Needle roller bearings

Solid needle bearings are single or dual-row bearings and consist of machined outer rings with borders, needle bearings and (depending on model) removable inner rings.
If particularly-space-saving bearings are required, needle bearings without inner rings can be constructed as long as the shaft raceway is hardened and polished. If the shaft has not been designed as a raceway, then bearings with inner rings have to be constructed.
Since lubrication is necessary, most solid needle bearings are fitted with a circumferential groove with lubrication bore.

Adjustable needle bearings consist of a non-machined outer bush, supporting rings in plastic, outer rings with a spherical shell surface, needle roller cage assemblies and (depending on model) removable inner rings.
Adjustable needle bearings are used if static alignment errors on the shaft with respect to the housing have to be compensated for. Alignment errors of up to 3° can be compensated using this bearing type. These bearings may not be used to withstand swivelling and tumbling movements!
If the shaft has been designed as a raceway, bearings without inner rings can be used. Otherwise, bearings with inner rings are required.