Here's the deal guys......Normaly when you raise your 3ph all the way up (lever full up) when the hitch reaches it's highest position the feed back linkage moves the control valve back to the neutral position. If the feed back linkage is out of adjustment, damaged or missing this operation will not take place and the hitch will hit the stop usually internally and the valve will remain in the raise position causing the relief valve to open. This will cause your hyd oil to over heat, it will also cause damage to the hyd. pump if allowed to run this way for a long period of time. Depending on the model and make of your tractor and this goes for most makes of tractors not just Kubota, it will cause your loader to function very erratically due to the fact that power beyond from the loader goes to the 3ph next in most cases. It will also rob power from the engine due to the hyd pump trying to squeeze all that fluid past the small orifice in the relief valve. As long as the feedback linkage is functioning properly you can run with the lever all the way up with no problem. Now, how do you know the feed back is functioning you ask? Easy, at idle, raise the hitch all the way up and watch your engine rpm (or listen to the engine, for the tach impaired) you should see/hear an initial drop off of rpm especially if you have a heavy impliment installed. When the hitch raises fully rpm should then increase to what it was initially. This indicates that the valve has gone back to neutral and the hydraulic system is not running over relief. Also keep in mind that once the hitch raises up and stops/kicks back to neutral you should have a small amount of play at the top (should be able to lift the arms up just a little more). Anyway, if you don't need the lever all the way up then follow the tip in case the linkage malfunctions and you don't notice. If your having engine power issues, loader or other hyd powered impliment issues then drop the lever to see if that clears things up.
