L1801 hydraulics problem.

[Yann]

Hello,
My name is Yann, I am french but I live in Kyrghizstan (central Asia) where I have a horse ride business.
To help me in caring of my horses I bought a "gray market" L1801 (Zen Noh).
As I plan to be able to work with it quite a long time I imediately made all oil changes, Axes, Gear, Engine, and greased all the needed places.
I also gave it a good wash (it had some 15 kg of oily dirt everywhere...).
The engine had the standart plug problem on the valve shaft that went off, as a result no oil pressure in the engine. I fixed that in first place.
I also made a roll bar and filled up the tires with antifreeze (it has a front loader).

The problem is with the front loader. The hydraulics pump must be ok as the loader works well just after start.

But if I want the loader to work I have to keep the rear three point lever in max hight position (I fix it in position with the bolt). But I have noticed that after some work with the loader the rear three point than works very slowly, and some times not at all...

My thinking is that some connection is not in the wright place, all the oil flow goes through the rear three point system instead of directly to the loader controls, but I can not find how to make things wright.
The tractor came like this from Japan, nothing was changed, and it seems that it was not used for a couple of years.

I changed the gear oil, but did not clean the filter (if someone could give me the exact steps to do it I would be gratefull).
In the attached file a picture of the hydraulic system.

Thanks for advices!

P.S. Sorry if my english is not so good, I'm french...

 

[eserv]

It is working correctly right now considering how it is plumbed. For the three point hitch to work properly though it needs to have a shutoff valve in the hose that leads from the TPH to the loader valve that you shut off when you want to use the TPH.. This was a common way to plumb them. It would work better if the oil went from the line you have marked "from pump" to the loader valve first then returned to the TPH where it is attached now. Ensure that there is a relief valve in the loader valve if you change it though because if there isn't you can deadhead the pump and damage it!

 

[North Idaho Wolfman]

You can fix it to be right, by connecting the loader valve to the round cover on the right side of the picture (left side of the tractor).
I just requires an adapter plate, I'll see if I can find it for you.

 

[Yann]

It is working correctly right now considering how it is plumbed. For the three point hitch to work properly though it needs to have a shutoff valve in the hose that leads from the TPH to the loader valve that you shut off when you want to use the TPH.. This was a common way to plumb them. It would work better if the oil went from the line you have marked "from pump" to the loader valve first then returned to the TPH where it is attached now. Ensure that there is a relief valve in the loader valve if you change it though because if there isn't you can deadhead the pump and damage it!

Thanks for your prompt answer!
I think I will try to connect the loader as you say.
The point that worries me is what you say about the relief valve, I can't see any in the loader system. And there is no chance I might find one here... the closest Kubota dealer is in Russia, 4000km... If I work acurately, without pushing when the cilinders are at max or min extension, will it be enough to "save" the pump??? how does a relief valve look like, maybe I could try to have one from a chineese tractor (if they do use some...).

 

[Yann]

You can fix it to be right, by connecting the loader valve to the round cover on the right side of the picture (left side of the tractor).
I just requires an adapter plate, I'll see if I can find it for you.

Thanks for your answer!
As it might be quite impossible for me to get anything for a Kubota here I have a question: is the round cover you mention (the one connecting the oil income to the tractor) thick enough to be drilled and have a thread made directly in it? It would allow me to have a direct output and connect the loader directly to it. I just do not want to dismantle all before I am sure I can do something with it!
If not than I might be able to have an adapter plate made by guys here, I would just need a picture of it to have an idea how it looks like.(in this case would it not be more logical to connect it to the pump exit?)

 

[North Idaho Wolfman]

You would have to have a new plate made, as that plate on there has an internal passage to let fluid move from one side to the other, or as you said, just cut the line coming from the pump and add ends to be able to connect the loader valve to those ends.

Either will work the same.

 

[Yann]

You would have to have a new plate made, as that plate on there has an internal passage to let fluid move from one side to the other, or as you said, just cut the line coming from the pump and add ends to be able to connect the loader valve to those ends.

Either will work the same.

Ok, thanks for your help!

 

[Yann]

Hi all,
I have finally decided to add a relief valve in the system.
I then have the following question, what is the nominative working pressure for this pump? (I plan to put the valve at the power exit of the pump).
On the net I haven't found a precise answer (from 80 bar to 200...).
As I will have to adapt a valve from another tractor (I have access only to either Chinese or Russian spare parts) without the working pressure info I cannot do anything.
I have added a picture of my pump, in case it might help.

