Rear hitch hydraulics with front loader help

[spikey_mern]

Hiya

I've recently purchased an old Iseki TX2160 and am slowly working through the obvious faults, servicing etc and trying to make sure it's working as it should be (as much as possible for this old machine!). The tractor has both a front loader (I believe it's one from a Kubota) and a backhoe (d200). I've removed the backhoe (which is PTO driven, has its own hydraulics) and am investigating the 3 point hitch. The previous owner had the arms but I believe the backhoe has been on for many years.

Anyway, the problem I'm getting is that the arms will go down, but there's barely any pressure to bring them back up again - UNLESS I raise the front loader first, then while lowering it I then also put the rear control lever into raise. Then it goes up fine, which to me makes me think all the hydraulic pressure is going through the FEL.

I'm fairly competent at DIY in general but hydraulics and tractors are new to me so please be nice

Anyone able to help with some things to try? Here's some photos of the different bits

Under the seat, this block has two pipes, one must be delivery and the other return which go to the FEL block:

Just below you can also see what I think is the high pressure line coming from the hydraulic pump at the front of the tractor

And then at the side of the loader, here's a few shots of the control block. The two pipes from that block above come in and go out either side, and then there's two control outlets for the loader lift/drop and bucket curl/uncurl, and there's a 5th one that goes off to a spool valve? at the back of the tractor for an implement at the back

Any help would be greatly appreciated - I've read about pressure relief valves etc but I'm coming up short understanding exactly what's going on here on my tractor, as there's no diagrams I can find that match my setup

Cheers

Martin

 

[LD1]

Pressure relief is likely fine if the loader raises and lowers.

So aside from the obvious 4 hoses that go to raise/lower and dump/curl you are saying you have THREE other hoses on your loader valve?

Those are likely supply/pressure (P), Power beyond (PB) and return/tank(T)

Look and see if anything is labeled and where exactly each hose is going.

The PB hose should go on to feed the 3PH. IF there is a remote valve at the back of the tractor, the PB may feed it then come out of it to feed the 3PH.

The P hose should supply pressure to the loader valve pretty much direct from the pump....but it may go through a manifold block first.

The T hose should go straight to the tank.

With PB on the loader....the ONLY time the tank hose gets flow/pressure is when the loader is being moved. Otherwise the fluid ONLY comes out the PB.

So its possible they hooked the T line to feed the 3PH instead if the PB. Which would explain why the 3PH only moves when you move the loader.

 

[spikey_mern]

Thank you @LD1 for that, given me plenty to go check - I did see a P on the outside on one side, so I'll try to squeeze a phone camera round the other side. Just for my understanding then, I assumed there was always fluid flowing round the system, but from what you said about there not being anything going to tank unless one of the levers is activated - does that mean that a hydraulic circuit isn't sending anything round unless it's called for? Eg it just sits at pressure?

Thanks

Martin

 

[spikey_mern]

Ok, so one side is P, the other side is T. There isn't a PB. The line other than the 4 going to the front loader lift and curl, is on a third joystick lever going to a quick connect at the rear of the tractor, I guess a one way valve for a rear implement. The thing that's confusing me is how the T line is working. E.g. it must be trying to return fluid to the tank, but the port it's going to appears to be the pressure line into the rear 3PH. I also don't see any blanked holes where a return line might be plumbed in. It's clearly worked like this for many years though, just not had a need for the 3ph I guess.

 

[Cataclysm]

Did the FEL work properly before you removed the rear BH?

 

[CADplans]

Think of it like two garden hoses,, fluid goes in the first hose,, if the end of the first hose is not connected into the second hose, no fluid goes into the second hose.

Your system is currently connected such that the hose feeding the 3PH only gets fluid when the lever is actuated.
for the 3PH to work the way you want,, the correct hose needs to be connected, supplying oil at the proper time.

The power beyond is a method of protecting your pump.
If connected wrong, the two relief valves (loader and 3PH) stack together, doubling the pressure the pump is required to supply.

This "doubling" of the pressure either cracks the pump, blows the pump seal, ,,, or worse!!

If you do not feel you are comfortable connecting the hydraulics correctly,,
it may be REAL cheap to pay a hydraulics shop to connect it for you.

Trust me,, the bill at the hydraulics shop is WAY less than the cost of having broken pump parts laying on your driveway.

 

[spikey_mern]

Did the FEL work properly before you removed the rear BH?

Yeh, all still works fine. Backhoe is only connected to frame and PTO, not into the tractor hydraulics. I've been reading @chrismac long post and it looks like he had the same triangular block under the seat. But then it also fed another set of spool valves under the seat too

 

[LD1]

Ok, so one side is P, the other side is T. There isn't a PB. The line other than the 4 going to the front loader lift and curl, is on a third joystick lever going to a quick connect at the rear of the tractor, I guess a one way valve for a rear implement. The thing that's confusing me is how the T line is working. E.g. it must be trying to return fluid to the tank, but the port it's going to appears to be the pressure line into the rear 3PH. I also don't see any blanked holes where a return line might be plumbed in. It's clearly worked like this for many years though, just not had a need for the 3ph I guess.

