Inhaltsverzeichnis

  • Crossed roller bearings
    • Bearing design
      • Crossed roller bearings SX are compact locating bearings with high axial rigidity
      • Also available in a corrosion-resistant design
      • Permissible circumferential velocities
    • Load carrying capacity
      • Suitable for axial loads in both directions, radial loads and tilting moment loads
    • Angular adjustment facility
      • Lubrication
        • Grease or oil lubrication is possible
        • Grease lubrication
        • Oil lubrication
      • Sealing
        • Provide seals in the adjacent construction
        • Schaeffler seal profiles
      • Speeds
        • Limiting speeds in the product tables
      • Noise
        • Schaeffler Noise Index
      • Temperature range
        • Limiting values
      • Cages
        • The rollers are guided by plastic spacers
      • Internal clearance
      • Dimensions, tolerances
        • Dimension standards
        • Tolerances
      • Suffixes
        • Suffixes and corresponding descriptions
      • Structure of bearing designation
        • Example
      • Dimensioning
        • Static load carrying capacity
        • Checking the static load carrying capacity
        • Dynamic load carrying capacity
        • Determining the basic rating life
        • Determining the load carrying capacity of the fixing screws
        • Static limiting load diagram for fixing screws – example
        • Checking the static load carrying capacity of the screws
        • Checking the dynamic load carrying capacity of the screws
      • Minimum load
        • In order to prevent damage due to slippage, a minimum load is required
      • Design of bearing arrangements
        • The design of the adjacent construction has a considerable influence on the function of the bearings
        • Shaft and housing tolerances
        • Location using clamping rings
        • Fixing screws
        • Securing of screws
      • Mounting and dismounting
        • Mounting of crossed roller bearings
        • Checking the function
      • Further information

      Crossed roller bearings

      Crossed roller bearings  SX :

      • are suitable, due to their high running accuracy, as bearings for high precision applications (such as those in robots, machine tools, handling systems, precision mechanical and medical devices, vehicle components)
        • correspond in their main dimensions to the ISO dimension series 18 with very small section height
          • can support axial forces in both directions, radial loads, tilting moments and any combination of loads ➤ section
            • usually allow designs with two bearing positions to be replaced by one bearing position ➤ Figure
              • are very rigid (they can be supplied with normal clearance, clearance‑free or preloaded)
                • are suitable for supported and suspended loads
                  • are always a good choice for a technically and economically leading bearing solution if compact and easy-to-fit rolling bearings with high tilting moment carrying capacity and rigidity, with uniform running free from stick-slip, low rotational resistance as well as high axial and radial runout accuracy are required in only one bearing position.

                    For an overview of other product-specific features, see the Matrix for bearing preselection.

                    Comparison: bearing arrangement with two bearing positions/ bearing arrangement with a crossed roller bearing SX

                    Bearing design

                    Crossed roller bearings SX are compact locating bearings with high axial rigidity

                    Crossed roller bearings SX are bearings for high precision applications, whose main dimensions correspond to the ISO dimension series 18 with very small section height in accordance with DIN 616. They comprise outer rings, inner rings, rolling elements and plastic spacers. The outer ring is split in the circumferential direction and is held together by three sheet metal retaining rings ➤ Figure. The cylindrical rollers correspond to DIN 5402 and are in an X arrangement with each other on the raceways. The bearings are very rigid, have high running accuracy and are supplied with normal clearance, low clearance or preload. Bearings with preload have the suffix VSP, while bearings with low clearance have the suffix RL0 ➤ Table. The bearing outer rings are easily fixed to the adjacent construction using clamping rings ➤ link.

                    Also available in a corrosion-resistant design

                    For applications requiring high corrosion protection, the bearings are also available in a corrosion-resistant design with the special coating Corrotect.

                    Crossed roller bearing SX

                    Permissible circumferential velocities

                    Influencing factors

                    The possible circumferential velocity is dependent on the bearing (normal clearance or preloaded) and on the lubrication (grease or oil) ➤ Table.

                    Permissible circumferential velocities

                    Normal clearance

                    Preload

                    Circumferential velocity

                    Oil lubrication

                    ‒

                    up to 8 m/s (n  ·  DM = 152 800)

                    Grease lubrication

                    ‒

                    up to 4 m/s (n  ·  DM =  76 400)

                    ‒

                    Oil lubrication

                    up to 4 m/s (n  ·  DM =  76 400)

                    ‒

                    Grease lubrication

                    up to 2 m/s (n  ·  DM =  38 200)

                    DM = rolling element pitch circle diameter

                    Load carrying capacity

                    Suitable for axial loads in both directions, radial loads and tilting moment loads

                    Due to the X arrangement of the cylindrical rollers, the bearings can support axial forces in both directions, radial loads, tilting moment loads and any combination of loads by means of a single bearing position ➤ Figure. As a result, it is generally possible to reduce conventional bearing arrangements comprising two bearing positions (bearing arrangement with one radial and one axial bearing) to one bearing position ➤ Figure and ➤ Figure. This reduces the work required and the costs for the design of the adjacent construction (only one bearing position is processed) and considerably reduces the mounting of the bearings (there is no requirement for the matching of two bearings to each other).

                    Conventional bearing arrangement with two bearing positions
                    Optimised bearing arrangement with one crossed roller bearing

                    Angular adjustment facility

                    Crossed roller bearings SX cannot be used for the compensation of misalignments. These bearings are precision bearings for high precision applications. In order to ensure their correct function, it is essential that the specifications for design of the adjacent construction are observed ➤ section. Skewing of the bearing rings increases the running noise, places increased strain on the plastic spacers, has a negative effect on the running accuracy and a highly detrimental influence on the operating life of the bearings.

                    Lubrication

                    Grease or oil lubrication is possible

                    The bearings are greased as standard but can alternatively be lubricated with oil. The decisive factors in determining the type of lubrication and the requisite lubricant quantity are:

                    • the size of the bearing
                      • the design of the bearing environment
                        • the lubricant feeds
                          • the operating conditions.

                            If there is any uncertainty as to whether the lubricant or type of lubrication is suitable for a particular application, please consult Schaeffler or the lubricant manufacturer respectively.

                            Grease lubrication

                            Suitable greases

                            If the bearing is to be lubricated with grease, a high quality lithium soap grease to DIN 51825–KP2N–20 is suitable, for example Arcanol Load150 or Load220.

                            Lubrication intervals

                            Influences on the lubrication interval

                            The lubrication intervals are essentially dependent on:

                            • the operating conditions
                              • the environmental influences such as contamination, water, etc.
                                • the type of bearings.

                                  Precise lubrication intervals can only be determined by means of tests under the specific application conditions. The observation period selected must be sufficiently long and the condition of the grease must be checked at regular intervals.

                                  Grease operating life

                                  If relubrication is not possible, the grease operating life becomes the decisive factor. Based on experience, the guide value for the grease operating life in the majority of applications is higher by a factor of 2 than the guide value for the lubrication interval. At operating temperatures above +70 °C, the lubrication interval and therefore the grease operating life are reduced. In order to ensure operational reliability, the grease operating life should not exceed 3 years.

