Detailed technical content
Choose the design according to the raceway surface and installation space
Needle roller bearings are available in many configurations. A needle-and-cage assembly has no separate inner or outer ring, giving the smallest cross-section but requiring the shaft and housing to have suitably machined raceway surfaces. A drawn-cup bearing uses a thin drawn-steel outer ring and is suitable where a compact design is required and the housing bore can be used directly for press-fitting. A machined-ring bearing has a more rigid outer ring and is suitable for more demanding load and precision-mounting requirements.
Some self-aligning designs use a special outside surface or support ring to compensate for static misalignment between the shaft and housing. This capability is limited and is not intended to handle continuous dynamic misalignment.
The shaft surface may form part of the bearing
In a design without an inner ring, the shaft itself forms the raceway. Shaft hardness, roughness, roundness and tolerances therefore directly affect clearance and service life. If the shaft cannot be machined to the required specification, choose a configuration with a separate inner ring.
When selecting a designation, identify the radial space, whether an inner ring is present, housing style, load, speed, mounting surface and sealing requirements.
