NBC Adaptive Sleeves

Adapter sleeves are accessory components used when mounting bearings with a tapered inner bore onto a cylindrical shaft (or sometimes on a stepped shaft). They allow the bearing to be easily mounted, positioned, and locked in place on the shaft. 
From NBC’s own leaflet:

“They can be used on plain and stepped both types of shaft. … When an adapter sleeve is used, the bearing can be positioned anywhere on the plain shaft. It requires no additional support for retention on the shaft and is easy to mount and dismount.” 

They also make “withdrawal sleeves” (for easy dismounting) under the same product family. 

⚙️ How they work: key features & benefits

• The adapter sleeve has a tapered outer surface (commonly 1:12 or 1:30 taper) that mates with the tapered bore of the bearing. The sleeve is fitted on the shaft; the bearing slides over the sleeve; then a lock-nut or locking device secures everything.

• Advantages: Easier mounting/dismounting, shaft protection, allows use of cylindrical shaft even for tapered-bore bearings. 

• NBC’s specification says these sleeves cover shaft sizes from ~25 mm to ~500 mm