Hydraulic spool valve not doing what it should

[chrismac]

After seeing another post about a spool valve, it reminded me of an issue I have,
I have a spool on an iseki tractor, it has a polymark beaver loader and backhoe, the spools on the loader have suffered water ingress so the slider parts are pitted, I have dressed them a little and they are operational but they leak after a while, so bit the bullet and bought a replacement set of spools from flowfit.

See the videos of whats going on, with the new spools fitted the loader actually goes down before it goes up, spools sent back to flowfit and checked for operation, confirmed as good (only thing they never did was replicate the weight of the loader during operation on their test bench)

I have the flowfit spools back but not even taken them out the box (probably 2 years ago now) I still have the old spools fitted. There was lots of discussions of whats going where on my hydraulics but if I switch one out for the other surely that has to confirm the system works one one spool and not the other.

I am left with some old leaky spools and a new set of spools that are no use to me yet. I wonder can the expertise on here help me out.

Old spool (video)
Untitled by chrismac2012, on Flickr


New spool (video)(with power beyond removed here) I would have had another video but cant find it now. but it never changed what was going on.
Untitled by chrismac2012, on Flickr

Anyone got any ideas why its going down before its raising its self?

New spool with power beyond fitted, just a pic.

Untitled by chrismac2012, on Flickr

Picture of old spool

DSC02868 by chrismac2012, on Flickr

 

[m_c]

The spool is allowing the output to leak to return/tank before it's pressurised.

I wonder if they've supplied it with a Negative Overlap spool, instead of a standard spool-

 

[m_c]

Actually, I don't think negative overlap should be an option for a twin valve.
And having had a quick look over the various options, there doesn't appear to be any open centre spool options, but I'm assuming it's a Galtech valve you have.

And I've just realised your valve has three pipes to the tractor.
It could be that the new valve is the entire wrong spec, as I'm going to guess the old valve uses a pressure carry over system.
Do you know where the three pipes to the tractor go?

 

[dieselsamurai]

third pipe is for power beyond ,, shouldnt affect the issue hes having its very odd. Like you say seems to be an overlapping issue for some reason

 

[m_c]

I have seen a worn spool cause the same problem on an old JCB.
Main back actor would drop before it lifted, and we had planned to bodge it by fitting a pilot operated check valve, but the owner got the chance of a newer JCB for a good price, so he sold it.

 

[Rannsachair]

Do you have a part number for the new spool valve?

 

[chrismac]

Thanks for the replies,

Here is the poor drawing I made of what is plumbed in
Untitled by chrismac2012, on Flickr

There is a 2nd spool under the seat as it used to have rear spools but I have not replaced the pipework yet so the spool is all blanked apart from the HPCO or power beyond, to feed the loader spool.

I'll try and get the flowfit spool part number.

 

[chrismac]

2 BANK 1/2" FLOWFIT VALVE 1 150 L/MIN DA VALVE MAX 315BAR (text from invoice)

Cant find the exact but these are close... https://www.flowfitonline.com/categ...-min-double-acting-cylinder-spool-3-positions

 

[chrismac]

Actually, I don't think negative overlap should be an option for a twin valve.
And having had a quick look over the various options, there doesn't appear to be any open centre spool options, but I'm assuming it's a Galtech valve you have.

And I've just realised your valve has three pipes to the tractor.
It could be that the new valve is the entire wrong spec, as I'm going to guess the old valve uses a pressure carry over system.
Do you know where the three pipes to the tractor go?

I actually had the new spool fitted with the 3rd pipe for power beyond too, just not in that video, no difference.

 

[m_c]

I actually had the new spool fitted with the 3rd pipe for power beyond too, just not in that video, no difference.

If you didn't have the power beyond pipe fitted, then what did you have connected to the power beyond port?

If you had it blanked, and the pressure relief valve wasn't continually blowing off, then that would suggest the valve block doesn't have the correct power beyond valve fitted.
However, that shouldn't affect the loader dropping before it lifted, as the valve should be diverting the hydraulic flow before the power beyond section.

 

[Brad93]

Power beyond, as in load sensing?

 

[sako243]

Power beyond, as in load sensing?

For extra functions rather than load sensing. Basically to take the hydraulic flow off to more spool valves.