                                  Oil lubrication

                                  Selection of the oil

                                  A lubricant film which is capable of supporting loads must form in the contact zones between the rolling elements and the raceway. Depending on the operating speed, the oil at operating temperature must have at least the nominal viscosity ν 1 . The guide value for ν 1 is dependent on the mean bearing diameter dM and the speed.

                                  Influence of temperature on viscosity

                                  As the temperature increases, the viscosity of the oil decreases. When selecting the viscosity, the lower operating temperature must also be taken into consideration. With increasing viscosity, the flowability of the lubricant is reduced. As a result, the level of power losses will increase.

                                  Suitable oils

                                  For oil lubrication, suitable oils are type CLP to DIN 1517 or HLP to DIN 51524 of the viscosity classes ISO VG 10 to 100.

                                  With oil lubrication, oil change intervals must be observed

                                  At higher temperatures, aged oil and additives in the oil can impair the operating life of the plastic used for the spacers. Stipulated oil change intervals must therefore be observed.

                                  Sealing

                                  Provide seals in the adjacent construction

                                  Crossed roller bearings SX are not sealed. As a result, sealing of the bearing position must be carried out in the adjacent construction. This must reliably prevent:

                                  • moisture and contaminants from entering the bearing
                                    • the egress of lubricant from the bearing.

                                      Schaeffler seal profiles

                                      Material by the metre for radial and/or axial sealing of the bearing position

                                      For sealing of the bearing position in the adjacent construction, Schaeffler supplies various seal profiles by the metre ➤ Figure. These profiles are intended for axial and/or radial sealing and – depending on the seal profile – fulfil a wide range of requirements (for example: under normal requirements for sealing, under heavy contamination, for low frictional torque, if only limited space is available, for sealing of fluids, at low speeds or under swivel operation). In addition to the seal profiles with a radial or axial sealing effect respectively, double direction profiles (with both axial and radial sealing effect) are also available. Mounting drawings can be requested for the individual seal profiles.

                                      The seal profiles are not suitable for applications that require leakage-free operation; this applies not only to oil but also to grease lubrication. If leakage losses are unacceptable, measures such as rotary shaft seals can be used. The area around the bearing seal must be designed such that the seal profiles are not damaged during operation.

                                      Seal profiles – example
                                      Seal profile material

                                      The standard material for the profiles is the synthetic elastomer NBR 70. This material has good resistance to oil and grease as well as good wear resistance. Operating temperature of seal profiles ➤ Table.

                                      For further information on the seal profiles, please contact Schaeffler.

                                      Speeds

                                      Limiting speeds in the product tables

                                      Rolling bearings cannot rotate at unspecified high speeds, but are generally restricted by the operating temperature that is permissible in relation to the lubricant and the material of the bearing parts ➤ section. The product tables give the kinematic limiting speeds nG oil and nG grease for the bearings.

                                      The limiting speeds nG oil and nG grease are the kinematically permissible speeds for a bearing and apply to oil and grease lubrication respectively. Even under favourable mounting and operating conditions, these speeds must not be exceeded without prior consultation with Schaeffler.

                                      Noise

                                      Schaeffler Noise Index

                                      The Schaeffler Noise Index (SGI) is not yet available for this bearing type. The data for these bearing series will be introduced and updated in stages.

                                      Temperature range

                                      Limiting values

                                      The operating temperature of the bearings is limited by:

                                      • the dimensional stability of the bearing rings and cylindrical rollers
                                        • the material of the plastic spacers
                                          • the lubricant
                                            • the seal material in the adjacent construction.

                                              Possible operating temperatures of the bearings ➤ Table.

                                              Permissible temperature ranges

                                              Operating temperature

                                              Crossed roller bearings

                                              Schaeffler seal profiles

                                              –30 °C to +100 °C

                                              –40 °C to +80 °C

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

                                              Cages

                                              The rollers are guided by plastic spacers

                                              In the crossed roller bearings SX, the rolling elements are separated from each other and guided not by typical rolling bearing cages but by plastic spacers ➤ Figure. The plastic selected and the design of the running surfaces for the cylindrical rollers give low-friction running of the bearings.

                                              Internal clearance

                                              The crossed roller bearings are available:

                                              • with normal clearance (radial and axial clearance)
                                                • with low clearance (radial clearance/preload)
                                                  • with preload VSP (preload min. and max.).

                                                    Dimensions, tolerances

                                                    The dimensions of special bearings (F../Z..) may deviate from the standard.

                                                    Dimension standards

                                                    The main dimensions of crossed roller bearings correspond to dimension series 18 in accordance with DIN 616.

                                                    Tolerances

                                                    The dimensional and running tolerances are based on DIN 620-2 and DIN 620-3 and are in the range P6 and P5.

                                                    Suffixes

                                                    Suffixes describe the design and features of a bearing in more detail.

                                                    Suffixes and corresponding descriptions

                                                    Suffix

                                                    Description of suffix

                                                    RR

                                                    Corrosion-resistant design,
                                                    with Corrotect coating

                                                    Special design,
                                                    available by agreement

                                                    RL0

                                                    Low clearance

                                                    Standard

                                                    VSP

                                                    Preloaded

                                                    Special design,
                                                    available by agreement

                                                    VSP+PRL50

                                                    Preloaded, axial and radial runout tolerance restricted by 50%

                                                    Special design,
                                                    available by agreement

                                                    Structure of bearing designation

                                                    With medias interchange, equivalent Schaeffler bearing designations can be determined for bearing designations from other rolling bearing manufacturers http://www.schaeffler.de/std/1B69.

                                                    Example

                                                    The designation of bearings follows a set model ➤ Figure.

                                                    Crossed roller bearing SX, low clearance: designation structure

                                                    Dimensioning

                                                    Static load carrying capacity

                                                    For bearings under static loading, the static load carrying capacity applies

                                                    Crossed roller bearings that undergo rotary motion only infrequently, undergo slow swivel motion, rotate only slowly or are subjected to load while stationary are dimensioned on the basis of their static load carrying capacity. The size of a statically loaded bearing can therefore be checked in approximate terms using the basic static load ratings C0 and the static limiting load diagrams.

                                                    Checking the static load carrying capacity

                                                    It can be checked in approximate terms if the correct load arrangement is present and all the requirements relating to clamping rings, location, mounting and lubrication are fulfilled ➤ Figure.

                                                    Where load arrangements are more complex or there are variations from the conditions, please contact us.

                                                    Load arrangement

                                                    In order to check the static load carrying capacity, the following equivalent static operating values must be determined:

                                                    • the equivalent static bearing load F0q
                                                      • the equivalent static tilting moment load M0q .

                                                        Checking is possible for applications with or without radial load.

                                                        Determining the equivalent static bearing load without radial load
                                                        In the presence of axial and tilting moment loads only ➤ Equation and ➤ Equation:

                                                        Equivalent axial bearing load (static)

                                                        Equivalent tilting moment load (static)

                                                        Legend

                                                        F0q kN

                                                        Equivalent axial bearing load (static)

                                                        F0a kN

                                                        Axial static bearing load

                                                        fA

                                                        Application factor ➤ Table

                                                        fS

                                                        Factor for additional safety ➤ link

                                                        M0q kNm

                                                        Equivalent tilting moment load (static)

                                                        M0k kNm

                                                        Static tilting moment load.

