Free space on both sides of the bearing

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Design of bearing arrangements

Free space on both sides of the bearing
To enable axial displacement of the shaft relative to the housing, free space must be provided on both sides of the bearing as indicated in fig. 1. The value for the width of this free space is based on:
  • the value Ca (→ product tables)
  • the expected axial displacement of the bearing rings from the central position during operation
  • the displacement of the rings caused by misalignment

For additional information, refer to Axial displacement.

Calculating the free space required on both sides of the bearing

Careq = Ca + 0,5 (s + β k1 B)


=bearing width [mm]
Ca=minimum width of space required on both sides of the bearing [mm] (→ product tables)
Careq=width of space required on both sides of the bearing [mm]
k1=misalignment factor (→ product tables)
s=relative axial displacement of rings, e.g. thermal shaft expansion [mm]
β=misaligment [°]
Offset mounting
If considerable thermal changes in shaft length can be expected, the inner ring can be mounted offset, relative to the outer ring, up to the axial displacement limit s1 or s2 (fig. 2) in the direction opposite to the expected shaft expansion (fig. 3) or contraction. Offsetting one ring relative to the other, extends the permissible axial displacement. This advantage is used, for example, in the bearing arrangements of drying cylinders in paper machines.
Bearings on sleeves
CARB bearings with a tapered bore can be mounted with:
  • an adapter sleeve on plain or stepped shafts (fig. 4 or fig. 5)
  • a withdrawal sleeve on stepped shafts (fig. 6)

CARB bearings on an adapter sleeve:

  • Adapter sleeves are supplied complete with a locking device.
  • Use appropriate SKF adapter sleeve assemblies to prevent the locking device from interfering with the cage (→ product table).
  • Check axial displacement carefully, as it could be that s1 (→ product tables) cannot be fully realized.

For additional information about sleeves, refer to Bearing accessories.

Appropriate bearing housings

SKF standard housings are available for almost all CARB bearings in the C 30, C 31, C 22 and C 23 series.

Two arrangements are possible when using standard housings, without requiring special considerations:

  • CARB bearings with a tapered bore on an adapter sleeve and a plain shaft
  • CARB bearings with a cylindrical bore on a stepped shaft

The comprehensive assortment of SKF bearing housings is provided in the following tables:

  • Split plummer (pillow) block housings (table 1)
  • Non-split housings (table 2)
  • Application-specific housings (table 3)
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