Each bearing type displays characteristic
properties, based on its design, which makes it
more or less appropriate for a given application.
For example, deep groove ball bearings can
accommodate moderate radial loads as well as
axial loads. They have low friction and can be
produced with high precision and in quiet running
variants. Therefore they are preferred for small
and medium-sized electric motors.
Spherical and toroidal roller bearings can carry
very heavy loads and are self-aligning. These
properties make them popular for example, in
heavy engineering applications, where there are
heavy loads, shaft deflections and misalignments.
In many cases, however, several factors have to be
considered and weighed against each other when
selecting a bearing type, so that no general rules
can be given.
The information provided here should serve to
indicate which are the most important factors to
be considered when selecting a standard bearing
type and thus facilitate an appropriate choice:
• Available space
• Loads
• Misalignment
• Precision
• Speed
• Quiet running
• Stiffness
• Axial displacement
• Mounting and dismounting
• Integral seals
An overview of the standard bearing types, their
design characteristics and their suitability for the
demands placed on a given application will be
found in the matrix on pages 12 and 13. Detailed
information on the individual bearing types,
including their characteristics and the available
designs, will be found in the sections dealing with
individual bearing types. Bearing types that are not
included in the matrix are generally only used for a
few well-defined applications.
The matrix permits only a relatively superficial
classification of bearing types. The limited number
of symbols does not allow an exact differentiation
and some properties do not depend solely on
bearing design. For example, the stiffness of an
arrangement incorporating angular contact ball
bearings or taper roller bearings also depends
on the applied preload and the operating speed,
which is influenced by the precision of the bearing
and its associated components as well as by the
cage design. In spite of its limi tations, the matrix
on pages 12 and 13 should enable an appropriate
comparison of bearing types. It should also
be considered that the total cost of a bearing
arrangement and inventory considerations could
also influence the final choice.
Other important criteria to be observed when
designing a bearing arrangement – load carrying
capacity and life, friction, permissible speeds,
bearing internal clearance or preload, lubrication,
sealing etc. – are dealt with in the SKF Rolling
bearings catalog (17000 EN).
Available space
In many cases, one of the principal dimensions of a
bearing – the bore diameter – is predetermined by
the machine’s design and the shaft diameter.
For small-diameter shafts all types of ball bearings
can be used, the most popular being deep groove
ball bearings; needle roller bearings are also
suitable (Figure 1a). For large-diameter shafts,
cylindrical, taper, spherical and toroidal roller
bearings are available, as well as deep groove ball
bearings (Figure 1b).
When radial space is limited, bearings with a small
cross section, particularly those with a low crosssectional height, should be chosen, i.e. bearings in
the 8 or 9 diameter series.
For purely axial loads, needle roller and cage thrust
assemblies (with or without washers) as well as
thrust ball bearings and cylindrical roller.
