NH 7635 Dual Command Issue (also slow loader)

monkspill

Member
Thanks for this, there is flow in the return when the loader is being used up or down but when stationery but the spool for the loader is engaged, this is when there is no flow coming back through the return pipe to the backend. Are you saying there should be flow constantly? This is what I thought should happen same as with an excavator etc, there should be constant flow and then the valve diverts to force the flow and pump to work. On the road recently when I engaged the spool and lifted the loader it wanted to keep rising and went stiff..
 

Half Pipe

Member
Thanks for this, there is flow in the return when the loader is being used up or down but when stationery but the spool for the loader is engaged, this is when there is no flow coming back through the return pipe to the backend. Are you saying there should be flow constantly? This is what I thought should happen same as with an excavator etc, there should be constant flow and then the valve diverts to force the flow and pump to work. On the road recently when I engaged the spool and lifted the loader it wanted to keep rising and went stiff..

Yes, as you say should be flow all the time unless it's a load sensing loader valve block, but it would not work thru a spool valve!!!
Way it is just now will cause lots of heat very quickly at high revs (roadwork) this will cause damage along with draining fair bit hp and burning extra fuel etc etc.
I think it needs look at asap.
Can you check pressure pipe from spool is definitely going to p port on loader valve and return is from t port
 

monkspill

Member
Please see attached pictures,

Also there is another thread I’ve been reading here https://thefarmingforum.co.uk/index.php?threads/trima-loader-hydraulics-plumbed-into-nh-tla.76820/ where they seem to have had a similar issue.

Please see these pictures of the valve block, the left hand Allen key has been noticeably tampered with at some stage, does the LS mean it’s a load sensing valve block which isn’t suitable for my open centre tractor? Why is there a Tee valve on the a1 circuit ?

Thanks again
 

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monkspill

Member
More pictures
 

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monkspill

Member
the loader is also plumbed and wired for electric third service but the joystick doesn’t have any buttons so someone must have pinched it as some stage..
 

Half Pipe

Member
It's possible the loader valve can be configured for load sensing or not, but I'm not familiar with that valve.
If your good with Google etc you may be lucky and find a manual for the valve.
Other option is a new valve, joystick etc
Needs to be 1/2" ports
Something like this
https://www.tractorparts.co.uk/Trac...r-Crow-Tilt-with-Single-Level-for-3rd-Service
You will not need a diverter valve if one on loader is ok.
Some valves on eBay also, but if going down new valve route best to get some advice
 

The Man

Member
Location
Cavan
It’s a load sensing valve chest all right that someone’s rigged up to work on that tractor their should be a port on the right hand side that you can put a third return pipe and run it into the back of the tractor might help it out a bit a decent 5/8ths return. The way it’s plumbed into a spool isn’t ideal but should work all the same just make sure not to leave it pumping when your driving down the road not using the loader. As for your sticky spool valve I’d say your cables are seized. If their like the bigger Tm’s theirs an aluminum housing behind each spool comes off with a 10mm spammer then a little pin disconnects your cable if the lever in the cab is still stiff it’s your cable if it’s free to move the problem is with your slice.
 

monkspill

Member
Thanks for this, I cant see a port on the right hand side I can see the LS symbol on the bottom of the block however. If you look at the picture there’s also 2 things on the top of the valve block, could one of these be teed off as a return? Thanks
 

monkspill

Member
Chaps I’ve had a look this evening, took both caps off and realised they part of the block & float detent etc. I did note that when I had removed the main boom valve cover that if I sent the joystick forwar enough (not enough to lower the loader) with the cover off then the pressure was relieve and must have been flowing through the return.

Looking at what the last poster said it appears there is an L/S port which would be around 5/8 of an inch on the bottom of the block which I’m assuming I can tap into and send into the backend as a return along with the usual free flow return. Any comments on this?? You can see it in the bottom of the block. Thanks again
 

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The Man

Member
Location
Cavan
You can’t use the LS port as a return most blocks have a port on the side for an extra return look at the picture. If yours doesn’t then the only suggestion I have is to run a big 3/4 pipe as your return plunged into the back end the last photo should help it if your only returning using the spool at the minute. Theirs no reason your block shouldn’t work this way after that I’d be looking at the spool valve maybe plug out the loader and try to use that spool to tip a trailer or something to see if it’s slow to tip it or not.
 

monkspill

Member
Thanks for that, what tractor is this off please? The block is very similar to that, the outlet is already 3/4 at least for the return. The issue is when the loader is stationery there is no flow going back to the return and it’s bringing the engine down
 

Half Pipe

Member
Who ever fitted loader valve block has bodged it, mayb thinking it do to shift occasional bale at a stables, but if it has been left with pressure coming from rear spool but only lets it back to the tractor when operating loader and gone for a road trip it will have cooked the rear spool block, most likely causing it to be sticky etc.

