Ball tube mill vibration

[Tmoose]

Ball tube mills are used to grind up coal, limestone, cement and probably lots of other things too. The bigger ones (maybe 8 foot diameter and larger, 10 or more feet long ) have a journal bearing over 4 feet in diameter on each end. They turn pretty slow. way Under 100 rpm.

Has anyone seen any specifications for bearing housing vibration that might reasonably apply to these things?

thanks

Dan T