L**40 rear hydaulic pressure

[J_J]

If the relief in the FEL is a pilot operated relief, is the pilot provided by the FEL or the pump flow?

If it is FEL pilot operated, and you are not using the FEL, the remote valve could go to pump pressure, because someone forgot about a relief valve for the remote.

I believe he said the 3200 psi was only when deadheading the remote. As soon as you operate the FEL, the pressure drops, or goes to zero, and that would be logical.

I would be curious if the other 40 series tractors use that loader valve and circuit.

If you only operate the 3pt with a max load what pressure does it relieve?

If nothing in the circuit can intensify pressure, then it has to be pump pressure on the remote valve, with no relief in the circuit.

If the 3pt is relieved at 2550 psi, then the FEL relief controls the series circuit.

 

[oldnslo]

You and me both.
Well like the Kubota tech said "that's just how it is".
Since they did sort of duplicate my situation with another tractor (cabbed) there is in my opinion a design deficiency.
I am quite sure mine is operating as it was designed to. Just wish someone could explain what is happening. In the mean time I will make sure any implement has good hoses.

Since we have tried everything else, just out of curiosity have you ever noticed if the 3PH moved or changed position during any of the tests? Since you have draft and position i would suspect they arms lift as soon as tractor starts.

Since all we have to lose is more hair, lower the 3PH and then operate the RR, do the arms move? With curl or dump function dead headed will the 3PH raise?

If yes, try dead heading RR and raise 3PH.

Roy

 

[oldnslo]

If the relief in the FEL is a pilot operated relief, is the pilot provided by the FEL or the pump flow?

If it is FEL pilot operated, and you are not using the FEL, the remote valve could go to pump pressure, because someone forgot about a relief valve for the remote.

I believe he said the 3200 psi was only when deadheading the remote. As soon as you operate the FEL, the pressure drops, or goes to zero, and that would be logical.

I would be curious if the other 40 series tractors use that loader valve and circuit.

If you only operate the 3pt with a max load what pressure does it relieve?

If nothing in the circuit can intensify pressure, then it has to be pump pressure on the remote valve, with no relief in the circuit.

If the 3pt is relieved at 2550 psi, then the FEL relief controls the series circuit.

J_J
the WSM does not state what type of relief valve is used. What does not make sense is that if it is the first valve in the supply line, how would it produce two different pressures.

Agree I don't see anything in the circuit that should intensify pressure except possibly raising the FEL when empty. But that takes me back to why the FEL relief does not relieve when using rear remotes.

I asked Kuboman to try running the 3PH with curl or dump dead headed. If circuitry is plumbed per the schematic the 3PH should not move. If it does now we are back to how is the tractor plumbed vs what the schematic shows.

more :mur::mur::mur: to follow.

 

[kuboman]

Since we have tried everything else, just out of curiosity have you ever noticed if the 3PH moved or changed position during any of the tests? Since you have draft and position i would suspect they arms lift as soon as tractor starts.

Since all we have to lose is more hair, lower the 3PH and then operate the RR, do the arms move? With curl or dump function dead headed will the 3PH raise?

If yes, try dead heading RR and raise 3PH.

Roy

I have done that and with the curl deadheaded the 3pt will not raise and with the rear remote deadheaded it will not raise. It will raise with the loader lift arms until they bottom out and bypass the relief.

 

[dfkrug]

...we are back to how is the tractor plumbed vs
what the schematic shows.

This is where I am. Although Kubota is a great company, it is not beyond
imagination that the docs to not represent this machine. AND, it is very
hard to verify the plumbing connections when some of them are hidden
inside manifolds.

 

[oldnslo]

I have done that and with the curl deadheaded the 3pt will not raise and with the rear remote deadheaded it will not raise. It will raise with the loader lift arms until they bottom out and bypass the relief.

thanks Kubo,
Just more confirmation that oil is flowing the way the schematic shows. Still doesn't explain the higher pressure though. I wish you where a few hundred miles closer because then we at least could beat our heads on the same wall

Everything points to something wrong in how the relief senses pressure but I sure don't see how or what it is.

