310 john deere hydraulic problem

i have a straight 310 jd backhoe has been working great till the other day coming back from loading hay with it the steering got stiff for just a second, the it was fine. Went out today to move some gravel with it hydraulics are slow and weak steering is stiff and it has also lost its brakes, was serviced around a month ago new sump screen and transmission filter with oil change as well. What gives I'm slightly confused what's going on. thanks for any replies

Put a gauge into the reverser control valve and check trans pressure. With a 200-300 lb gauge on a hydraulic hose long enough to tie it to the
ROPS , you can watch pressures while operating the reverser lever. Always shift gearshift levers to neutral or park. I like to run the
stabilizers to just raise the machine off the ground [just incase]. Run the machine at 1/3 to 1/2 throttle and shift the reverser lever to see
what the gauge shows. This pressure is trans. operating pressure and charge pressure for the hydraulic pump. Should read 130- 150 lbs. Run the
throttle from idle to 3/4 speed and watch the gauge as you do this. If there is a lot of variation in pressures , I'd put my money on the filter
relief valve partially open due to a chip of foreign matter holding it open a tweek. It doesn't take much. I showed a customer the tiny flake of
crap I took out of his filter relief valve and he as much as called me a liar. If you drain the trans , and remove the vertical filter , look up
in there . You will see a shiny chromed round valve spool . take the plug out and carefully pry the spool out and lay it out on a clean
rag/towel. Take it apart and lay it out as you disassemble it. The poppet should be seated fully inside the spool. Wash it out with brakecleaner
and reassemble. install valve , install filter add oil and try it again..

Thank you for your reply I did get a chance to check the pressure as instructed at a idle it shows 65 pounds, at half throttle still shows 65 pound at full throttle still 65 pounds pressure, moveing the
reverser lever makes no difference in pressure reading. Any other advice would be appreciated.

I think I would still look at the filter relief valve being stuck wide open. 65 lbs isn't much oil pressure. BUT , It could also be a sign of internal problems with pump or valving in the reverser control valve.. It would be affecting the overall performance not a range

And again thank you for the reply the next day I have off work will pull the valve out and clean it and reinstall, and go from there.

I just of thought something else to check.. See if the roll pins on the clutch pedal cross shaft are broken or worn so the shaft doesn't have
the proper rotation going to the reverser valve. Worn or broken roll pins there would act as if the pedal was pushed in , dumping oil to sump. By
dumping oil back to sump, the front pump could be starved of charge pressure oil..

cleaned the filter relief valve didn't see anything in it, reinstalled it no change still low pressure at the test port, the linkages are tight not loose or anything. For a backhoe this old it has very few
hours on it. In a year it gets less then hundred hours on it right now it only shows around 4600 hours and those are correct, it was bought when it only had around 2000 hours on the machine when it was bought
from are neighbor, he installed septic systems before he passed away

Another possibility may be a problem with the De-stroke valve on the hydraulic pump. It lessons the hydraulic load when starting the engine . Not knowing which pump you have , JD used several versions , with manual and electric valves. The following link for JD Parts Online may be of some help : https://partscatalog.deere.com/jdrc/ . Put 310 in the search, look at PC 1226, section 50 Hydraulic System has the various choices .

This machine does not have a de-stroke valve, really no need for one it doesn't get very cold around this area so hard starting isn't a problem, but thank you for the reply I'm up for any suggestions.

I haven't worked on one of these backhoes in about 20 years. I'm kind of going by memory. I sold all my tech manuals , service truck , and test equipment when I retired. I guess I got stupid from inactivity. There is a pressure regulating valve on that reverser control valve, but I don't remember which one it is. Shim adjustable or maybe stuck in it's bore or broken spring.

I ordered a repair manual, so i could understand some of the things your talking about should be here in a day or two, thank you again for your input.

Actually a question for Roy, you are far more knowledgeable than I am , but in the old 2010 backhoes their was a diverter valve, for priority steering. When that got trash in it or the spring behind it broke, every thing went crazy. Some where in his system their should be the same type of valve, but I don't know where it is. Do you think it could be affecting the system as the old 2010 did ?

There is a pressure control valve on the side of the trans case. This is a closed center system , I think the older tractors used a gear pump
[open center]. It probably wouldn't have anything to do with the transmission drive , but would have to do with hydraulics. On the 310-410
machines the steering is just teed into the main pressure line that feeds the pressure control valve. Closed center system is a piston powered
pump that stops flow when any function is unused. stand-by pressure is maintained as long as no lever is pulled or steering actuated. In the
pressure control valve there is a poppet that maintains a certain oil pressure [ depending on serial number ] for the steering when raising the
front loader, so you can steer and raise the loader at the same time. Someone mentioned the de-stroking solenoid as a possible problem. That
wouldn't have anything to do with actual transmission function.

Thanks Roy, I'm not as familiar with the 310 closed system as you are. After all he has checked, I can only think of one other possibility. Correct me if I am wrong, since it was serviced not long ago, could it be that some where air is entering the system ? Air doesn't compress like the fluid does, if that's not a possibility I'm out of ideas. I hope he will be able to figure it out and post back the solution. Again thanks for the reply.
Jo

Air entering the system will show up as a leak when not operating or when operating, will show up as foamed up oil. Air will be expelled from the
system within minutes of start up. Usually air will make pump noises such as squawking and loud rattle noise. Pressure oil from trans. charge
pressure will help force air from system. When the splines are worn the pump will emit a rattling noise when hydraulics aren't being used. This
is common on these backhoes. I've pulled my hair out on more than one of these backhoes.

Finally got a repair manual today, looked at the hydraulics diagram decided to try something, took the line loose that feeds the brakes with the machine running oil just drips out just a slow drip no pressure at all, a drop about every four seconds, I don't know if that gives you anymore useful information or not, thanks again for your input.