                                                        The values for F0q and M0q are used to determine the load point in the static limiting load diagram for the raceway.

                                                        In addition to the raceway, the dimensioning of the fixing screws must also be checked.

                                                        The static limiting load diagrams for the raceway and the fixing screws are indicated in the product tables.

                                                        The load point must lie under the raceway curve, otherwise the bearing is not adequately dimensioned.

                                                        Determining the equivalent static bearing load with radial load

                                                        Radial loads can only be taken into consideration if the radial load F0r is smaller than the basic static radial load rating C0r .

                                                        The equivalent static bearing load with radial load is determined as follows:

                                                        • Calculate the parameter for the load eccentricity ε according to ➤ Equation
                                                          • Determine the static radial load factor f0r . In this case:
                                                            • determine the ratio F0r/F0a in ➤ Figure or ➤ Figure respectively
                                                            • based on the ratio F0r/F0a and ε, determine the static radial load factor f0r from ➤ Figure or ➤ Figure respectively
                                                            • Determine the application factor fA ➤ Table and, where necessary, the safety factor fS
                                                              • Calculate the equivalent axial bearing load F0q and the equivalent tilting moment load M0q using the equations ➤ Equation and ➤ Equation
                                                                • Using the values for F0q and M0q, determine the load point in the static limiting load diagram for the raceway.

                                                                  The load point must lie under the raceway curve, otherwise the bearing is not adequately dimensioned.

                                                                  Load eccentricity parameter

                                                                  Equivalent bearing load (static)

                                                                  Equivalent tilting moment load (static)

                                                                  Legend

                                                                  ε

                                                                  Load eccentricity parameter

                                                                  M0k  kNm

                                                                  Static tilting moment load

                                                                  F0a  kN

                                                                  Axial static bearing load

                                                                  DM  mm

                                                                  Rolling element pitch circle diameter

                                                                  F0q  kN

                                                                  Equivalent bearing load (static)

                                                                  fA

                                                                  Application factor ➤ Table

                                                                  fS

                                                                  Factor for additional safety ➤ link

                                                                  f0r

                                                                  Static radial load factor ➤ Figure or ➤ Figure

                                                                  M0q kNm

                                                                  Equivalent tilting moment load (static).

                                                                  Static radial load factor
                                                                  Static radial load factor
                                                                  Application factors

                                                                  The application factors fA are empirical values obtained in practice ➤ Table. They take account of the most important requirements, such as the type and severity of operation, rigidity and running accuracy. If the precise requirements of an application are known, the values may be altered accordingly.

                                                                  Application factors < 1 must not be used.

                                                                  A large proportion of applications can be statically calculated using the factor 1, for example in the case of bearings for gearboxes and rotary tables.

                                                                  In addition to static calculation, the rating life should also always be checked ➤ link.

                                                                  Application factors fA

                                                                  Application

                                                                  Operating and
                                                                  requirement criteria

                                                                  Application factor

                                                                  fA

                                                                  Robots

                                                                  Rigidity

                                                                  1,25

                                                                  Antennae

                                                                  Accuracy

                                                                  1,5

                                                                  Machine tools

                                                                  Accuracy

                                                                  1,5

                                                                  Metrology

                                                                  Smooth running

                                                                  2

                                                                  Medical equipment

                                                                  Smooth running

                                                                  1,5

                                                                  Safety factors

                                                                  The factor for additional safety fS is 1.

                                                                  It is not normally necessary to factor in any additional safety in calculation.

                                                                  In special cases, such as approval specifications, internal specifications, requirements stipulated by inspection bodies etc., the appropriate safety factors must be applied.

                                                                  Calculation example

                                                                  The static load carrying capacity of the crossed roller bearing SX011860 is to be checked.

                                                                  Given

                                                                    Static bearing load (axial)

                                                                    F0a

                                                                    =

                                                                    70 kN

                                                                    Static bearing load (radial)

                                                                    F0r

                                                                    =

                                                                    17,5 kN

                                                                    Static tilting moment load

                                                                    M0k

                                                                    =

                                                                    22,5 kNm

                                                                    Rolling element pitch circle diameter

                                                                    DM

                                                                    =

                                                                    340 mm

                                                                    Application factor

                                                                    fA

                                                                    =

                                                                    1,25

                                                                    Safety factor

                                                                    fS

                                                                    =

                                                                    1

                                                                  Required

                                                                  Static load carrying capacity of the bearing

                                                                  Solution

                                                                  Load eccentricity parameter

                                                                  Legend

                                                                  ε

                                                                  Load eccentricity parameter

                                                                  M0k  kNm

                                                                  Static tilting moment load

                                                                  F0a  kN

                                                                  Static bearing load (axial)

                                                                  DM  mm

                                                                  Rolling element pitch circle diameter

                                                                  F0r  kN

                                                                  Static bearing load (radial)

                                                                  f0r

                                                                  Static radial load factor ➤ Figure or ➤ Figure.

                                                                  Equivalent bearing load (static)

                                                                  Legend

                                                                  F0q  kN

                                                                  Equivalent bearing load (static)

                                                                  F0a  kN

                                                                  Static bearing load (axial)

                                                                  fA

                                                                  Application factor

                                                                  fS

                                                                  Factor for additional safety.

                                                                  Equivalent tilting moment load (static)

                                                                  Legend

                                                                  M0q  kNm

                                                                  Equivalent tilting moment load (static)

                                                                  M0k  kNm

                                                                  Static tilting moment load

                                                                  fA

                                                                  Application factor

                                                                  fS

                                                                  Factor for additional safety.

                                                                  Determining the load point in the static limiting load diagram – checking the static load carrying capacity

                                                                  Using the values for F0q and M0q, the load point in the static limiting load diagrams for the raceway and fixing screws is determined ➤ Figure and ➤ Figure.

                                                                  The load point is below the raceway and screw curves. The bearing is adequately dimensioned and thus suitable for the application.

                                                                  Static limiting load diagram for raceway – compressive load
                                                                  Static limiting load diagram for fixing screws – compressive load

                                                                  Dynamic load carrying capacity

                                                                  For bearings under dynamic loading, the dynamic load carrying capacity applies

                                                                  Dynamically loaded crossed roller bearings, i. e. bearings that undergo predominantly rotary motion, are dimensioned in accordance with their dynamic load carrying capacity. The size of a dynamically loaded bearing can therefore be checked in approximate terms using the basic dynamic load ratings C and the basic rating life L or Lh.

                                                                  Determining the basic rating life

                                                                  The life formulae for L and Lh are only valid:

                                                                  • with a load arrangement according to ➤ Figure
                                                                    • if all the requirements are fulfilled in relation to location (the bearing rings must be rigid or firmly connected to the adjacent construction), mounting, lubrication and sealing
                                                                      • if the load and speed can be regarded as constant during operation. If the load and speed are not constant, equivalent operating values can be determined that will result in the same fatigue conditions as the actual loads
                                                                        • if the load ratio is Fr/Fa ≦ 8.

