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.