Do the rear remotes have an option of installing a relief valve? I.e. Does the valve inlet have a plug in the cavity Vs a relief valve. This would at least give you the option of having pressure limit control at the rear valve. Does the inlet section on the rear look similar to the inlet section on the front valve? Not sure if Bota uses common valve components or not.

Not a cure but would be fix that would require no plumbing changes.

Roy

 

[kuboman]

thanks Kubo,
Just more confirmation that oil is flowing the way the schematic shows. Still doesn't explain the higher pressure though. I wish you where a few hundred miles closer because then we at least could beat our heads on the same wall

Everything points to something wrong in how the relief senses pressure but I sure don't see how or what it is.

Do the rear remotes have an option of installing a relief valve? I.e. Does the valve inlet have a plug in the cavity Vs a relief valve. This would at least give you the option of having pressure limit control at the rear valve. Does the inlet section on the rear look similar to the inlet section on the front valve? Not sure if Bota uses common valve components or not.

Not a cure but would be fix that would require no plumbing changes.

Roy

You might have me on that. I understood the valve block just had a check valve in it. I did not remove anything before I mounted it on the tractor, I will take a look to see if it is accessible without removing it.

 

[Chilly807]

To explain the test results, all I can see is that the AUX valves are
connected BEFORE the FEL valve, and the AUX valve block has its own
RV, which is set at 3200psi.

This is what I was thinking at first, too. But if that were the case, unless the FEL relief is isolated from the rest of the system as soon as the pressure rose above 2550 it would open and limit pressure throughout the system, all the way back to the pump outlet.

I think the key to this is where the FEL relief is sensing the pressure. If the most you can get at the FEL ports is 2550, it's internal to that valve and disregards everything else. The main safety valve, set for 3200 psi, is what's limiting the rest of the system here.

OK, let's consider for a moment what is protected, and what isn't. The FEL is fine, it's limited to 2550. Assuming the 3 point is capable of containing 3200 psi, it's fine. The only problem, at least so far, is the pressure out of the rear remotes, which is also at 3200 psi.

Maybe we should be looking at the new rear remote valve, and whether or not it has an internal relief. If it does, and I suspect that IS the case, it's just not set correctly. That's why Paul's tractor, and junkyarddog's too, are both at 2300-2500 psi, either because they were adjusted correctly at the factory, or they may have a different remote directional valve.

As I understand it, kuboman bought the kit from a Kubota dealer, which consisted of hard lines, a set of quick disconnects, the adapter plate, AND a valve assembly with directional control lever. I think there should be a relief valve built into that valve body, to limit the pressure output at the remotes. I guess it's possible that there are a couple different options available when you order the remote kit, and one of them doesn't have an internal relief.

I don't really understand the logic behind this set up. Why would Kubota build a tractor without a main relief valve? They are assuming that any add-ons will have their own internal or external reliefs, because obviously in this case the FEL valve is not controlling the pressure downstream in the system. It must have something to do with where that relief valve is taking it's pilot(sensing) pressure from, as we're starting to see.

Sean

 

[Leejohn]

Well boys forget everything I said!!!!! I had my L4240 in the shop and ran some test. This is what I came up with.
Note that all the test were done at the rear remote in the up and down ports. Also the 3pt would not go up with any other valve in use.
1st was to test the psi at RM with boom on the floor, it was 2700psi. When I went up with the boom psi went over 3000psi.
2nd Boom off the floor psi was 2700 but with rm in use, boom would not come down but the psi stayed at 2700.
3rd Boom off the floor psi at 2700 the bucket would go up psi would go up maybe 50psi. When bucket was going down psi would stay the same. It was working the way it should.
The 3000+psi only showed with the boom in the going up mode. One thing that I couldn"t understand, if the boom well go up why well it not come down?
I have looked at the drawings of the loader valve all morning and can't see anything why this should happen. Makes me think, are the drawings and schematics right iin the manual. How could one find out if there is a update for the manual.

 

[J_J]

Here is a post by hayden about his 5740, it was reading low pressure.

http://www.tractorbynet.com/forums/owning-operating/111787-pimp-my-tractor.html#post1278432

I am thinking that the banjo fittings can be replaced with reg fittings.