                                                                          For more complex load arrangements, if a ratio Fr/Fa > 8 is present or there are variations from the specified conditions, please contact us.

                                                                          Load arrangement
                                                                          Determining the basic rating life for bearings subjected to combined loads

                                                                          For bearings subjected to combined loads, in other words bearings with axial, radial and tilting moment loads, the rating life L or Lh is determined as follows:

                                                                          • Determine the ratio of the radial dynamic bearing load Fr to the axial dynamic bearing load Fa (Fr/Fa)
                                                                            • Calculate the load eccentricity parameter ε ➤ Equation
                                                                              • Using the values for ε and the ratio Fr/Fa, determine the dynamic load factor kF ➤ Figure
                                                                                • Calculate the equivalent dynamic axial bearing load Pa = kF  ·  Fa ➤ Equation
                                                                                  • Enter the equivalent dynamic axial bearing load Pa and the basic dynamic axial load rating Ca in the rating life equations L or Lh respectively and calculate the rating life ➤ Equation and ➤ Equation
                                                                                  • If swivel operation is present, enter the operating speed n determined in the rating life equation Lh ➤ Equation.

                                                                                    Load eccentricity parameter

                                                                                    Equivalent dynamic axial bearing load

                                                                                    Basic rating life in millions of revolutions

                                                                                    Basic rating life in operating hours

                                                                                    Operating speed

                                                                                    Dynamic load factor
                                                                                    Determining the basic rating life for bearings subjected to radial loads only

                                                                                    For slewing rings subjected to radial loads only, the following values are entered in the rating life formulae L and Lh:

                                                                                    • Pr = Fr
                                                                                      • the basic dynamic radial load rating Cr .

                                                                                        Basic rating life in millions of revolutions

                                                                                        Basic rating life in operating hours

                                                                                        Legend

                                                                                        ε

                                                                                        Load eccentricity parameter

                                                                                        Mk kNm

                                                                                        Dynamic tilting moment load

                                                                                        Fa kN

                                                                                        Axial dynamic bearing load

                                                                                        DM mm

                                                                                        Rolling element pitch circle diameter

                                                                                        Pa kN

                                                                                        Equivalent dynamic axial bearing load. For bearings subjected to radial load only, enter Pr

                                                                                        kF

                                                                                        Dynamic load factor ➤ Figure

                                                                                        L10 106 

                                                                                        Basic rating life in millions of revolutions

                                                                                        Ca, Cr kN

                                                                                        Basic axial or radial dynamic load rating. For bearings subjected to radial load only, enter Cr

                                                                                        p

                                                                                        Life exponent for crossed roller bearings: p = 10/3

                                                                                        L10h h

                                                                                        Basic rating life in operating hours

                                                                                        n min–1

                                                                                        Operating speed

                                                                                        nosc min–1

                                                                                        Frequency of oscillating motion

                                                                                        γ  °

                                                                                        Half of swivel angle

                                                                                        Pr kN

                                                                                        Equivalent dynamic radial bearing load

                                                                                        Fr kN

                                                                                        Radial dynamic bearing load.

                                                                                        Calculation example

                                                                                        For the crossed roller bearing SX011820, the basic rating life L in millions of revolutions is to be checked.

                                                                                        Given

                                                                                          Crossed roller bearing

                                                                                          SX011820

                                                                                          Rolling element pitch circle diameter

                                                                                          DM

                                                                                          =

                                                                                          112 mm

                                                                                          Basic dynamic load rating (axial)

                                                                                          Ca

                                                                                          =

                                                                                          28 kN

                                                                                          Life exponent for crossed roller bearings

                                                                                          p

                                                                                          =

                                                                                          10/3

                                                                                          Dynamic bearing load (axial)

                                                                                          Fa

                                                                                          =

                                                                                          20 kN

                                                                                          Dynamic bearing load (radial)

                                                                                          Fr

                                                                                          =

                                                                                          4 kN

                                                                                          Dynamic tilting moment load

                                                                                          Mk

                                                                                          =

                                                                                          1 kNm

                                                                                        Required

                                                                                        Basic rating life L10 in millions of revolutions

                                                                                        Solution

                                                                                        Load eccentricity parameter

                                                                                        Legend

                                                                                        ε

                                                                                        Load eccentricity parameter

                                                                                        Mk  kNm

                                                                                        Dynamic tilting moment load

                                                                                        Fa  kN

                                                                                        Axial dynamic bearing load

                                                                                        DM  mm

                                                                                        Rolling element pitch circle diameter

                                                                                        Fr  kN

                                                                                        Radial dynamic bearing load

                                                                                        kF

                                                                                        Dynamic load factor ➤ Figure.

                                                                                        Equivalent bearing load (static)

                                                                                        Legend

                                                                                        Pa  kN

                                                                                        Equivalent dynamic axial bearing load.

                                                                                        For bearings subjected to radial load only, enter Pr

                                                                                        kF

                                                                                        Dynamic load factor ➤ Figure

                                                                                        Fa  kN

                                                                                        Axial dynamic bearing load.

                                                                                        Basic rating life in million revolutions

                                                                                        Legend

                                                                                        L10  106

                                                                                        Basic rating life in millions of revolutions

                                                                                        For bearings subjected to radial load only, enter Pr

                                                                                        Ca, Cr  kN

                                                                                        Basic axial or radial dynamic load rating

                                                                                        Pa  kN

                                                                                        Equivalent dynamic axial bearing load.

                                                                                        For bearings subjected to radial load only, enter Pr

                                                                                        p

                                                                                        Life exponent for crossed roller bearings: p = 10/3.

                                                                                        Dynamic load factor kF for crossed roller bearings

                                                                                        Determining the load carrying capacity of the fixing screws

                                                                                        In addition to the raceway, the load carrying capacity of the fixing screws must also be checked. This is based on the information in ➤ link.

                                                                                        The load carrying capacity of the fixing screws can be checked if the following conditions are fulfilled:

                                                                                        • the criteria according to ➤ link
                                                                                          • the screws are tightened as specified using a torque wrench
                                                                                          • screw tightening factor αA = 1,6
                                                                                          • tightening torques ➤ Table to ➤ Table
                                                                                          • the permissible contact pressure is not exceeded
                                                                                            • screws of the recommended size, quantity and grade are used.
                                                                                              Indicator of load carrying capacity

                                                                                              The load carrying capacity of the screws is described by:

                                                                                              • the curves in the static limiting load diagrams for fixing screws in the product tables
                                                                                                • the maximum permissible radial load Fr per (friction locking).

                                                                                                  The screw curves are shown in the static limiting load diagrams for fixing screws. The curves are based on screws of grade 10.9, tightened to 90% of their proof stress, including the torsion content.

