To reduce the required manual effort applied or to minimize the pressure shocks a manual gearbox is preffered. A gearbox allows greater ease of operation and gives a better protection against system damage caused by waterhammer due to quick closing. For regulating valves with a gearbox the system can be properly balanced by fine manual control. Casing materials are cast aluminium, cast iron, ductile iron or stainless steel. The available operating devices for gearbox are handwheels, tee caps for buried service or chainwheels for overhead installations.