Where does the pressure on the top of the back cylinder go when the top valve is closed when the ram is up and just idling? Specifically on the one that you built
The top valve is never closed. The port to the rear cylinder is always open, and the other two ports are divided evenly between open and closed. At idle, ram up, in the top valve, the port to the front cylinder is closed and the top port (exhaust) is open, so the air from the rear cylinder is just breathing in and out of that port.
@@user-xo5vw9gk3x there are a couple of valves called balance valves built in to the cylinder that open briefly to atmosphere at the top and bottom of each stroke. It’s covered pretty well in my 2000 book about how the Nazel works and how I built my first hammer, and how to do it will be covered very specifically in the diy plans.