System for controlling liquid flow

A system for controlling the flow of liquid between a reservoir and a liquid source, comprising:

• conduit means between said reservoir and said source for the flow of liquid therebetween;
• selectively operable valve means in said conduit means for actuation between a first position for filling the reservoir with liquid from said source and a second position for emptying liquid from the reservoir to said source;
• automatic check valve means in said conduit means for preventing the flow of liquid from the reservoir to said source when said selectively operable valve means is in said first, filling position and for preventing the flow of liquid from said source to the reservoir when said selectively operable valve means is in said second, emptying position;
• said conduit means comprising a passageway through a housing, and said selectively operable valve means and said automatic check valve means comprising a unitary structure in said housing for controlling both the flow of liquid through the housing in either direction and for checking the flow of liquid in the respective opposite direction;
• and
• said housing having an inlet thereto from said source and an outlet therefrom to the reservoir, a first check valve member operatively associated with said inlet to permit the flow of liquid through the housing only from said source when said selectively operable valve means is in said first position, and a second check valve member operatively associated with said outlet to permit the flow of liquid through the housing only from said reservoir when said selectively operable valve means is in said second position.