The assignee of the present application is the owner of several U.S. patents relating to prior control devices comprising electrical switches combined with vacuum selector valves, but in such prior devices, the movable operating members for the electrical switches and vacuum control valves have linear movement or lever action, and not rotary movement. Such prior patents include Raab and Cobb U.S. Pat. No. 3,942,555; Raab and Halstead U.S. Pat. No. 4,054,761; Raab U.S. Pat. No. 4,126,153; Raab and Halstead U.S. Pat. No. 4,251,698; Raab and Halstead U.S. Pat. No. 4,291,725; and Halstead and Black U.S. Pat. No. 4,448,390.
The problem has been presented of developing rotary action vacuum-electric control devices, combining electrical switches with vacuum control valves.
USPTO Backgrounds
USPTO Backgrounds