Studer RHU-450 and RHU-500 Semi-universal Cylindrical Grinder Manual Studer RHU-450 Semi-Universal Cylindrical Grinder: Two editions of the Operating and Maintenance Manual with a Parts Manual as Sectional Drawings and Electrical Schematics. 315 detailed pages. Manufacturers: Studer Models: 450 500 RHU Contents: Operators Manual Maintenance Manual Electrical Diagrams