These were fairly simple systems consisting of an infra-red sensor with a horizontally rotating shutter in front of it.
Fixed-altitude mounts usually have the primary optics fixed at an altitude angle while rotating horizontally (in azimuth).
With the push of a button both doors open up and rotate horizontally to form wings, then the grill opens up to reveal a propeller.
Mower Blade - a rotary mower generally has one blade that rotates horizontally.
Second, the cars are free to rotate horizontally or "roll" while the ride is in motion, always keeping the riders right-side-up.
A swivel is a connection that allows the connected object, such as a gun or chair, to rotate horizontally and/or vertically.
The 301-foot span rotates horizontally, around a central pivot, so ships can pass.
This mobile sculpture has concentric circles that exist in several planes, but the entire sculpture only rotates horizontally and vertically.
In 1996 Berger modified his original design with the Austrian flag rotated horizontally.