In this film, you can imagine that on the other side of the valves there is the same disc as at the top and of course the wedges when it is to be closed, does the same at the bottom as this disc at the top of the springs
https://youtu.be/uUYn5kFFb5s
https://youtu.be/WtqDHJDN79w
https://youtu.be/_REQ1PUM0rY
https://youtu.be/pFTQrxQ3C3E
Andrew
