirements for rolling bearing materials but its hardness value is less than 670 HV (58 HRC), the load on the bearing arrangement cannot be as high as the full load carrying capacity of the bearing. In order to determine the load carrying capacity, the basic dynamic load rating C of the bearings must be multiplied by the reduction factor fH and the basic static load rating C0r by the reduction factor fH0 ➤ Figure and ➤ Figure.

Dynamic hardness factor at reduced hardness of raceways

fH = dynamic hardness factor

HV, HRC = surface hardness

Static hardness factor at reduced hardness of raceways

fH0 = static hardness factor

HV, HRC = surface hardness


Roller


Ball