Selection of bearing arrangement

As bearing operational conditions vary depending on devices in which bearings are mounted, different performances are demanded of bearings. Normally, two or more bearings are used on one shaft.

In many cases, in order to locate shaft positions in the axial direction, one bearing is mounted on the fixed side first, then the other bearing is mounted on the free side.

Table 4-1 Bearings on fixed and free sides

FeaturesRecommended bearing typeExample No.
Fixed side bearing
  • This bearing determines shaft axial position.
  • This bearing can accommodate both radial and axial loads.
  • Since axial load in both directions is imposed on this bearing, strength must be considered in selecting the bearing for this side.
Deep groove ball bearing
Matched pair or stack angular contact ball bearing
Double-row angular contact ball bearing
Self-aligning ball bearing
Cylindrical roller bearing with rib
(NUP and NH types)
Double-row tapered roller bearing
Spherical roller bearing
Examples
1−11
Free side bearing
  • This bearing is employed to compensate for expansion or shrinkage caused by operating temperature change and to allow ajustment of bearing position.
  • Bearings which accommodate radial load only and whose inner and outer rings are separable are recommended as free side bearings.
  • In general, if non-separable bearings are used on free side, clearance fit is provided between outer ring and housing to compensate for shaft movement through bearings.
    In some cases, clearance fit between shaft and inner ring is utilized.
  • Separable types
    Cylindrical roller bearing
    (NU and N types)
    Needle roller bearing
    (NA type, etc.)
  • Non-separable types
    Deep groove ball bearing
    Matched pair angular contact ball bearing
    (Back-to-back arrangement)
    Double-row angular contact ball bearing
    Self-aligning ball bearing
    Double-row tapered roller bearing
    (TDO type)
    Spherical roller bearing
When fixed and free sides are not distinguished
  • When bearing intervals are short and shaft shrinkage does not greatly affect bearing operation, a pair of angular contact ball bearings or tapered roller bearings is used in paired mounting to accommodate axial load.
  • After mounting, the axial clearance is adjusted using nuts or shims.
Deep groove ball bearing
Angular contact ball bearing
Self-aligning ball bearing
Cylindrical roller bearing
(NJ and NF types)
Tapered roller bearing
Spherical roller bearing
Examples
12−16
Bearings for vertical shafts
  • *Bearings which can accommodate both radial and axial loads should be used on fixed side.
    Heavy axial load can be accommodated using thrust bearings together with radial bearings.
  • Bearings which can accommodate radial load only are used on free side, compensating for shaft movement.
  • Fixed side
    Matched pair angular contact ball bearing
    (Back-to-back arrangement)
    Double-row tapered roller bearing
    (TDO type)
    Thrust bearing + radial bearing
Examples
17 and 18