                                                                                                  If screws of grade 8.8 or 12.9 are used, the equivalent static loads F0q and M0q, ➤ link, must be converted using the following factors:

                                                                                                  • grade   8.8 (F0q  ·  1,65, M0q ·  1,65)
                                                                                                    • grade  12.9 (F0q ·  0,8, M0q ·  0,8).

                                                                                                      Static limiting load diagram for fixing screws – example

                                                                                                      Static limiting load diagram for fixing screws – example for crossed roller bearing SX011860

                                                                                                      Checking the static load carrying capacity of the screws

                                                                                                      The static load carrying capacity of the screw is limited by its proof stress.

                                                                                                      For applications with and without radial load

                                                                                                      The equivalent static bearing loads F0q and M0q must be determined.

                                                                                                      Using the values F0q and M0q, the load point is then determined in the static limiting load diagram for fixing screws.

                                                                                                      The load point must be below the appropriate screw curve.

                                                                                                      Radial load and static load carrying capacity of the screws

                                                                                                      If radial loads occur in uncentred bearing rings, the screw connections must prevent displacement of the bearing rings on the adjacent construction.

                                                                                                      In order to check this:

                                                                                                      • multiply the radial bearing load by an application factor fA ➤ Table
                                                                                                        • compare the values determined with the maximum permissible radial load Fr per .

                                                                                                          The maximum radial load Fr per on the fixing screws is dependent on their friction locking and not on the radial load carrying capacity of the bearing.

                                                                                                          If the radial load on the bearing is higher than the friction locking of the fixing screws or very high radial loads are present (Fr/Fa > 4), please contact us.

                                                                                                          Checking the dynamic load carrying capacity of the screws

                                                                                                          The dynamic load carrying capacity of the screws corresponds to the fatigue strength of the screw.

                                                                                                          Dynamic load carrying capacity

                                                                                                          Based on the dynamic loads present, the equivalent loads F0q and M0q are determined.

                                                                                                          Instead of the application factor fA , the operating load must always be increased by the following factor:

                                                                                                          • grade  8.8 (factor 1,8),
                                                                                                            grade 10.9 (factor 1,6),
                                                                                                            grade 12.9 (factor 1,5).

                                                                                                            The load carrying capacity must then be checked in the static limiting load diagram for the fixing screws.

                                                                                                            The load point must be below the appropriate screw curve.

                                                                                                            Minimum load

                                                                                                            In order to prevent damage due to slippage, a minimum load is required

                                                                                                            In order that no slippage occurs between the contact partners, the crossed roller bearings must be constantly subjected to a sufficiently high load. In most cases, however, the load is already sufficiently high due to the weight of the supported parts and the external forces.

                                                                                                            Design of bearing arrangements

                                                                                                            The design of the adjacent construction has a considerable influence on the function of the bearings

                                                                                                            Crossed roller bearings SX can support high loads. Due to the X arrangement of the cylindrical rollers, these bearings can support axial forces in both directions, radial loads, tilting moment loads and any combinations of loads. In order that these advantages can be utilised comprehensively, the adjacent construction must be designed so that it is appropriately rigid. The bearing rings must always be rigidly and uniformly supported over the circumference and width of the rings ➤ Figure.

                                                                                                            The adjacent construction must be designed only in accordance with the information in this section. Any deviations from the specifications, material strength and adjacent components will considerably reduce the load carrying capacity and operating life of the bearings.

                                                                                                            Uniform support of the bearing rings by the adjacent construction

                                                                                                            Shaft and housing tolerances

                                                                                                            For normal applications, the tolerance class K7 Ⓔ for the housing and h7 Ⓔ for the shaft are sufficient ➤ Table and ➤ Table.

                                                                                                            In precision applications, the bearing seat in the housing should be designed to tolerance class K6 Ⓔ and on the shaft to h6 Ⓔ ➤ Table and ➤ Table.

