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Machine elements

Rolling-bearing selection and load direction

Bearing selection begins with the complete load case—not the shaft diameter alone. Radial and axial forces, speed, misalignment, stiffness, thermal growth, available space, lubrication and contamination determine the bearing type and arrangement.

LOAD DIRECTION

Match the internal geometry to the force

  • Deep-groove ball bearing: versatile radial support with moderate axial capability.
  • Angular-contact or tapered roller bearing: combined radial–axial loading; commonly arranged in opposed pairs.
  • Cylindrical roller bearing: high radial capacity and stiffness; flange arrangement determines axial guidance.
  • Self-aligning bearing: accommodates angular misalignment that would overload a rigid bearing arrangement.
SYSTEM ARRANGEMENT

Locate once and allow thermal movement

A locating bearing controls the shaft axially. The non-locating bearing must permit thermal expansion through internal displacement or a deliberate sliding fit.

Load path · axial location · thermal growth · sealing · lubrication

Constraining both ends without an expansion path can create unintended preload, heat and early failure—even when each bearing is individually large enough.

Design conditionSelection response
High radial loadCompare cylindrical or needle rollers; verify speed, shaft hardness and installation space.
High or reversing axial loadUse a defined thrust-capable arrangement and check directionality, pairing and preload.
Misalignment or housing deflectionUse self-aligning capability or correct the structural cause; rigid bearings are sensitive to edge loading.
Water and stone dustTreat sealing, housing drainage, grease renewal and shaft-surface condition as part of bearing selection.
SourcesSource basis: Ulrich Fischer et al., Mechanical and Metal Trades Handbook, rolling-bearing overview, designation and selected ball/roller bearings, pp. 263–267.
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