Interested to see a video if you ever get the chance. I think you've approached this differently than my pounder's operation. Mine uses hydraulics to raise the ram against force of a huge spring. Then return hydraulics from cylinder gets dumped directly into tank to allow spring contraction and gravity to pull down the ram head. This requires large return line plumbed directly into tank, can't be any resistance or it diminshes downward force of ram, PITA. Yours looks like hydraulics power both the downstroke and upstroke, seems like much better approach. But you still must have to get that return flow discharged really quickly, or you'll limit the speed of downward motion. Or do you have some kind of secondary reservoir that captures the discharge?