                                                                                                            Mounting tolerances for the shaft

                                                                                                            Nominal dimension

                                                                                                            di

                                                                                                            Tolerance classes

                                                                                                            mm

                                                                                                            >

                                                                                                            ≦

                                                                                                            h6

                                                                                                            h7

                                                                                                            Upper deviation

                                                                                                            Lower deviation

                                                                                                            Upper deviation

                                                                                                            Lower deviation

                                                                                                            μm

                                                                                                            μm

                                                                                                            μm

                                                                                                            μm

                                                                                                            65

                                                                                                            80

                                                                                                            0

                                                                                                            –19

                                                                                                            0

                                                                                                            –30

                                                                                                            80

                                                                                                            100

                                                                                                            0

                                                                                                            –22

                                                                                                            0

                                                                                                            –35

                                                                                                            100

                                                                                                            120

                                                                                                            0

                                                                                                            –22

                                                                                                            0

                                                                                                            –35

                                                                                                            120

                                                                                                            140

                                                                                                            0

                                                                                                            –25

                                                                                                            0

                                                                                                            –40

                                                                                                            140

                                                                                                            160

                                                                                                            0

                                                                                                            –25

                                                                                                            0

                                                                                                            –40

                                                                                                            160

                                                                                                            180

                                                                                                            0

                                                                                                            –25

                                                                                                            0

                                                                                                            –40

                                                                                                            continued ▼

                                                                                                            Mounting tolerances for the shaft

                                                                                                            Nominal dimension

                                                                                                            di

                                                                                                            Tolerance classes

                                                                                                            mm

                                                                                                            >

                                                                                                            ≦

                                                                                                            h6

                                                                                                            h7

                                                                                                            Upper deviation

                                                                                                            Lower deviation

                                                                                                            Upper deviation

                                                                                                            Lower deviation

                                                                                                            μm

                                                                                                            μm

                                                                                                            μm

                                                                                                            μm

                                                                                                            180

                                                                                                            200

                                                                                                            0

                                                                                                            –29

                                                                                                            0

                                                                                                            –46

                                                                                                            200

                                                                                                            225

                                                                                                            0

                                                                                                            –29

                                                                                                            0

                                                                                                            –46

                                                                                                            225

                                                                                                            250

                                                                                                            0

                                                                                                            –29

                                                                                                            0

                                                                                                            –46

                                                                                                            250

                                                                                                            280

                                                                                                            0

                                                                                                            –32

                                                                                                            0

                                                                                                            –52

                                                                                                            280

                                                                                                            315

                                                                                                            0

                                                                                                            –32

                                                                                                            0

                                                                                                            –52

                                                                                                            315

                                                                                                            355

                                                                                                            0

                                                                                                            –36

                                                                                                            0

                                                                                                            –57

                                                                                                            355

                                                                                                            400

                                                                                                            0

                                                                                                            –36

                                                                                                            0

                                                                                                            –57

                                                                                                            400

                                                                                                            450

                                                                                                            0

                                                                                                            –40

                                                                                                            0

                                                                                                            –63

                                                                                                            450

                                                                                                            500

                                                                                                            0

                                                                                                            –40

                                                                                                            0

                                                                                                            –63

                                                                                                            continued ▲

                                                                                                            Mounting tolerances for the housing bore

                                                                                                            Nominal dimension

                                                                                                            Da

                                                                                                            Tolerance classes

                                                                                                            mm

                                                                                                            >

                                                                                                            ≦

                                                                                                            K6

                                                                                                            K7

                                                                                                            Upper deviation

                                                                                                            Lower deviation

                                                                                                            Upper deviation

                                                                                                            Lower deviation

                                                                                                            μm

                                                                                                            μm

                                                                                                            μm

                                                                                                            μm

                                                                                                            80

                                                                                                            100

                                                                                                            +4

                                                                                                            –18

                                                                                                            +10

                                                                                                            –25

                                                                                                            100

                                                                                                            120

                                                                                                            +4

                                                                                                            –18

                                                                                                            +10

                                                                                                            –25

                                                                                                            120

                                                                                                            140

                                                                                                            +4

                                                                                                            –21

                                                                                                            +12

                                                                                                            –28

                                                                                                            140

                                                                                                            160

                                                                                                            +4

                                                                                                            –21

                                                                                                            +12

                                                                                                            –28

                                                                                                            160

                                                                                                            180

                                                                                                            +4

                                                                                                            –21

                                                                                                            +12

                                                                                                            –28

                                                                                                            180

                                                                                                            200

                                                                                                            +5

                                                                                                            –24

                                                                                                            +13

                                                                                                            –33

                                                                                                            200

                                                                                                            225

                                                                                                            +5

                                                                                                            –24

                                                                                                            +13

                                                                                                            –33

                                                                                                            225

                                                                                                            250

                                                                                                            +5

                                                                                                            –24

                                                                                                            +13

                                                                                                            –33

                                                                                                            250

                                                                                                            280

                                                                                                            +5

                                                                                                            –27

                                                                                                            +16

                                                                                                            –36

                                                                                                            280

                                                                                                            315

                                                                                                            +5

                                                                                                            –27

                                                                                                            +16

                                                                                                            –36

                                                                                                            315

                                                                                                            355

                                                                                                            +7

                                                                                                            –29

                                                                                                            +17

                                                                                                            –40

                                                                                                            355

                                                                                                            400

                                                                                                            +7

                                                                                                            –29

                                                                                                            +17

                                                                                                            –40

                                                                                                            400

                                                                                                            450

                                                                                                            +8

                                                                                                            –32

                                                                                                            +18

                                                                                                            –45

                                                                                                            450

                                                                                                            500

                                                                                                            +8

                                                                                                            –32

                                                                                                            +18

                                                                                                            –45

                                                                                                            500

                                                                                                            560

                                                                                                            0

                                                                                                            –44

                                                                                                            0

                                                                                                            –70

                                                                                                            560

                                                                                                            630

                                                                                                            0

                                                                                                            –44

                                                                                                            0

                                                                                                            –70

                                                                                                            Location using clamping rings

                                                                                                            For the location of crossed roller bearings SX, clamping rings have proved effective ➤ Figure.

                                                                                                            The bearing rings must always be rigidly and uniformly supported over the circumference and width of the rings.

                                                                                                            The thickness of the clamping rings and mounting flanges must not be less than the minimum thickness s.

                                                                                                            Counterbores to DIN 74, type J, for screws to DIN 6912 are permissible. For deeper counterbores, the thickness of the clamping ring s must be increased by the additional counterbore depth.

                                                                                                            Mounting dimensions ➤ Table and ➤ Figure . Minimum strength of clamping rings ➤ link .

                                                                                                            Bearing seat depth

                                                                                                            In order that the clamping rings retain the bearing securely, the bearing seat depth t must be in accordance with the specification ➤ Table and ➤ Figure.

                                                                                                            The depth of the bearing seat influences the bearing clearance and the rotational resistance.

                                                                                                            Bearings with preload (suffix VSP) have a considerably higher rotational resistance.

                                                                                                            If particular requirements for rotational resistance apply, the depth t must be produced to match the relevant height of the bearing ring. It has proved effective to tolerance the depth t to deviations that are the same as or further restricted compared to the dimension h in the product tables. For safety, internal tests should in any case be carried out.

                                                                                                            Minimum strength of clamping rings

                                                                                                            For screws of grade 10.9, the minimum strength under the screw heads or nuts must be 500 N/mm2 . Seating washers are not necessary for these screws.

                                                                                                            For fixing screws of grade 12.9, the minimum strength must not be less than 850 N/mm2 , otherwise quenched and tempered seating washers under the screw heads or quenched and tempered nuts must be used.

                                                                                                            Mounting dimensions

                                                                                                            Designation

                                                                                                            Mounting dimensions in mm

                                                                                                            di

                                                                                                            Da

                                                                                                            t

                                                                                                            s

                                                                                                            dRa

                                                                                                            dRi

                                                                                                            DRi

                                                                                                            DRa

                                                                                                            Li

                                                                                                            La

                                                                                                            h7

                                                                                                            (h6)

                                                                                                            K7

                                                                                                            (K6)

                                                                                                             

                                                                                                            min.

                                                                                                             

                                                                                                            max.

                                                                                                             

                                                                                                            min.

