In Reply to: 8-N hydro question posted by Bigtom1960 on August 06, 2017 at 12:39:59:
The plug is a tee into the lift cylinder circuit and was intended to be a test port for checking hydraulic pressure. The only time there is pressure present is when the 3pt control lever is in the UP position and there is a load on the 3pt arms. The pressure is what is required to lift the load on the 3pt.
The port can be used as a crude pressure outlet by chaining or otherwise restraining the lift arms in the down position. In that situation moving the 3pt control lever to the top activates the pump and creates full pump pressure at the test port. The chains/restraints also prevent the lift arms from coming to the top which would shut off the hydraulic pump.