This assembly may in turn form part of another servomechanism. Speed control via a governor is another type of servomechanism. Some simple electronics provide a closed-loop servomechanism. The cataract, like most regulators, is an example of a servomechanism. The servomechanism was hydraulic, and propulsion electric. The Ragonnet power reverse, patented in 1909, was a true feedback controlled servomechanism. During World War II he was particularly involved with servomechanism problems. By contrast a car's cruise control uses closed-loop feedback, which classifies it as a servomechanism. Many autofocus cameras also use a servomechanism to accurately move the lens.