 

[Vigo]

I think you might be operating on a misunderstanding. ALL tractor 3pt systems have a relief valve somewhere. A hydraulic system with no relief valve will build pressure until something blows up the very first time you hit the limits of its travel, or exceed its weight capacity.

So my question is, are you adding an external relief valve because you have decided it is too complicated to plumb the loader valve in a way that takes advantage of the relief valve that is already in the 3pt system? I could understand that motivation but want to make sure that’s a correct interpretation.

I have not actually researched the factory relief pressure on your tractors 3pt but i have noticed a pattern that it seems the relief pressure is tailored to make the 3pt lift what that tractor could comfortably handle without tipping back or losing steering control (assuming no FEL), and that the upper limit of factory settings from back then was in the low 2000s psi range. Im only referencing the factory 3pt relief pressure because it’s evidence that ‘if Kubota made it that way, it’s fine’. So probably 1500-2000psi is fine.

How strong that would mak your loader depends on the loader itself.. cylinder sizes, geometry etc.

 

[TheOldHokie]

Hi all,
I have finally decided to add a relief valve in the system.
I then have the following question, what is the nominative working pressure for this pump? (I plan to put the valve at the power exit of the pump).
On the net I haven't found a precise answer (from 80 bar to 200...).
As I will have to adapt a valve from another tractor (I have access only to either Chinese or Russian spare parts) without the working pressure info I cannot do anything.
I have added a picture of my pump, in case it might help. View attachment 100190

I have no idea what your motivation is but 2000-2400 PSI (135- 160 BAR) is the range you are after. You can use a general purpose 3 port inline relief valve - it does not need to be tractor specific. I would also suggest one that can be externally adjusted.

Dan

 

[Yann]

I think you might be operating on a misunderstanding. ALL tractor 3pt systems have a relief valve somewhere. A hydraulic system with no relief valve will build pressure until something blows up the very first time you hit the limits of its travel, or exceed its weight capacity.

So my question is, are you adding an external relief valve because you have decided it is too complicated to plumb the loader valve in a way that takes advantage of the relief valve that is already in the 3pt system? I could understand that motivation but want to make sure that’s a correct interpretation.

I have not actually researched the factory relief pressure on your tractors 3pt but i have noticed a pattern that it seems the relief pressure is tailored to make the 3pt lift what that tractor could comfortably handle without tipping back or losing steering control (assuming no FEL), and that the upper limit of factory settings from back then was in the low 2000s psi range. Im only referencing the factory 3pt relief pressure because it’s evidence that ‘if Kubota made it that way, it’s fine’. So probably 1500-2000psi is fine.

How strong that would mak your loader depends on the loader itself.. cylinder sizes, geometry etc.

Thanks for your answer.
My point is to add a valve anyway to the system. When I push either the loader or the 3pt lift to the maximum extension/load the pump starts to make a weard hi tone noise, which for me sounds like over pressure. I changed the pump but the noise is the same (the sound comes 100% from the pump). As I was unable to find a relief valve anywhere in the power lines and loader controls I think there might be none.
I will then search for a valve around 130-150 bar (hopefully I will find one where the pressure can be set as needed), add it to the system and see if it gets better.
I will also try to check the pressure the pump gives out in real time, to be sure it's not just a worn out pump issue (in this case both my pumps would be in the same wear status, which is quite unlikely).

 

[Yann]

I have no idea what your motivation is but 2000-2400 PSI (135- 160 BAR) is the range you are after. You can use a general purpose 3 port inline relief valve - it does not need to be tractor specific. I would also suggest one that can be externally adjusted.

Dan

View attachment 100303

Thanks!
Will try this (I explained my motivation in my upper message).

 

[TheOldHokie]

Thanks for your answer.
My point is to add a valve anyway to the system. When I push either the loader or the 3pt lift to the maximum extension/load the pump starts to make a weard hi tone noise, which for me sounds like over pressure. I changed the pump but the noise is the same. As I was unable to find a relief valve anywhere in the power lines I think there might be none.
I will then search for a valve around 130-150 bar (hopefully I will find one where the pressure can be set as needed), add it to the system and see if it gets better.
I will also try to check the pressure the pump gives out in real time, to be sure it's not just a worn out pump issue (in this case both my pumps would be in the same wear status, which is quite unlikely).

