hydraulic manifold ?

[fxrs55]

Using the tank port as a supply for another circuit is a common mistake and usually results in the failure you describe of a crack in the valve body. Further, you eliminate a relief valve working properly as it needs a path to the tank to save you from destroying the pump. There is lots of junk hydraulic advice on the web.

This out port pressure restriction is common as you have found.

Years ago companies like Kubota made hydraulic blocks that could be added by their customers in order to acquire more circuits.

The big difference between the 3 pt hitch and the circuits you want to add is the 3 pt uses a single acting hydraulic cylinder, whereas, because you want to control double acting cylinders you need a control valve and not try to use the 3 pt control valve

Dave M7040

For what its worth, I was only showing what was put on my tractor
by a Bolens dealer to add the front snow blade. My setup does not use the 3 point control valve to operate the front blade. The illustration you show for the kubota hydraulic block is exactly how my manifold works to add another circuit. This feeds a set of valves to operate the front blade. This setup has been on my tractor since 1978
when this tractor was bought new by the first owner.
Here is a picture of the valves to operate the blade.
Also the 3 point and the front blade operate independent of each other
they only share the same high pressure feed.
I'm not interested in posting just to run up my post count to be in high
post club. I don't pretend to be a know it all. I wouldn't want to
see anyone getting hurt from using a make shift asinine rig job.