(under subclass 545) Apparatus in which the piston is provided with relatively movable valve members which control flow of fluid into and out of the expansible chamber.
SEE OR SEARCH THIS CLASS, SUBCLASS:
260, for successive stage pumps having a valved piston which contains both the inlet and the outlet valve for one of the stages.
486, for a pumping chamber having two or more relatively fixed pumping members and in which the inlet valve is positioned in one working member and the discharge valve is positioned in a second pumping member.
525, for a common valved pumping member for plural pumping chambers in which both the inlet and discharge valves for the chambers are disposed in the pumping member.
