High Precision Ball Bearings - Kraftmek

Types of preload
Spring preload
Characteristics:
• Insensitive to different thermal expansion of shaft and
housing
• Suitable for very high speeds
The drawing shows a spindle where bearing 1 has a
fixed location, whereas the outer ring of bearing 2 is free
to move axially. The spring force acts on the outer ring
of bearing 2 and results in a permanent preload of both
bearings almost independent of speed and temperature
factors. Care must be taken to ensure easy movement
of the adjusted outer ring. Bearings preloaded in this
way can be used up to the limiting speed of single
bearings if oil lubrication is used. The spring has to be
arranged to be effective in the same direction as the
external axial load.
Rigid preload
Characteristics:
• Higher rigidity at radial loads
• Lower limiting speed compared to spring preload
• The magnitude of preload changes due to length
variations as a result of temperature differences
between shaft and housing
• Distinct higher axial rigidity than with spring preload
With the spindle shown in the drawing both bearings
are paired and mounted stationary in an axial direction.
Bearings arranged like this have a defined axial preload.
The sleeves shown in the diagram must be ground to
the identical length in one setting. GMN deliver the
required bearing pairs with the necessary preload. The
change of the preload under operating conditions has
to be considered.
Bearing 1 Bearing 2
Bearing 1 Bearing 2
... for design of the bearing application
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