Hydraulic Fitting questions

[BoB F]

Hi... I'm trying to boost the pressure of the hydraulics on my older B7800, both loader AND backhoe. I know that the backhoe connection is 4000 series Parker. I have found a nipple (3/*"NPT Female) and brass adapter for the 3/8"NPT to 1/4"NPT (both male ends) to connect my gauge to ONE side of the line coming back for the backhoe. When separated, I probably should NOT run the tractor due to the pressure coming back through these hoses... am I correct? I would have the gauge "plugged" into the female quick disconnect (Parker 4050-3p), but do I need to plug off the male end of the hose? Perhaps not since it's seems to 'need' to be plugged into the female to push that little pin in, but not sure. Also, for the loader, I have included pictures of the main valve... the fitting are hard plumbed and not quick disconnects. There are TWO very similar FITTINGS screwed into the mail loader valve besides the hoses. One, I believe, has the bypass spring, etc. in it. I believe I can 'shim' that with some special shims from Kubota to increase pressure (seen this online), but my question is; WHICH of the two has that bypass spring in it? Anyone know which one?

 

[North Idaho Wolfman]

Those are the detents (red x's) not the pressure relief valves.
DO NOT remove them.
The disconnects (green) is where you would connect a pressure gauge to to measure it.

You will need to set the tractors relief valve before the loader relief valve can be set.
On that model it's extremely difficult to change the pressure relief setting as you will need to disassemble the top of the transmission to get to the valve, in order to do it.

This is the pressure relief on that loader valve, tread wisely.

 

[TheOldHokie]

Hi... I'm trying to boost the pressure of the hydraulics on my older B7800, both loader AND backhoe. I know that the backhoe connection is 4000 series Parker. I have found a nipple (3/*"NPT Female) and brass adapter for the 3/8"NPT to 1/4"NPT (both male ends) to connect my gauge to ONE side of the line coming back for the backhoe. When separated, I probably should NOT run the tractor due to the pressure coming back through these hoses... am I correct? I would have the gauge "plugged" into the female quick disconnect (Parker 4050-3p), but do I need to plug off the male end of the hose? Perhaps not since it's seems to 'need' to be plugged into the female to push that little pin in, but not sure. Also, for the loader, I have included pictures of the main valve... the fitting are hard plumbed and not quick disconnects. There are TWO very similar FITTINGS screwed into the mail loader valve besides the hoses. One, I believe, has the bypass spring, etc. in it. I believe I can 'shim' that with some special shims from Kubota to increase pressure (seen this online), but my question is; WHICH of the two has that bypass spring in it? Anyone know which one? View attachment 158542 View attachment 158542

To test presdure you just connect gauge to backhoe supply and start tractor. Thats the pressure for ALL valves in the system.

I looked at the loader valvd parts list and it does not look like that relief is adjustable

Dan

 

[North Idaho Wolfman]

To test presdure you just connect gauge to backhoe supply and start tractor. Thats the pressure for ALL valves in the system.

I looked at the loader valvd parts list and it does not look like that relief is adjustable

Dan

I'll beg to differ with you on both counts.
#1 On this model there is no pressure relief valve before the BH loop so deadheading the system is a very likely scenario.
#2 If the relief is not adjustable, why do they have mutiple listings for the shims?

 

[TheOldHokie]

I'll beg to differ with you on both counts.
#1 On this model there is no pressure relief valve before the BH loop so deadheading the system is a very likely scenario.
#2 If the relief is not adjustable, why do they have mutiple listings for the shims?

View attachment 158561

Let the fun begin

1. The losder is the the primary system relief on that tractor/loader combination. It has to be to prevent fully deadheading the pump at the loader or backhoe which are upstream of the 3pt relief. The loader relief sets the max pressure the loader, backhoe, and 3pt can ever see. It also prevents damage to the pump by unloafing to tank when testing as I described. No danger deadheading the pump at any point downstream of that loader relief.
2. There were miltiple valves used on that loader. The one I looked up has a cartridge relief. So that adjustibility seens to depend on which loader valve he has

Dan

 

[North Idaho Wolfman]

OK hear ya on loader relief valve location, I get that.

I can tell which valve he has by the detents.
It's a 4 position valve.