The loader valve is either designed for LS line to signal for oil as required ( some load sensing valve blocks can be adjusted for non LS)
Or less likely it could be designed for 3 pipe system where it would take pressure from after trailer brake valve, thru loader valve then carried on under pressure back to rear valve to complete pressure circuit and free flow return for when dropping loader etc.
This setup would give oil priority to brake valve, loader then rear hydraulics,
This is how the loader works on thread you linked to in post #42
But that tractor has the classic valve block!

You have the deluxe valves (adjustable flow) and they are different setup, I'm fairly sure when fitting a loader they got a valve (possible a priority valve) put in just after trailer brake valve that used the loader valve LS line to divert oil flow to loader as required! (our 7635 deluxe + quicke loader was plumbed like that) that could be the reason you have a loader valve with LS port but the valve has never been fitted
 

monkspill

Member
Who ever fitted loader valve block has bodged it, mayb thinking it do to shift occasional bale at a stables, but if it has been left with pressure coming from rear spool but only lets it back to the tractor when operating loader and gone for a road trip it will have cooked the rear spool block, most likely causing it to be sticky etc.

The loader valve is either designed for LS line to signal for oil as required ( some load sensing valve blocks can be adjusted for non LS)
Or less likely it could be designed for 3 pipe system where it would take pressure from after trailer brake valve, thru loader valve then carried on under pressure back to rear valve to complete pressure circuit and free flow return for when dropping loader etc.
This setup would give oil priority to brake valve, loader then rear hydraulics,
This is how the loader works on thread you linked to in post #42
But that tractor has the classic valve block!

You have the deluxe valves (adjustable flow) and they are different setup, I'm fairly sure when fitting a loader they got a valve (possible a priority valve) put in just after trailer brake valve that used the loader valve LS line to divert oil flow to loader as required! (our 7635 deluxe + quicke loader was plumbed like that) that could be the reason you have a loader valve with LS port but the valve has never been fitted
Thanks for the replies.

It doesn’t appear to be plumbed in anywhere other than directly to the rear remote & then the free flow return coming back through the top of the back end. One thing I will say is one of the adjustable flow cables is broken and stuck in the “slow” position on the back of the spool block, I’m wondering if this would have any effect?. Would one be for flow & one for return? Thanks again chaps.

Also, are you saying there is a way to make this work or alternatively can you suggest a new spool block/chest that will also allow me to keep my electric third service?
 

monkspill

Member
Also looking at this tractor for sale nh7635 the loader block can be seen with 3 pipes on the bottom of the valve block. I suppose I could take the LS line off and see if the pressure is released/not straining the pump and free flowing when the loader is engaged but not being used
 

Half Pipe

Member
The 2 flow controls are for the 2 rear spool valves you have and would have no effect off stopping return flow from current loader valve.
You could try removing the ls plug and see what happens, you not much to loose.
It's only designed to signal requirement for oil though, so doubt if it's designed for much flow. But I have never tried that.

If you want to use current valve, then best asking someone local with experience of the 35 series setup, the TL range onwards used different setup.

Other option is fit a valve like
https://rover.ebay.com/rover/0/0/0?mpre=https://www.ebay.co.uk/ulk/itm/223533655913
If link doesn't work it's item number 223533655913

It looks like a valve that would work plumbed the way yours is just now and has a button in joystick to power your current 3rd service diverter valve.
But before you buy any valve, speak to the supplier and get them to confirm it will work powered from a rear spool.
That would make it fairly straight forward DIY swap of your current valve
 

Half Pipe

Member
Just had another look at the valve in link above, downside to it is the side exit ports going to loader, not as tidy as top exit ports on your current valve, but gives you an idea of what's available.
Spend some time googling and you may even find plumbing diagram for your current valve.
 

Half Pipe

Member
@monkspill have you had any luck with loader valve?
I had bit of time to study a 7635 with loader joystick.
Even tho it is a fixed displacement oil pump, the rear valve (single block double spool, not slices) is designed for load sensing, there is a valve that dumps pump flow back to transmission when no oil required, it is controlled via a small steel load sense line from rear spool, if you wish to plumb your current loader valve in correctly, it also needs to connect to this load sensing line via a shuttle valve, so either loader or rear valve can request oil. The loader valve just gets t'eed into pressure and return lines between rear valve and the flow control valve
IMG_20190722_140704.jpg

That's best picture I can get of the flow control valve, it's just in front of rear spool block the t piece is the return line

IMG_20190722_140658.jpg

Same valve, from different angle showing shuttle valve, silver square at top.

IMG_20190722_140709.jpg

This picture shows where the loader pressure line is connected to rear block

Shuttle valve not expensive
Reckon it be a wheel off job to get at pipework.
 

monkspill

Member
thanks very much for this chaos I’m sorry I haven’t seen this I haven’t had the email notifications I usually get for some reason. So what would you suggest is the best port of call then?
 

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