Viscotherm AG

Viscotherm AG is a family-owned Swiss company headquartered in Hinteregg near Zurich, with over 50 years of specialization in hydrostatic drive systems for decanter centrifuges and dynamic test benches. The company's core product is the ROTODIFF, a hydraulic radial roller piston motor that serves as the scroll drive in decanter centrifuges, replacing conventional gearboxes with a significantly superior weight-to-torque ratio. The standard ROTODIFF range spans from 816 Nm to over 79,000 Nm of torque at bowl speeds up to 6,500 rpm, with a maximum working pressure of 250 bar. Specific models include the compact 1060 S017 (816 Nm, 6,500 rpm, 27 kg), the mid-range 1071 S (4,460 Nm, 4,500 rpm, 70 kg), the 1080 D (16,616 Nm, 3,500 rpm, 170 kg), and the large-capacity 1120 Q-GVL (79,259 Nm, 3,000 rpm, 550 kg). The KOAX-ROTODIFF variant provides coaxial hydraulic connections for simplified piping. The ROTODIFF AVN variant serves dynamic test bench applications for gear units and couplings. Key advantages over conventional gear drives include roughly double the specific torque per kilogram, overload protection via safety pressure valve, automatic heat dissipation through oil conditioning, and proportional torque-to-pressure enabling precise closed-loop control. ATEX-certified versions are available for explosion-hazardous environments. Viscotherm supplies drive system configurations in both semi-hydraulic (scroll only) and fully hydraulic (scroll plus bowl) arrangements, along with matching pump units and electronic control units.