A more traditional solution is to use a loader valve with a built in inlet pressure relief. The loader valve then acts as the main system relief.

Dan

 

[Yann]

A more traditional solution is to use a loader valve with a built in inlet pressure relief. The loader valve then acts as the main system relief.

Dan

At the moment I see no point in changing my loader control system, adding a valve in the system between the pump and the loader should be enough. Plus the effect will then be on all the hydraulics, including 3pt.

 

[TheOldHokie]

At the moment I see no point in changing my loader control system, adding a valve in the system between the pump and the loader should be enough. Plus the effect will then be on all the hydraulics, including 3pt.

I understand your reluctance to change the loader valve but you seem to have a misunderstanding of the hydraulics. A loader valve with inlet relief protects ALL of the systems and is equivalent to your proposed inline relief. Kubota used that scheme for years.

Dan

 

[Yann]

I understand your reluctance to change the loader valve but you seem to have a misunderstanding of the hydraulics. A loader valve with inlet relief protects ALL of the systems and is equivalent to your proposed inline relief. Kubota used that scheme for years.

Dan

If this is an easier solution I will of course keep it in mind, my question than would be: does the way the loader controls are connected to the hydraulics of the tractor have an importance? Mine are connected this way (picture joined), and I think it is a weard way to connect them as if I do not block my 3pt in upper position I have no pressure to the loader controls. But as there are mo other outlets on the line coming from the pump the options are quite limited...
I plan to cut the main power line coming from the pump, to add a connection and use it to connect the relief valve and the loader. If my thinking is good I would than have two separate circuits, one for the loader and one for the 3pt. Am I wright?
And the relief valve will, as you say, work for all the system.
It is my first deal with "complicated" hydraulics, I've worked only with dump truck hydraulics before, it's much simpler .

 

[TheOldHokie]

If this is an easier solution I will of course keep it in mind, my question than would be: does the way the loader controls are connected to the hydraulics of the tractor have an importance? Mine are connected this way (picture joined), and I think it is a weard way to connect them as if I do not block my 3pt in upper position I have no pressure to the loader controls. But as there are mo other outlets on the line coming from the pump the options are quite limited...
I plan to cut the main power line coming from the pump, to add a connection and use it to connect the relief valve and the loader. If my thinking is good I would than have two separate circuits, one for the loader and one for the 3pt. Am I wright?
And the relief valve will, as you say, work for all the system.
It is my first deal with "complicated" hydraulics, I've worked only with dump truck hydraulics before, it's much simpler .

Yes it matters. This is a 4 year old thread which started with your loader connection. I assumed you had taken the original advice and replumbed the loader off the front outlet block. Plumbed as you ßtill have it the loader valve will not protect the 3pt.

Dan

 

[Yann]

Yes it matters. This is a 4 year old thread which started with your loader connection. I assumed you had taken the original advice and replumbed the loader off the front outlet block. Plumbed as you ßtill have it the loader valve will not protect the 3pt.

Dan

Since I first opened this thread I did not change anything as I did not get the time.
I plan to do so now.
Can you tell me if the main hydraulic power line (on picture) is thick enough to be mig welded? Or should it be tig?

 

[TheOldHokie]

Since I first opened this thread I did not change anything as I did not get the time.
I plan to do so now.
Can you tell me if the main hydraulic power line (on picture) is thick enough to be mig welded? Or should it be tig?

Neither - use compression type hydraulic tube fittings.

If you are going to cut the line you can feed your loader valve from the pump half and then return pressure (the high pressure carry over / power beyond port on the loader valve) to the other half of the line. That is equivalent to using the factory outlet block. Then no need for the inline relief.

Dan

 

[Yann]

Neither - use compression type hydraulic tube fittings.

If you are going to cut the line you can feed your loader valve from the pump half and then return pressure (the high pressure carry over / power beyond port on the loader valve) to the other half of the line. That is equivalent to using the factory outlet block. Then no need for the inline relief.

Dan

Thank you very much for all your precise and useful answers!
I will now assemble all the needed parts, it might take a while as I am quite restricted in my choices here
Thanks again for all!