How exactly does 8n make hydraulic pressure?

[BarnCat]

My 3 point has needed work for a while. I knew a piston and lift cylinder were needed, and one chamber kit came in a parts lot I bought, so I decided to get one more chamber kit and the safety valve and just do all that while it was tore apart. The chamber kits appear to be of varying quality. So my question is, how do these make pressure? Is the outer diameter more important, or the taper? Also, the old springs from the tractor are stiffer and springier than either of the new kits. Should the springs be softer or more firm? Some of my worn parts have a larger outer diameter than the new ones, but the new ones have much nicer tapers. One of my new kits, the very smallest piece that goes on the end of the rod, in the bottom of the chamber wasn’t drilled concentric with the OD, so it probably isn’t any good. Pics attached of the used parts, kits, and their respective O.D. The first pic is the kit that came in a parts lot, the second is the new one I bought a while ago that isn’t drilled correctly, and the third are the used parts out of the tractor.

 

[JMOR]

Maybe this will help.

https://imgur.com/VHFoPFA

As piston retracts, inlet valve is sucked open and fluid flows in, then as piston moves in other direction, fluid trying to leave cylinder pushes inlet valve closed and outlet valve open. Neither has much to do with pressure. Pressure is built by whatever restricts flow out, such as in a lift cylinder lifting nothing results in little pressure, whereas trying to lift 1,000 pounds results in hundreds or 1, 000+ pounds of pressure.