L**40 rear hydaulic pressure

[J_J]

SPYDERLK,

Exactly, but he says that the PB still has fluid flow, and the pressure is higher on the remote when using the loader, and that is generally not the case.

He can have flow to the remote at the same time , if that valve is connected in series correctly and the FEL is only using 5 GPM's out of the 8.9 GPM's available.

If all this is true, and the relief for the FEL is working correctly, it should/would limit the pressure.

Kuboman,

How is your plumbing set up to get any flow when the loader is used, except what I said above about the FEL only using half of the pump GPM's?

 

[J_J]

Even though you say the loader is internal, you might have a hyd block that can be configured to take the pump flow and route it, to say the remote first, return the fluid to the hyd block and then on to the FEL.

Then, if the pump is capable of 3200 psi, and the remote is set to 3200 psi, and the FEL valve is set to 2550 psi, anything attached to the remote will operate at the 3200 psi, and anything attached to the FEL and beyond will operate at 2550 psi.

 

[SPYDERLK]

SPYDERLK,

Exactly, but he says that the PB still has fluid flow, and the pressure is higher on the remote when using the loader, and that is generally not the case.

He can have flow to the remote at the same time , if that valve is connected in series correctly and the FEL is only using 5 GPM's out of the 8.9 GPM's available.

If all this is true, and the relief for the FEL is working correctly, it should/would limit the pressure.

Kuboman,

How is your plumbing set up to get any flow when the loader is used, except what I said above about the FEL only using half of the pump GPM's?

I actually wish that mine worked as he describes. Id love to be able to operate all functions without regard to the others, but without a flow spitter or priority valve I see no way to do it from a single hyd source. Mine has a PRV on the remotes that could prevent the significant overpressure he sees.:thumbsup:
larry

 

[SPYDERLK]

Has anyone with a L40 tractor with rear hydraulic outlet tested the pressure? Installed a rear outlet on mine and checked the pressure and had heart failure. It topped out at 3200psi. Seems a lot high to me but was wondering if they are all this way.

How did you connect that outlet to the source flow from the pump??
larry

 

[J_J]

Kuboman,

Do you know for a fact that the internal pump is going directly to the FEL valve?

If I read your first post correctly, this is not factory installation, but you installed this valve and ran the FEL PB out line directly to the remote valve. Where is the PB out from the remote going? Is this when you checked the pressures?

If you put a gage at the input to the remote valve IN port do you read 3200 psi when the valve lever is maxed out, and with or without attachments plugged in?

 

[oldnslo]

Roy,

If he is using fluid from the return port to feed the input to the remote, he would only have remote valve operation when the loader was used.

If the loader/FEL levers were in neutral, he would have no flow to the remote. The PB from the FEL would be going elsewhere.

To see if the one pump is developing that high pressure, install a gage first thing after the pump.

Maybe this is just a test situation/question for us with no good answer available.

Sometimes the Navy electronics instructors would give us an impossible question/situation, just to make us work really hard trying to figure it out, and the only right answer was that it was not possible.

It taught to do some through trouble shooting, and to use all the skills af analysis.

Knowing how something is supposed to work. What is it doing now , and what is it not doing.

Using process of elimination, and starting from the front end or the back end, and all good trouble shooting principles

JJ
my concern is that he does not have PB connected properly. Everything he is describing sounds like a series circuit where the tank port of the first valve feeds pressure to the next. By having the valves connected like this he would have flow to all functions all the time. That is what I asked him to check to see if the FEL system pressure followed his rear remote pressure.

Like spyderlk an you have both stated, there should be NO flow to the rear remotes when he is using the FEL.

 

[kuboman]

I don't have an electronic version of the schematic but this is how I read it and view it.
sump to filter to pump to loader valve with relief to PB port on loader valve to hydraulic block which contains 3pt valve and port for rear remotes. The remote I put on is a factory kit. Identical to the ones that come with it installed.
There is no other source of oil to the 3pt/remotes except from the PB port of the LV. This is what the schematics show and what a visual inspection proves out.
The only way I can see that there is higher pressure at the rear remotes is that there is oil that is bypassing the relief either by design or by a fault in the loader valve. All oil to the remotes/3pt comes from the loader valve. Maybe a check valve is leaking and allowing oil to bypass the relief. Or maybe this is just how they are built. When I talk to the Kobota mechs not one has eveer checked the pressure at the rear remotes as Kubota tells you to set the pressure at the loader valve. So when I mention my concern they all look at me with that dumb look and tell me they never check the back end??:confused2:

 

[kuboman]

JJ
my concern is that he does not have PB connected properly. Everything he is describing sounds like a series circuit where the tank port of the first valve feeds pressure to the next. By having the valves connected like this he would have flow to all functions all the time. That is what I asked him to check to see if the FEL system pressure followed his rear remote pressure.

Like spyderlk an you have both stated, there should be NO flow to the rear remotes when he is using the FEL.

It does say in the manual that there is flow to the PB port with the loader active. And yes I can raise the 3pt and the loader at the same time. Response on both is slower but both will function. When the loader is in a bypass situation the flow to the PB is cut off.
The more I read and mess with this the more I believe that Kubota did not really plan on rear remotes.

 

[Chilly807]

You did say you'd checked another 40 series machine on the dealer's lot and it was delivering only 2500 psi at the rear outlet, right?

If that's so, either you have something installed wrong or there's a problem with your tractor's pre-existing hydraulic system.

As I understand it, you had 2 rear remotes already installed (factory), and added a third remote yourself. If that's the case, do you have 3200 psi on all three remotes, or only on the latest addition?

Sean

 

[J_J]

Tell me again if this is correct.

If the gage is installed and left in a tee at the IN port, you get 2550 psi when you max out the loader, and when you operate the 3pt, you get 2550 psi on the gage. and when you activate the remote, you get something higher.

If your remotes are installed correctly, the FEL valve relief controls the max pressure limits. Unless, you set a lower relief psi on a valve.

Since you tested the setting on the FEL relief, we can assume that the FEL relief will work the same when any other valve lever is activated.

The FEL valve relief is probably not passing any other fluid, because it was tested, it is regulating the hyd pressure at 2550 psi and this pressure should be felt through the hyd operating system.

The only other generated psi increase I can think of is with intensification, but I don't think it applies in this situation.