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An Adjustable Toggle Valve is designed to maintain a constant pressure on its output, by fully opening when needed, and fully closed when not needed—not in the middle.
In the figure, the valve is on a swinging connecter. Both the adjustment, and a pressure sensitive diaphragm are connected to another swinging connecter. When the output pressure is such that the Valve is to be closed, in position “A”, the Spring pushes it closed tight.
As pressure releases, the diaphragm pushes on the Spring. Only when the spring-loaded swiveling connector reaches a point past the balance point on the other swinging connecter will that connector suddenly swing to position “B” and open the valve.
This is not the only pressure maintaining valve, but it is the only one that switches suddenly from open to closed, and back.
There are other “Toggle Valves” too, but they are operated by hand rather than pressure.
Thanks for your interest.
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