3-Point Hitch M7040 relief vave(s) setting. How FEL valve affects 3pt hitch operation

[Dave M7040]

I have some info owner's of M7040 with FEL may find interesting.
I was having trouble lifting my large heavy snow blower (when the blower was covered in snow and ice) on the 3pt hitch in spite of using the lift arm holes which provide the greatest strength.
My shop manual provided instructions for setting the 3 pt relief valve which is located near the rear remotes.
I bought a new gauge and hydraulic fitting to plug the gauge into a remote port. Total cost for the gauge and fitting was approximately $30 which is a great investment
For the test the tractor is to be run a full revs and then the remote valve activated and a reading taken from the gauge.
In spite of adjusting the relief valve to its maximum position, I was reaching about 2,400 psi which is approx 400 psi below the 2,800 psi setting in the shop manual.
I spoke with the dealer's mechanic some time ago about this and learned that the FEL relief valve could be the cause.
My health does not permit me to crawl under the tractor so I had the mechanic come to my place this week for the 300 hr service.
First he double checked the reading I was getting on the remote and then began to adjust the FEL relief which you access after removing the metal guard around the FEL valve.
Soon the remote valve was reading almost 3,000 psi.
He explained the hydraulic circuit this way.
The pump has two sections. One feeds the power steering and has an independent hydraulic circuit. The other section feeds first the FEL valve and then through a power beyond port the flow goes to the rear remotes and 3 pt. If the FEL relief valve is set below the factory 3,002 psi the pressure available for the 3 pt and rear remotes is reduced.
I have not had time to attach the snow blower nor to try to lift the front wheels using only the bucket curl cylinders.
The workshop manual for the tractor does not show a hydraulic circuit for the FEL and the shop manual for the FEL is, for my level of knowledge on hydraulics, not informative enough about how the two systems integrate once on the tractor.
Dave M7040

 

[grader guy]

Hi just wondering where you got the parts to check the pressures. I would like to check the pressures on my m7040 because I have a 92'' normand blower going on my machine this winter. Thank you. Matt

 

[Dave M7040]

The setup is very simple.
A gauge like this one from Northern Tool.
Valley Instrument Grade A 4in. Stem Mount Glycerin Filled Gauge — 0-3000 PSI | Hydraulic Gauges| Northern Tool + Equipment
And a hydraulic coupling fitting like you would have on a hose being plugged into a rear remote valve together with the adapters to match up the threads.
A local shop selling hydraulic hose and similar would have all you need.
The fitting on the gauge is plugged into one of the remote ports or into a port where a FEL hose connects and then the lever pulled to direct flow to that port.
The tractor needs to be a full revs and you will hear the engine strain as the pressure builds and then relief valve opens. The maximum pressure reached needs to be observed by eye.
Dave M7040

 

[Dave M7040]

Here is an actual picture of my relief valve test gauge and fitting

Dave M7040

 

[grader guy]

Here is an actual picture of my relief valve test gauge and fitting

Dave M7040

Thank you for the response! I am going to have to get one of those to see what my tractor is producing for pressure.

 

[kennyd]

Well sell a ready to go test gauge kit, and have a video posted on how to test pressure on a tractor.

Ken's Bolt on Grab Hooks <<Hydraulics>>