 

[chrismac]

If you didn't have the power beyond pipe fitted, then what did you have connected to the power beyond port?

If you had it blanked, and the pressure relief valve wasn't continually blowing off, then that would suggest the valve block doesn't have the correct power beyond valve fitted.
However, that shouldn't affect the loader dropping before it lifted, as the valve should be diverting the hydraulic flow before the power beyond section.

This was 2 years ago, I blanked it but cant remember what else I did to get it working, I will have the emails to flowfit as it was them who asked me not to use it as a test.

I have a few emails but unfortunately the pictures attached with the text are not visible.

Here is one reply from me though if its of any use with another issue I came across

Hi, please see the image below, maybe you can help by seeing my routes,

So if I disconnect the HPCO the loader works fine on the raise and lower leaver but nothing happens on the tilt leaver, how on earth can this be happening? Thanks again for your help.

Can you guy think why that would happen out of interest.
Thanks

 

[Rannsachair]

2 BANK 1/2" FLOWFIT VALVE 1 150 L/MIN DA VALVE MAX 315BAR (text from invoice)

Cant find the exact but these are close... https://www.flowfitonline.com/categ...-min-double-acting-cylinder-spool-3-positions

Really need a part number to see what spools are in it or just guessing what is wrong, certainly looks like a wrong spool if works with original valve.

 

[chrismac]

Really need a part number to see what spools are in it or just guessing what is wrong, certainly looks like a wrong spool if works with original valve.

I'll see if I can get it, it will be on the spools in the box I have not opened in disgust.

 

[chrismac]

Does not seem to be much info on the spool, I have taken a pic of top and bottom incase the numbers do mean something,

Untitled by chrismac2012, on Flickr

Untitled by chrismac2012, on Flickr

 

[Rannsachair]

Does not seem to be much info on the spool, I have taken a pic of top and bottom incase the numbers do mean something,

Untitled by chrismac2012, on Flickr

Untitled by chrismac2012, on Flickr

The numbers are the casting numbers, not the part number unfortunately the Part Number is missing, looks like it is this catalogue https://www.flowfitonline.com/uploads/PDFproducts/DCV23.pdf the correct body is shown on page B-42, the fact they have not fitted the nameplate with part number suggests it may be a special to me.

Could try putting an airline to P and seeing where the air comes out as you move the spools, can also check where the return line goes during the same operation.

 

[chrismac]

I'll get this done when I get a chance, I am trying how I piped it up now, just out of interest. I'll get back once I get to it.

 

[m_c]

The numbers are the casting numbers, not the part number unfortunately the Part Number is missing, looks like it is this catalogue https://www.flowfitonline.com/uploads/PDFproducts/DCV23.pdf the correct body is shown on page B-42, the fact they have not fitted the nameplate with part number suggests it may be a special to me.

Could try putting an airline to P and seeing where the air comes out as you move the spools, can also check where the return line goes during the same operation.

It probably never had a part number plate on it.
From my understanding of these, FlowFit probably buy a stock of individual parts, and assemble as required.
If you were to strip the spools out of it, you might find that they have a type number on them, but I can't see any options in the catalogue that would deliberately cause the problem.

However, that block doesn't appear to have a carryover adapter fitted, as it should be quite noticeable -

But that shouldn't cause the problem anyway. It would only cause the hydraulics downstream to get no pressure.

If you refit it, I'd try swapping the functions around, and see if the problem exists with the main up/down on the other spool.
You could also try reversing the A/B to see if the problem exists in the opposite direction.

 

[chrismac]

It probably never had a part number plate on it.
From my understanding of these, FlowFit probably buy a stock of individual parts, and assemble as required.
If you were to strip the spools out of it, you might find that they have a type number on them, but I can't see any options in the catalogue that would deliberately cause the problem.

However, that block doesn't appear to have a carryover adapter fitted, as it should be quite noticeable -
View attachment 482287
But that shouldn't cause the problem anyway. It would only cause the hydraulics downstream to get no pressure.

If you refit it, I'd try swapping the functions around, and see if the problem exists with the main up/down on the other spool.
You could also try reversing the A/B to see if the problem exists in the opposite direction.

Your correct, I have the carry over adaptor in a drawer.
I'll put some air on it first, just as clean option to start with and report back.