Great Dane excavating co.

[Old Guy]

Cooper

Used to work in a machine shop building 3 stage dump cylinders, what we built had the oil enter the bottom of the cylinder. The bottom looked just like yours except it had a port, no port at top. we then welded a heavier flange on the bottom of the second and third stage in which we machined the seal groove. For the top of first stage we did same as you, we did internal thread for the other 2, know you can't do this so just repeat what you did on #1 stage, no seals just make sure that the inside of caps are smooth. Double O rings on bottom are fine gives a better seal. My model 300 ton has this type of cylinder works great, and 1/16" size difference is fine even for tops work fine as seals are inside of piston, and no seal at top allows air to flow out through heads.

Earl