hydraulic control valve

[tom lad]

hi


how do i test my main control valve -- i.e make a decision wether i need a new one ......
arms are dropping leaking somewear i believe ..

also who supplys new ones ??

thanx

[Brian]

It is highly unlikely that your control valve would cause a problem. If someone has cleaned it with wet and dry or emory cloth then you may have problems.

It is not just a case of fitting a valve, the clearances measured around the valve as it fits in the bush are measured in microns or thousandths of a millimeter. You normally go by the colour code on the bush and fit a valve with the same code, but that is the theory. In fact you have to have a number of different colour codes and find which fits in the bush best.

The fit is determined by allowing a lubricated valve to just fall slowly through the bush under its own weight.

You will need special pullers to pull and replace the control valve bush and the correct spacer to determine the position of the new bush in the cylinder.

I would make sure that my leak is definitely coming from the valve. If a control valve is worn the normal problem is sticking in the bush.

[tom lad]

now im really confused lol

id convinced myself that spendin £30 would mend my bobbing link arms ...

i haven't pollished the valve ect. so i guess its best left alone. as i've said in my other post it feals a nice fit but can u tell with my big fingers ... no signs of binding at all so im gonna leave it alone .

wen i ran her the other day it is correcting constantly ,only a few inchs but its annoying every few seconds ,

raise an implement ,pull out the aux knob switch off and hold up a 3 f plough all night not move a inch. new lip seal working me tinks . if u push in the knob ,very machanical clunk wen it takes up the play ?

as far as i know i've changed all the o ring and i honestly no idea whats wrong ,
the cap / guide / bush at one end of the unloading valve (the tapped round one , same end as spring for the control valve i think ) is only a nice fit - the manual makes it sound lke it should need a puller .. but it drops out quite easlly ... should it be oil tight ? its held in by the plate , two set screws .

thanx again brian

[Brian]

The unload valve plug should be oil tight and a tight fit in the cylinder. If it is not, this could be the cause of your leak. The largest you can get is "red-white". Try an old Ford dealer. I do not know if Agriline do one.

The plate and screws only hold the control valve spring, not the unload valve plug, that should be driven in fairly hard.

[tom lad]

ok m8 i'll look in to this


thank you

[tom lad]

my plug IS loose !

i can feel slight side slap when its in place , with a bolt screwed in .

would deffinatley drop out with out the plate on - two set screw .

now i notice it i can see wear marks from it rattlin round und round , polish marks u know ?

prob only 1/2 a mm gap but now way oil tight ! i hope this is my leak

so ... how do i fix it .. some sort of a liquid bearing fix epoxy ? but are they oil proof ?

no idea on its size so don't no were to start to try and replace it .
any ideas ?


thanx again brian

[Brian]

Get a Red/White plug from either Agriline or New Holland dealer, you are looking at oil under pressure and I doubt any epoxy will hold.

[tom lad]

hi all

took ages to find the site again lol

having difficulty to get new / another plug
hoggarths my local new holland dealer not replying to me agriline dont do the plug any one any suggestions plz ....



thanx should i be off to an engineer ???? to have it made ...

tractor in bit too long now need a solution sob ..

[tom lad]

update
still bobs same as ever

gets worse as the oil heats up .

had a new unloading valve plug made , the enginer told me the hole / bore was not round / true anymore so he took a few thou out and ground a new plug to sute .
thats about a year ago and i've been putting up with the bobbing.

im now wondering about the flow speed controler on the aux chest , if that spool / valve ( the one that rotates as u screw the adjuster ) was loose worn , damaged could that be my prob?

i had grate difficulty removing the pin that holds the cap top on years ago and its a tight odd fit to remove the valve , i think its slightly bent.
it feels loose if u wobble it but thats prob between the cap and the valve , not the valve and the bore but were talking thous aint we
could my oil be leeking around that internaly ??
so is it easyest to test it by swapping it for a different one , do i risk buying one of a scrapper and hope it better than mine ?
i dont know of a local dexta to borrow one to test , as the bob / correction is obvious i would know within 1 minute if its made a difference.
open to suggestion plz gentelmen ??

[Trevorthetractor]

Hi have you tried Emmarrk? they are in Pudsey nr Leeds West Yorkshire

http://www.emmarkuk.co.uk/home.cfm

[tom lad]

i'll have a look m8 thanx .

[tom lad]

still bobbin only prob worse

think I will have to risk a replacement cover , to test mine ??

to much of a leak / bob to ignore now , it embarrassing .

pull out the knob and she'll stop up perfectly .

[Brian]

Have you looked at the check valve? Its right at the front of the lift cover near the flange of the rear axle and the gearbox behind a screw in plug. You should be able to get it out without taking the lift off. Check for grooves in the ball or a broken spring.

You have isolated the problem to the control valve, unload valve or linkage. I seem to remember you modified the linkage to get the adjustments, so it could be a manifestation of your original problem.

