Vacuum control valving apparatus for a vacuum sealed molding apparatus

In a vacuum molding apparatus having a rail conveyor truck with a vacuum source connection thereon and a casting box for producing castings with the aid of binderless sand, said apparatus being comprised of frame-like upper and lower mold members each having an evacuation chamber, the improvement comprising wherein said evacuation chambers have first coupling means for connection to a vacuum source separate from said vacuum source connection on said rail conveyor truck and first normally closed valve means in said first coupling means and connected in circuit therewith for opening and closing said vacuum source connection, said first valve means being opened in response to the application of a vacuum pressure to said first coupling means, said upper and lower mold members each having second coupling means communicating with said evacuation chambers and second valve means for opening and closing said communication to said evacuation chambers, said second valve means being normally closed when said upper and lower mold members are separated from each other, first actuating means for opening said second valve means in response to a placement of said upper mold member in mating relation on top of said lower mold member to establish communication between said evacuation chambers, and third coupling means communicating with said evacuation chamber in said lower mold member and third valve means for opening and closing said communication to said evacuation chamber, said third valve means being normally closed when said lower mold member is separated from said rail conveyor truck, second actuating means for opening said third valve means in response to a placement of said lower mold member in mating relation on top of said rail conveyor truck and connecting said evacuation chamber in said lower mold member to a vacuum source connection on said rail conveyor truck.