So let me ask a simple question....is there 6 or 7 hoses going to the front end loader valve?

4 are obviously the loader functions. But asside from that, are there 3 or 2. Because the way you word it is confusing.

You say on one side is P.......yup. makes sense, that is coming from the pump and supplying the loader valve.

On the other side is a T....and you say it appears to feed the 3PH...

You say you dont see a PB port but mention a 3rd hose going to a remote valve.

So this is where we have issue. IF your loader has 3 hoses not counting the 4 functions....then one of them IS a PB hose.
And it sounds like the PB is going to the remote valve and the tank (T) hose is going to the 3PH.

The way a loader valve works is there is ONE inlet but TWO outlets. The PB (power beyond) outlet is for supplying down stream functions under pressure. The T (tank) outlet is a return to tank line for when a loader function is activated. Like lowering the loader....you are supplying fluid to the rod side of the cylinder but the opposite end of the cylinder needs to expel fluid back to tank in order to lower. That goes out the T port. When no loader functions are being activated....pump fluid flows out the PB.

Hence......the 3PH moves when the loader is operated....because you are now sending the cylinders return fluid out the tank port.

For the original owner it was probably never an issue if he never used the 3PH. The 3PH itself is an open center valve.....and using the inlet port of that valve (which is internal to the tractor) was as good as dumping it right to tank.

You have a few options....
1. get rid of the rear remote valve if you dont plan on using it. Hook the hose supplying it to the 3PH inlet where the Tank hose is currently hooked. Then find a new place to return that one to tank.

2. come off the rear remote valve PB port (if it has one) and supply the 3PH with it. Then you need a tank line from both it and the loader valve returning to the tank somewhere.

 

[LD1]

Also, where/how were the backhoe hoses hooked up? Could be that the remote valve was supplying the backhoe. Usually a backhoe loop has to be connected back to itself to feed the 3PH. So that could be something simple to look at too

 

[spikey_mern]

What you just said about the 3PH being open center valve now makes sense.

The backhoe isn't supplied any hydraulics by the tractor. It runs off the PTO and has its own hydraulic tank and pump.

There are 7 lines on the loader valve. I think the seventh one is just connected to one side of the third joystick though. It activates (you hear the pump struggle because nothing is connected to it) when you move the third joystick in one direction. Did some older (this is a late 80s machine) loader valves not have power beyond ports?

Back to that triangular block under the seat - the original part there only has two ports out and back into the tractor

Part numbered 17 there.


That part is different on mine, which must have been changed many years ago to support having the loader on. There is a plugged third port on it too I think, so I'm going to pop it off and have a look at it. Part 10 in the diagram is listed in the parts book as a 'cap, blank' so I'm wondering if that is a return to tank port. I don't see that on mine but it may be where this third plugged port on mine goes to.

 

[LD1]

Usually those block off plat or caps aren't really block off plates.

Its a place to add functions like the loader or a remote valve.

With the original plate on it....it would simply connect the two ports....not block them off. One port would be high pressure oil coming from pump, the other would be return (but not to tank) rather it is return to the 3ph control inlet.

So with no attachments....the 3ph plumbing is mostly internal. So think of that "cap" as a hydraulic hose couples right there that is feeding the 3ph. And changing the "cap" is like uncoupling the 3ph feed, and allowing you to feed something else like your loader first....and then tying the loader back in to feed the 3ph.

It's hard to understand just where all the hoses are going and routes without actually laying eyes on it and tracing the circuits in person.

But it your loader valve indeed has 7 hoses.....you DO have a P (supply);a T and a PB.

The supply is probably coming from that cap. Your loader works fine.

But as I said....you have two ways for oil to exit your loader valve.
1. It exits the PB port when the loader isn't being cycled.
2. It exits the T port when the loader is cycled.

You have the T port going back to the 3ph feed. Which is why it only works when you cycle the loader.

Since the original owner had a backhoe and never used the 3ph....dumping oil back to tank through the open center 3ph valve when using the loader was ok. And he used the PB loader port to go to the remote valve.

I don't think you posted pictures of the remote valve plumbing.

Ideally it will have 3 hoses to connect it. It should have it's supply coming from the PB of the loader....and it shall have its own PB port to feed the 3PH as well as a second tank or return.

The only things that can be TEEd together are the tank lines.

In an open center system you can never tee a P or PB line.

Right now.....if you want to omit that remote valve just to get working....follow the T hose coming off the loader valve and unhook it where it attaches to that "cap". Find a new place to dump it back to the hydraulic/transmission case. And take the hose currently going to the remote valve and put it on that "cap" where you just unhooked the tank line from

 

[npalen]

Might add that the danger in using a T port to feed a P port is that the valve with the T port may not have been designed to withstand system pressure in the housing and could "explode" if downstream pressure is excessive.

