The adjustable valves can operate from a 3:1 to 21:1 hydraulic-to-air-pressure ratio, at temperatures to 250°F. Mico Inc., 1911 Lee Blvd., North Mankato, MN 56003, (507) 625-6426, www.mico.com ...

The combination of hydraulic relay valves and servos with the flyweight governors ended up being the perfect contraption needed for hydro-electric turbines. These devices became known as ...