                                                                                                            SX011814

                                                                                                            70

                                                                                                            90

                                                                                                            10

                                                                                                            –0,005 –0,015

                                                                                                            8

                                                                                                            78

                                                                                                            42

                                                                                                            82

                                                                                                            118

                                                                                                            60

                                                                                                            100

                                                                                                            SX011818

                                                                                                            90

                                                                                                            115

                                                                                                            13

                                                                                                            –0,005 –0,020

                                                                                                            10

                                                                                                            100

                                                                                                            61

                                                                                                            104

                                                                                                            144

                                                                                                            80

                                                                                                            125

                                                                                                            SX011820

                                                                                                            100

                                                                                                            125

                                                                                                            13

                                                                                                            –0,005 –0,020

                                                                                                            10

                                                                                                            110

                                                                                                            71

                                                                                                            114

                                                                                                            154

                                                                                                            90

                                                                                                            135

                                                                                                            SX011824

                                                                                                            120

                                                                                                            150

                                                                                                            16

                                                                                                            –0,005 –0,025

                                                                                                            12

                                                                                                            132

                                                                                                            84

                                                                                                            138

                                                                                                            186

                                                                                                            108

                                                                                                            162

                                                                                                            SX011828

                                                                                                            140

                                                                                                            175

                                                                                                            18

                                                                                                            –0,005 –0,030

                                                                                                            14

                                                                                                            154

                                                                                                            94

                                                                                                            160

                                                                                                            221

                                                                                                            124

                                                                                                            191

                                                                                                            SX011832

                                                                                                            160

                                                                                                            200

                                                                                                            20

                                                                                                            –0,02 –0,05

                                                                                                            15

                                                                                                            177

                                                                                                            111

                                                                                                            183

                                                                                                            249

                                                                                                            144

                                                                                                            216

                                                                                                            SX011836

                                                                                                            180

                                                                                                            225

                                                                                                            22

                                                                                                            –0,02 –0,05

                                                                                                            17

                                                                                                            199

                                                                                                            121

                                                                                                            205

                                                                                                            284

                                                                                                            160

                                                                                                            245

                                                                                                            SX011840

                                                                                                            200

                                                                                                            250

                                                                                                            24

                                                                                                            –0,02 –0,06

                                                                                                            18

                                                                                                            221

                                                                                                            139

                                                                                                            229

                                                                                                            311

                                                                                                            180

                                                                                                            270

                                                                                                            SX011848

                                                                                                            240

                                                                                                            300

                                                                                                            28

                                                                                                            –0,02 –0,06

                                                                                                            21

                                                                                                            269

                                                                                                            166

                                                                                                            274

                                                                                                            374

                                                                                                            216

                                                                                                            324

                                                                                                            SX011860

                                                                                                            300

                                                                                                            380

                                                                                                            38

                                                                                                            –0,04 –0,10

                                                                                                            29

                                                                                                            335

                                                                                                            201

                                                                                                            345

                                                                                                            479

                                                                                                            268

                                                                                                            412

                                                                                                            SX011868

                                                                                                            340

                                                                                                            420

                                                                                                            38

                                                                                                            –0,04 –0,10

                                                                                                            29

                                                                                                            375

                                                                                                            241

                                                                                                            385

                                                                                                            519

                                                                                                            308

                                                                                                            452

                                                                                                            SX011880

                                                                                                            400

                                                                                                            500

                                                                                                            46

                                                                                                            –0,04 –0,10

                                                                                                            35

                                                                                                            445

                                                                                                            275

                                                                                                            455

                                                                                                            625

                                                                                                            360

                                                                                                            540

                                                                                                            SX0118/500

                                                                                                            500

                                                                                                            620

                                                                                                            56

                                                                                                            –0,04 –0,10

                                                                                                            42

                                                                                                            554

                                                                                                            350

                                                                                                            566

                                                                                                            700

                                                                                                            452

                                                                                                            668

                                                                                                            Clamping rings, bearing seat depth, mounting dimensions

                                                                                                            Fixing screws

                                                                                                            For the location of the bearing rings or clamping rings, screws of grade 10.9 are suitable ➤ Table.

                                                                                                            Any deviations from the recommended size, grade and quantity of screws will considerably reduce the load carrying capacity and operating life of the bearings.

                                                                                                            For screws of grade 12.9, the minimum strength of the clamping rings must be achieved or quenched and tempered seating washers must be used.

                                                                                                            Fixing screws

                                                                                                            Crossed roller bearings

                                                                                                            Fixing screws

                                                                                                            Grade 10.9

                                                                                                            Tightening torque

                                                                                                            Dimension

                                                                                                            Quantity

                                                                                                            MA

                                                                                                            Nm

                                                                                                            SX011814

                                                                                                            M5

                                                                                                            18

                                                                                                            7

                                                                                                            SX011818

                                                                                                            M5

                                                                                                            24

                                                                                                            7

                                                                                                            SX011820

                                                                                                            M5

                                                                                                            24

                                                                                                            7

                                                                                                            SX011824

                                                                                                            M6

                                                                                                            24

                                                                                                            11,7

                                                                                                            SX011828

                                                                                                            M8

                                                                                                            24

                                                                                                            27,8

                                                                                                            SX011832

                                                                                                            M8

                                                                                                            24

                                                                                                            27,8

                                                                                                            SX011836

                                                                                                            M10

                                                                                                            24

                                                                                                            55,6

                                                                                                            SX011840

                                                                                                            M10

                                                                                                            24

                                                                                                            55,6

                                                                                                            SX011848

                                                                                                            M12

                                                                                                            24

                                                                                                            98,4

                                                                                                            SX011860

                                                                                                            M16

                                                                                                            24

                                                                                                            247

                                                                                                            SX011868

                                                                                                            M16

                                                                                                            24

                                                                                                            247

                                                                                                            SX011880

                                                                                                            M20

                                                                                                            24

                                                                                                            481

                                                                                                            SX0118/500

                                                                                                            M24

                                                                                                            24

                                                                                                            831

                                                                                                            Securing of screws

                                                                                                            Normally, the screws are adequately secured by the correct preload ➤ Table and ➤ Table. If regular shock loads or vibrations occur, however, additional securing of the screws may be necessary.

                                                                                                            Not every method of securing screws is suitable for crossed roller bearings. Never use spring washers or split washers.

                                                                                                            General information on securing of screws is given in DIN 25201-4:2004. If these are to be used, please consult the relevant companies.

                                                                                                            Tightening torques MA for the torque-controlled tightening of socket headless screws

                                                                                                            Fixing screw

                                                                                                            Clamping cross‑section

                                                                                                            Core cross‑section

                                                                                                            Tightening torque MA **

                                                                                                            in Nm for grade

                                                                                                            AS

                                                                                                            Ad3

                                                                                                            8.8

                                                                                                            10.9

                                                                                                            12.9

                                                                                                            mm2

                                                                                                            mm2

                                                                                                            M4

                                                                                                            8,78

                                                                                                            7,75

                                                                                                            2,25

                                                                                                            3,31

                                                                                                            3,87

                                                                                                            M5

                                                                                                            14,2

                                                                                                            12,7

                                                                                                            4,61

                                                                                                            6,77

                                                                                                            7,92

                                                                                                            M6

                                                                                                            20,1

                                                                                                            17,9

                                                                                                            7,8

                                                                                                            11,5

                                                                                                            13,4

                                                                                                            M8

                                                                                                            36,6

                                                                                                            32,8

                                                                                                            19,1

                                                                                                            28

                                                                                                            32,8

                                                                                                            M10

                                                                                                            58

                                                                                                            52,3

                                                                                                            38

                                                                                                            55,8

                                                                                                            65,3

                                                                                                            M12

                                                                                                            84,3

                                                                                                            76,2

                                                                                                            66,5

                                                                                                            97,7

                                                                                                            114

                                                                                                            M14

                                                                                                            115

                                                                                                            105

                                                                                                            107

                                                                                                            156

                                                                                                            183

                                                                                                            M16

                                                                                                            157

                                                                                                            144

                                                                                                            168

                                                                                                            246

                                                                                                            288

                                                                                                            M18

                                                                                                            192

                                                                                                            175

                                                                                                            229

                                                                                                            336

                                                                                                            394

                                                                                                            M20

                                                                                                            245

                                                                                                            225

                                                                                                            327

                                                                                                            481

                                                                                                            562

                                                                                                            M22

                                                                                                            303

                                                                                                            282

                                                                                                            450

                                                                                                            661

                                                                                                            773

                                                                                                            M24

                                                                                                            353

                                                                                                            324

                                                                                                            565

                                                                                                            830

                                                                                                            972

                                                                                                            ** MA in accordance with guideline VDI 2230 (February 2003) for μK = 0,08 and μG = 0,12.

                                                                                                            Assembly preload forces FM for the torque-controlled tightening of socket headless screws

