Ford 7710 having a hard time to pull itself

(quoted from post at 21:55:13 10/14/15) What do you mean when you say that it can hardly pull itself in higher gears? is the engine lugging down or getting the staggers or does it simply seem that the clutch is slipping.. ie the tractor slows down while the engine maintains speed? Without knowing that we're just flailing in the dark...

Rod

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(quoted from post at 05:44:51 10/15/15)

We adjusted the clutch! N it never changed anything. We pliers 10 acres with it in 3rd gear n it had no problem!

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(quoted from post at 08:15:02 10/15/15) Kinda what I thought.... the cues here were DP hasn't worked in 3k hours and clutch was replaced 300 hours ago... You most likely have a dual power problem.
What you need to do FIRST AND FOREMOST is test the PTO/dual power system pressure. If you crawl under her on the right side and look at the hydraulic pump you will see a line running down/forwards at an angle from the bottom of the main pump. This is the pressure supply line to the DP and MFWD clutch. If the tractor has MFWD there will be a second line from this adapter. If you again look at the pump you will see a riser in the pump body where this adapter attaches that also runs at an angle towards the oil filter. Depending on the age of the tractor or if it has an updated pump it may have a 1/8" NPT plug with an allen head on it in that manifold (riser). If it has that you're in luck. What you need is a hydraulic pressure gauge that reads somewhere in the range up to 300-500 psi depending on what you can lay your hands on. Adapt it to that port in the riser or if you can't do that you will need to 'tee' it into the line feeding to the dual power.
Once that's done, warm the tractor up to the hydraulic oil is reasonably warm.... then with the engine running at a fast idle ~1100 rpm.... you start checking pressure. It should maintain 160-180 psi. It is probably not uncommon for one of those things to only make 150 psi which would not indicate a problem per se but that's still lowish pressure. I run them at the higher end. What you di is test with the DP in low, then in high. Then check with the PTO engaged vs disengaged. If it has MFWD, check with that engaged and disengaged. DO this for every possible combination of PTO/DP/FWD engagement and see what the readings are singly and cumulatively. Also watch to see what the recovery time is on each shift. If it's more than a 2-3 second blip on the gauge then I would say there is an oil supply problem. If the pressure is just uniformly, steadily low then you have a leak somewhere. If nothing you do can raise the pressure.... then remove the lines to the DP/FWD completely and hook the gauge in so that you are only testing the PTO pressure. Then retest the PTO pressures engaged/disengaged. If they improve on both then the problem is forward. If they don't improve at all then you would have a supply problem either in the pump or the regulating valve... There is also an inlet strainer for the PTO/DP/MFWD supply pump. This is a 1/2" square plastic plug to the rear of the main filter. Thread that out and clean it, then recheck the pressures.
In your case I very much suspect you will find the problem is a leak in the DP unit causing a lack of pressure and when you isolate the PTO the pressure will rise.
You need to check the pressure first before you dig into it tho or you're just flailing in the dark and risk spending a lot of money to fix what may not be broken.

Rod

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