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Select Selection ion of bearing design
Selection of the bearing design
Starting with the ball bearings, which represented the start of the technical development of roller bearings, today,
there is a large number of bearing types and designs that can be employed by preference for specific load conditions.
Therefore, any design of a roller bearing will be a technical compromise that is determined by the most varied
different criteria:
Roller bearings are selected according to:
• the available space conditions
• type and magnitude of the load
• speeds or movement cycles in general
• the necessary guidance accuracy of the machine or plant components
• the bearing stiffness
• the environmental conditions
• the possibilities for assembly and dismantling
Apart from the technical parameters of a roller bearing, such as the load capacity and permissible speeds, the bearing
clearance or pretension, the tailored cage modification and the lubrication method must also be taken into
consideration when selecting the bearing design. In the roller bearings on offer from KRW, there are generally no
seals integrated, due to their geometry and quantity, so the problem of sealing in the context of the lubricant has
to be resolved by the user.
Deep groove ball bearings
According to general information, this design type is used most frequently; this does not apply particularly to the
diameter range exceeding 600 mm.
If both radial as well as axial forces have to be absorbed in combination with changing operating conditions, the
advantages of high permissible speeds and high reliability can be exploited. Since this bearing design cannot be dismantled
and only allows a small tilting angle (about 10‘), there are limits to its usability, especially in heavy machinery
manufacturing.
Angular contact ball bearings
Depending on the size of the dimension series and the implemented contact angle, angular contact ball bearings
may have a high axial load capacity. High stiffness and good guiding accuracy are achieved especially in the pretensioned
state. Single row angular contact ball bearings are usually mounted in pairs. KRW also manufactures 2-row
angular contact ball bearings for special applications, e.g. in hydraulic pumps (bearing design SKZ).
Four point bearings
Four point bearings are a special form of the angular contact ball bearing. They accept axial loads in both directions.
KRW can supply four point bearings both with the split inner ring (bearing design QJ) as well as with a split outer
ring (bearing design Q). The split design of the bearing rings provides a particular degree of ease of assembly, e.g.
in gearbox manufacturing.
Cylindrical roller bearings
This bearing design has, in the most varied design versions, a very large number of variation possibilities, without
the high radial loading capacity having to be restricted. In general, the following applies: a cylindrical roller bearing
has a load capacity of up to 60 % higher than the comparable deep groove ball bearing. Individual design versions
of the cylindrical roller bearing can also absorb single-sided axial forces.
Cylindrical roller bearings are manufactured in single row, multi-row, with and without cages, they can be dismantled
and hence, are easy to assemble at the customer site.
Two-row cylindrical roller bearings, with cylindrical or conical bores are available with the highest precision, e.g. supporting
work spindles in machine tools. Multi-row cylindrical roller bearings, paired and, in the special design, with
a hot steel riveted pin cage are used in rolling mills. The range of KRW includes cageless cylindrical roller bearings
with the highest loading capacity
Tapered roller bearing
Tapered roller bearings can be dismantled and are used mostly in pairs for high axial load types. Paired bearings are
also suitable for absorbing high radial forces. Tapered roller bearings generally have higher bearing capacities than
comparable angular contact ball bearings, but the magnitude of the speed is limited.
High demands are put on the precision of the modifying parts, since the permissible tilting angle is just
about 2 - 4‘.
KRW 81