                                                                                                            Fixing screw

                                                                                                            Clamping cross‑section

                                                                                                            Core cross‑section

                                                                                                            Mounting preload force FM **

                                                                                                            in kN for grade

                                                                                                            AS

                                                                                                            Ad3

                                                                                                            8.8

                                                                                                            10.9

                                                                                                            12.9

                                                                                                            mm2

                                                                                                            mm2

                                                                                                            M4

                                                                                                            8,78

                                                                                                            7,75

                                                                                                            4,05

                                                                                                            5,95

                                                                                                            6,96

                                                                                                            M5

                                                                                                            14,2

                                                                                                            12,7

                                                                                                            6,63

                                                                                                            9,74

                                                                                                            11,4

                                                                                                            M6

                                                                                                            20,1

                                                                                                            17,9

                                                                                                            9,36

                                                                                                            13,7

                                                                                                            16,1

                                                                                                            M8

                                                                                                            36,6

                                                                                                            32,8

                                                                                                            17,2

                                                                                                            25,2

                                                                                                            29,5

                                                                                                            M10

                                                                                                            58

                                                                                                            52,3

                                                                                                            27,3

                                                                                                            40,2

                                                                                                            47

                                                                                                            M12

                                                                                                            84,3

                                                                                                            76,2

                                                                                                            39,9

                                                                                                            58,5

                                                                                                            68,5

                                                                                                            M14

                                                                                                            115

                                                                                                            105

                                                                                                            54,7

                                                                                                            80,4

                                                                                                            94,1

                                                                                                            M16

                                                                                                            157

                                                                                                            144

                                                                                                            75,3

                                                                                                            111

                                                                                                            129

                                                                                                            M18

                                                                                                            192

                                                                                                            175

                                                                                                            91,6

                                                                                                            134

                                                                                                            157

                                                                                                            M20

                                                                                                            245

                                                                                                            225

                                                                                                            118

                                                                                                            173

                                                                                                            202

                                                                                                            M22

                                                                                                            303

                                                                                                            282

                                                                                                            147

                                                                                                            216

                                                                                                            253

                                                                                                            M24

                                                                                                            353

                                                                                                            324

                                                                                                            169

                                                                                                            249

                                                                                                            291

                                                                                                            ** FM in accordance with guideline VDI 2230 (February 2003) for μG = 0,12.

                                                                                                            Mounting and dismounting

                                                                                                            Mounting of crossed roller bearings

                                                                                                            The bores and edges of the adjacent components must be free from burrs. The support surfaces for the bearing rings must be clean.

                                                                                                            The seating and locating surfaces for the bearing rings on the adjacent construction must be lightly oiled or greased.

                                                                                                            Lightly oil the thread of the fixing screws in order to prevent varying friction factors (do not oil or grease screws that will be secured by means of adhesive).

                                                                                                            Ensure that all adjacent components and lubrication ducts are free from cleaning agents, solvents and washing emulsions. The bearing seat surfaces can rust or the raceway system can become contaminated.

                                                                                                            Mounting forces must only be applied to the bearing ring to be mounted; forces must never be directed through the rolling elements or seals. Avoid direct blows on the bearing rings in all cases.

                                                                                                            Locate the bearing rings consecutively and without application of any external load.

                                                                                                            The outer ring is split and is held together by three retaining rings 

                                                                                                            ➤ Figure. Never apply tensile loads to the retaining rings.

                                                                                                            Locating the outer bearing ring

                                                                                                            Mounting of the ring ➤ Figure:

                                                                                                            • Insert or press the bearing 
                                                                                                              into the external adjacent construction 
                                                                                                              with the outer ring first
                                                                                                              • Position the external clamping ring 
                                                                                                                • Insert the fixing screws 
                                                                                                                  in the clamping ring and tighten in steps up to the specified tightening torque MA
                                                                                                                  • tighten the screws in a crosswise sequence in order to prevent unacceptable fluctuations in the screw tensioning forces
                                                                                                                  • tightening torques MA for fixing screws➤ Table
                                                                                                                  Locating the outer bearing ring
                                                                                                                  Locating the inner bearing ring

                                                                                                                  Mounting of the ring ➤ Figure :

                                                                                                                  • Insert the bearing 
                                                                                                                    into the internal adjacent construction 
                                                                                                                    • Position the internal clamping ring 
                                                                                                                      • Insert the fixing screws 
                                                                                                                        in the clamping ring and tighten in steps up to the specified tightening torque MA
                                                                                                                        • tighten the screws in a crosswise sequence in order to prevent unacceptable fluctuations in the screw tensioning forces.
                                                                                                                        Locating the inner bearing ring

                                                                                                                        Checking the function

                                                                                                                        Once mounting is complete, the operation of the mounted crossed roller bearing must be checked. If the bearing runs irregularly or roughly, or the temperature in the bearing shows an unusual increase, the bearing must be dismounted, checked and mounted again in accordance with the mounting guidelines described.

                                                                                                                        Checking the running accuracy

                                                                                                                        Possible causes of deviations in values

                                                                                                                        The running accuracy must be checked by means of a dial gauge. The corresponding values are taken from the mounting drawing or the product tables. Deviations from the values may be the result of:

                                                                                                                        • inaccuracies in the adjacent construction
                                                                                                                          • braced bearings due to incorrectly tightened clamping rings, fixing screws or locknuts.
                                                                                                                            Checking the rotational resistance

                                                                                                                            Factors influencing the rotational resistance

                                                                                                                            The rotational resistance is essentially determined by:

                                                                                                                            • the rolling resistance of the rolling elements
                                                                                                                              • the internal clearance or bearing preload
                                                                                                                                • the friction of the spacers
                                                                                                                                  • the friction of the seals
                                                                                                                                    • the grease
                                                                                                                                      • a deformed or defective adjacent construction
                                                                                                                                        • errors during mounting.

                                                                                                                                          Preload, rotational resistance, bearing temperature

                                                                                                                                          Due to the preload in the rolling element system, the rotational resistance is higher than in a bearing with clearance. At higher speeds, a high preload can lead to generation of significant heat in the bearing. In such applications, tests must be carried out if necessary with bearings preloaded to various values.

                                                                                                                                          Checking the bearing temperature

                                                                                                                                          Possible causes of high temperatures

                                                                                                                                          After commissioning, the temperature in the bearing can increase; in the case of grease lubrication, this may continue until the grease is evenly distributed in the bearing. A further increase or unusually high temperatures may be caused by one of the following:

                                                                                                                                          • The bearing is lubricated using an unsuitable grease
                                                                                                                                            • There is too much lubricant in the bearing
                                                                                                                                              • The bearing load is too high
                                                                                                                                                • The bearing is mounted unevenly
                                                                                                                                                  • The adjacent construction deviates from the specifications.
                                                                                                                                                    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 without detri­mental effect, they must be handled with care.

                                                                                                                                                    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 of bearings, in the original design of the bearing position. This book is available from Schaeffler on request.

                                                                                                                                                    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:

                                                                                                                                                    • Determining the bearing size
                                                                                                                                                      • Rigidity
                                                                                                                                                        • Friction and increases in temperature
                                                                                                                                                          • Speeds
                                                                                                                                                            • Bearing data
                                                                                                                                                              • Lubrication
                                                                                                                                                                • Sealing
                                                                                                                                                                  • Design of bearing arrangements
                                                                                                                                                                    • Mounting and dismounting.

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