That excessive pressure could be caused, in this case, by an unusually heavy load on the 3PH.

 

[chrismac]

Yeh, all still works fine. Backhoe is only connected to frame and PTO, not into the tractor hydraulics. I've been reading @chrismac long post and it looks like he had the same triangular block under the seat. But then it also fed another set of spool valves under the seat too

Hi, I see your having hydraulic issues, the 2 ports on top of your hydraulic block under the seat need to be plumbed in completing a feed loop if that makes sense, you maybe have seen that on my post, this then goes on and feeds the 3 point linkage, the centre port which is currently blocked on your triangular block is for a free flow return to the tank.

https://flic.kr/p/2n8nVAN

hope that works if not I will fix the link later.

Chris

 

[spikey_mern]

Thanks Chris, I was hoping you might chime in seeing your experience with the same tractor!

So the issue I have is the loader valve doesn't appear to have a power beyond valve - just a third joystick valve that goes to a point at the rear

Unfortunately, I don't have a rear spool valve like yours under the seat :-( I doubt I'd be able to find one of them these days but correct me if you know where I might look, especially if you know the part number.

Here's a pic under my seat

So I feel like my options are:

Live without the 3ph (I could at least feed the T port to the right middle hole from the loader)

Somehow source one of those under seat valves

Or, replace the loader valves with one that has power beyond and feed it back to the right place

 

[chrismac]

Thats strange as you would think it would have been working when who ever did it put it together, so with your current set up you are dead heading the pump as there is nowhere for the oil to go? until a leaver is operated, you would know as there will be load on the tractor, any valve with HPCO (high pressure carry over) would do, £100 from flowfit if you need it, same as the replacement I tried for my loader. On the picture above is the front hose going into P in the loader spool, with T on the loader spool going to the rear of the triangular block , that would explain why your arms are working as you mentioned only when the loader is operated as only then is oil flowing through the system, if your loader spool had HPCO that would return to the rear of the tri. block and the return line from the loader spool would feed into the centre port currently blocked dumping oil into the back end.

 

[CADplans]

So I feel like my options are:

Live without the 3ph (I could at least feed the T port to the right middle hole from the loader)

Somehow source one of those under seat valves

Or, replace the loader valves with one that has power beyond and feed it back to the right place

You do not have to live without the three point.

There is a selector valve,, one inlet, two outlets.
Install that valve, select "A" if you want the loader powered, select "B" for the three point.

Not perfect, but, cheap, and easy to install.

 

[LD1]

You keep saying your loader valve dont have power beyond but you have 3 hoses going to your loader valve stack not counting the 4 function hoses.

its confusing because looking at your pictures we cannot see where both ends of a single hose goes and you havent labeled anything.

Take your pictures that you have....and label things and maybe we can help better.

Show the valve and label hoses like 1, 2, 3, etc. Then show the pic of the triangle and under the seat and label then as well so we know for sure what hoses are going where

 

[spikey_mern]

Hey all - thanks so much for all the help you've all been providing so far, and sorry if my explanations haven't been clear enough. I think @chrismac that's what I need to do. I'm guessing the pump or somewhere in that unit under the seat there must be a relief valve - but you're right in your analysis that the pump is currently dead headed, which I've come to realise with this thread and the investigations

@LD1 I've done some annotations, hopefully this helps clear up the 7th pipe from the loader valve, but let me try to explain alongside:

Under seat - with annotations - that one labelled 1 is fed by that 7th pipe from the loader valve, which is only actuated when the third lever is raised

Then the loader valve - just showing the P port on the outside. There's no markings on the case by that port above, I'm assuming this is a relief valve? It has 1700 marked on it:

And the three levers:

And finally the rear of the FEL valve:

And yes, when numbering things I didn't put a number 2 in there by accident!


Cheers

Martin

 

[chrismac]

Well done you have sussed it, I had a guess that would be the way is was piped in, T returning back to the rear of the triangular block, all you need to do now is have a think about your next step, whats the fittings underneath the spool valve for? the ones you can see in the last photo.

Chris

 

[spikey_mern]

Well done you have sussed it, I had a guess that would be the way is was piped in, T returning back to the rear of the triangular block, all you need to do now is have a think about your next step, whats the fittings underneath the spool valve for? the ones you can see in the last photo.

Chris

Do you mean the three on the bottom edge? I think that's where the arms go up and down with the spring inside that actuate the hydraulic fluid to the A and B ports for each set. I am thinking I need to take off the valve so I can actually see it properly and clean it up really well, to make sure I'm not missing a hidden carry over/power beyond port. It's all a bit tight down there - just need to nip back to the guy I bought it from as he forgot to give me the legs to attach to the loader to be able to remove it from the machine. Should give me much better access to look at it once the metalwork is out the way.

Glad I found out about flowfit from yours and a few others posts on here too - prices seem very reasonable. Did you ever sort out the issue with your valve where it would drop rather than raise if you were just feathering it?