Glossary
Reference speed
Referenzdrehzahl
The reference speed is a thermal rating: the speed at which, under standardized reference conditions for load, lubrication and heat dissipation (ISO 15312), the frictional heat generated in the bearing balances the heat removed via shaft and housing. It is not a mechanical limit but describes thermal equilibrium under standard conditions.
Because real applications deviate from the reference conditions, the permissible operating speed can be higher or lower — better cooling or lighter loads allow higher speeds. The reference speed is mainly a comparison figure between bearing types and sizes; high-speed applications must additionally be checked against the limiting speed and, if needed, a thermal calculation.