[tom lad]

hi brian
the check valve , ball spring and seat have all been out year or so ago
new ball , the old had minor groves
spring ok I think ?
I removed the check valve seat , renewed a o ring from memory , u told me not to remove the seat but I'd already done it and wished I had n't
it was a tight fit to replace , quite possible I damaged the seat , but the fault hadn't altered either way , so I try to ignore that possibility.
can the ball drop down if I do it in situ?

don't really want to remove the cover again , might be able to see the seat with out removing the whole cover ??
but I will remove if it mends it.

there is now a minor external leak on the flow control shaft , not enough oil for the fault but it shows wear on the shaft ?? as far as I know all the o rings are new / changed by me.

the fault gets worse / quicker after a few minutes , as the oil warms up I presume, still drops with engine off .

what might be wrong with linkage ?

[Brian]

If the lift holds up without dropping when you pull out the ASV then you have isolated everything on the ram cylinder except the control valve, unload valve, check valve and linkage. So your fault must be in what is left. You may have a problem in the ASV, I have known the valve to wear and do strange things but they are usually related to lifting.

Your linkage could be bent and could be sticking causing the valve to move erratically. I seem to remember you could not get the settings without modifyuing the linkage, that tells me there is something badly wrong with the set up. The Position Control cam may be worn, the pin may be worn, the arm itself could be bent, the draft control linkage could be bent. It would not need to be a bad bend, sometimes the only way to see it was to put a suspect one and a new one side by side.

A simple thing might be a faulty "O" ring on the ram cylinder but I don't think so.

There were special tools to remove and replace the check valve seat and, yes, it is very tight. Are you sure you got it back fully? A faulty check valve/seat would give you exactly what you are getting.

Have you taken the PTO selector off and looked inside when the lift is working to see any leak?

Another thing comes to mind, what have you got on the arms when the corrections occur? Or is it anything? Is the top link spring correctly adjuste?

[tom lad]

lots of home work there sir

didn't realise I could see inside thru the pto selector .


I replaced the cfp , it was about half worn thru , so the cam may be worn too. the cross shaft seized .
I had to lengthen the turn buckle to get the setting 1 mm longer I think . so I think worn cam would make sense ?
keep u posted , look into it further when I can , thanx again for the help,

[tom lad]

finally filmed it
cold oil , only light weight in link box

I do think now I've studied it , that at full lift it is blowing off , but lower a bit on the quadrant and it bobs , lever up qualitrol
in draft prob blowing off
not noticed this b4 .
separate prob tho .

http://youtu.be/k1iKpIRDtkI

link to u tube I think

[tom lad]

took the check valve ball out , seems perfect , can see the seat, looks fine not decided yet . new 11mm ball a few years ago
the seat poss. has a mark on one side very minor - how much damage are we talking ?
not to worried about removing the check valve seat ,its replacing it that bothers me , not removed it yet.

with a implement raised the big external control spring can be rotated ,just prob 1 mm /2 mm then tight when arms lowered .that's correct aint it ?

would the flow restrictor spool/shaft being worn cause this fault ? the bore in the aux chest is scratched ,

[Brian]

The spring should be set with the lift arms fully lowered, draft control selected and the quadrant lever lowered. The turnbuckle should then be adjusted so the spring is just held, with no end float.

Your scratched bore could be the problem, any chance of another ASC to try? Pity you do not live closer as I have a good one here.

[tom lad]

definitely play in the flow control shaft , will a ASC of any dexta fit my S dexta for a quick swap / test ?

all back together , trying to see thru the pto lever next .

[Brian]

Super Major, Dexta or Super Dexta, all will fit. Very early Dextas had one less the flow control but that would work too.

[tom lad]

with a 2 f fergie plough hitched +raised oil is leaking in side , top front pto lever side , under the ASC I guess and running along the lift cylinder casting .

quadrant lowered the flow lessens , but raise arms it increases

only very odd drip from the lift cylinder , cant see a leak from the control valve , but vision in there aint good.

next plan is to swap the ASC . as soon as I find another one .

the oil is clean , by me , and quite thick , which I think will be helping things ? bound to be worse with a thinner oil ?

[tom lad]

finally sourced a auxiliary valve chest , ' seems ' to be in good order .

happily swapped them over to test , and guess what , it still bobs .


seems unlikely that they are both faulty ??

don't know what to do
as I see it , its the

check valve seat

the control valve its self
or??

open to sugestions sirs
when transporting a implement that's a bit heavy , but basically a empty link box ,the corrections on the lift cause the tractor to twitch /pulse which is horrible

[oldcharlie]

My super dextra dose the same thing don't have a clue as to what causes it.

[tom lad]

I hardly dare ask the question but how many o rings between the ASC and the lift cover , the new Holland online shows 1 large 7 small if I'm reading it correct .

both my ASC have recess for 1 large 6 small ????????????
I've only ever fitted 7 total

red dots were I've had o rings , arrow is were the online catalogue SEEMS to show extra one ??