Table 4-2 Example bearing arrangements

ExampleBearing arrangementRecommended applicationApplication example
Fixed sideFree side
Ex. 1
a_21_001.png
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  • Suitable for high-speed operation; used for various types of applications.
  • Not recommended for applications that have center displacement between bearings or shaft deflection.
Medium size motors,
air blowers
Ex. 2
a_21_003.png
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  • More suitable than Ex. 1 for operation under heavy load or impact load. Suitable also for high-speed operation.
  • Due to separability, suitable for applications requiring interference of both inner and outer rings.
  • Not recommended for applications that have center displacement between bearings or shaft deflection.
Traction motors for railway rolling stock
Ex. 3
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  • Recommended for applications under heavier or greater impact load than those in Ex. 2.
  • This arrangement requires high rigidity from fixed side bearings mounted back to back, with preload provided.
  • Shaft and housing of accurate dimensions should be selected and mounted properly.
Steel manufacturing table rollers,
lathe spindles
Ex. 4
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a_21_008.png
  • This is recommended for operation at high speed or axial load lighter than in Ex. 3.
  • This is recommended for applications requiring interference of both inner and outer rings.
  • Some applications use double-row angular contact ball bearings on fixed side instead of matched pair angular contact ball bearings.
Motors
Ex. 5
a_21_009.png
a_21_010.png
  • This is recommended for operations under relatively small axial load.
  • This is recommended for applications requiring interference of both inner and outer rings.
Paper manufacturing calender rollers,
diesel locomotive axle journals
Ex. 6
a_21_011.png
a_21_012.png
  • This is recommended for operations at high speed and heavy radial load, as well as normal axial load.
  • When deep groove ball bearings are used, clearance must be provided between outside diameter and housing, to prevent application of radial load.
Diesel locomotive transmissions
Ex. 7
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  • )This arrangement is most widely employed.
  • This arrangement can accommodate partial axial load as well as radial load.
Pumps,
automobile transmissions
Ex. 8
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  • This is recommended for operations with relatively heavy axial load in both directions.
  • )Some applications use matched pair angular contact ball bearings on fixed side instead of doublerow angular contact ball bearings.
Worm gear
speed reducers
Ex. 9
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  • This is the optimum arrangement for applications with possible mounting errors or shaft deflection.
  • Bearings in this arrangement can accommodate partial axial load, as well as heavy radial load.
Steel manufacturing table roller speed reducers,
overhead crane wheels
Ex. 10
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  • This is optimum arrangement for applications with possible mounting errors or shaft deflection.
  • Ease of mounting and dismounting, ensured by use of adaptor, makes this arrangement suitable for long shafts which are neither stepped nor threaded.
  • This arrangement is not recommended for applications requiring axial load capability.
General industrial equipment counter shafts
Ex. 11
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a_22_008.png
  • This is the optimum arrangement for applications with possible mounting errors or shaft deflection.
  • )This is recommended for operations under impact load or radial load heavier than that in Ex. 10.
  • This arrangement can accommodate partial axial load as well as radial load.
Steel manufacturing table rollers
ExampleArrangement in which fixed and free sides are not distinguishedRecommended applicationApplication example
Ex. 12
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  • This arrangement is most popular when applied to small equipment operating under light load.
  • When used with light preloading, thicknessadjusted shim or spring is mounted on one side of outer ring.
Small motors,
small speed reducers,
small pumps
Ex. 13
a_22_010.png

Back-to-back

a_22_011.png

Face-to-face

  • This is suitable for applications in which rigidity is enhanced by preloading.
    This is frequently employed in applications requiring high speed operation under relatively large axial load.
  • Back-to-back arrangement is suitable for applications in which moment load affects operation.
  • When preloading is required, care should be taken in preload adjustment.
Machine tool spindles
Ex. 14
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Back-to-back

a_23_002.png

Face-to-face

  • This is recommended for operation under impact load or axial load heavier than in Ex. 13.
  • This is suitable for applications in which rigidity is enhanced by preloading.
  • Back-to-back arrangement is suitable for applications in which moment load affects operation.
  • When interference is required between inner ring and shaft, face-to-face arrangement simplifies mounting. This arrangement is effective for applications in which mounting error is possible.
  • When preloading is required, care should be taken in preload adjustment.
Speed reducers,
automobile wheels
Ex. 15
a_23_003.png
  • This is recommended for applications requiring high speed and high accuracy of rotation under light load.
  • This is suitable for applications in which rigidity is enhanced by preloading.
  • Tandem arrangement and face-to-face arrangement are possible, as is back-to-back arrangement.
Machine tool spindles
Ex. 16
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  • This arrangement provides resistance against heavy radial and impact loads.
  • This is applicable when both inner and outer rings require interference.
  • Care should be taken not to reduce axial internal clearance a critical amount during operation.
Construction equipment final drive
ExampleApplication to vertical shaftsRecommended applicationApplication example
Ex. 17
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  • This arrangement, using matched pair angular contact ball bearings on the fixed side and cylindrical roller bearings on the free side, is suitable for high speed operation.
Vertical motors,
vertical pumps
Ex. 18
a_23_006.png
  • This is recommended for operation at low speed and heavy load, in which axial load is heavier than radial load.
  • Due to self-aligning capability, this is suitable for applications in which shaft runout or deflection occurs.
Crane center shafts,
vertical pumps
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