Super Dexta Hydraulics

This forum is about the Fordson Dexta, Super Dexta and Petrol Dexta.
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Patveale
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Super Dexta Hydraulics

Post by Patveale »

My problem is the hydraulic arms lifting too far.
The tractor has been in the family for 30 years and the hydraulics worked to a point. They have never worked in draft, I'm not putting up with that..
Off came the top cover, and I tried to set it up as per instructions, but ran out of adjustment on the turnbuckle. I put a small nut inside the tube and managed to adjust both position and draft. On reassembly the draft control appeared to work, it lifted up the arms. However, in both positions it lifts too high. If the arms were connected they would foul in the back axle. I have had the top off 20 times, and tried tweaking everything I can think off. Nothing made any difference to the height the arms lift.I even put in a worn cam stud, but still no difference..
Any suggestions please?
Thanks
Patrick

Hair Bear
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Re: Super Dexta Hydraulics

Post by Hair Bear »

Take on board that I know nothing about the dexta, is it possible the primary lift arms have been removed at some point in it's history and were replaced on the wrong position on the cross shaft? I'm not sure it's even possible but just a thought.
You're supposed to eat greens, not drive 'em!

Billy26F5
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Re: Super Dexta Hydraulics

Post by Billy26F5 »

I think you'll find that's what they do, as there's nothing to stop them doing it (good job fixing the other issues). Rob, both arms are identical on Dexta's and Super Major's, it's only on earlier Major hydraulics that the arms can be the wrong way round. The only thing that stops the lifting is the knock-off pin (on the valve actuating lever), but that's only adjustable on NP Super Major's. check it though just in case.
Sandy
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Patveale
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Re: Super Dexta Hydraulics

Post by Patveale »

Thanks for the idea, I presumed that the arms would have a master spline, as in the T20.
The arms have been replaced at one time as they are for a pick up hitch. Which I presume would have been fitted after sale.
Now all I have to do is see if I can remove one to see.
Many thanks, I'll report back.
Patrick

Patveale
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Re: Super Dexta Hydraulics

Post by Patveale »

As expected, they have a master spline. As they are fitted with the pick up hitch they can't be on the wrong side.
Next idea????
Thanks

Hair Bear
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Re: Super Dexta Hydraulics

Post by Hair Bear »

Beats me. To my mind the movement in the top is 'limited' - the piston can only move so far, the dog bone can only travel so far, which limits the rotation of the cross shaft... etc.
Wait, do the arms go all the way down? If not, is it remotely possible that there is something inside the piston ie something stopping the dog bone seating all the way home? Maybe a PO needed extra lift and put a nut or similar in there to get more height - that would almost certainly upset all the other settings you've been having odds with.
Outside of that, have you measured the length of the drop arms just to confirm they are not from something else and too short?
You're supposed to eat greens, not drive 'em!

ianpdexta
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Re: Super Dexta Hydraulics

Post by ianpdexta »

I would have thought that the upper limit of the arms was controlled by the valve in some way rather than meeting a dead stop. In the same way that they stop half way up or where ever you set the lever to. You don't say whether the arms can be stopped half way? If not then there must be a problem with the valve and / or its linkage mechanism.
Regards
Ian

Billy26F5
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Re: Super Dexta Hydraulics

Post by Billy26F5 »

The top position is governed by the knock-off pin, but that happens to be about the moment the lower links touch the axle castings (with the lifting rods set at a fairly typical length), and is not adjustable. I would check the knock-off pin and set the lifting rods to the length that seems to work best, I can measure Davie tomorrow if needed.
Sandy
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Patveale
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Re: Super Dexta Hydraulics

Post by Patveale »

Thanks for the ideas, but none have helped. Knock off pin is OK, and nothing behind the 'Donkey's Dick' as they call it in Australia, but they would.....
The only way I could get the adjustments on the control valve right was by putting a 2BA nut in the tube in front of the control valve, then I had enough adjustment on the turnbuckle.
However, having done that, position control works OK, but fully lifts the arms in the lower third of the quadrant.
While in draft it will only lift up if the arms are fully down first. If the arms are half way up nothing happens.
And it seems so simple...
Thanks,
Pat

Billy26F5
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Re: Super Dexta Hydraulics

Post by Billy26F5 »

I suggest you recheck the qualitrol linkage, and the main control spring adjustment, see what that does.
Sandy
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Patveale
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Re: Super Dexta Hydraulics

Post by Patveale »

Thanks for all your support, but it now seems to work OK...
Position control works fine, and lifts higher than it has done for ages, so the pick up hitch works again.
In draft when the quadrant is moved to the top it lifts the arms right up, as it should. I haven't a plough to fit it for the ultimate test but all the signs are good.
I did have to put a 2BA nut inside the tube in front of the control valve to get it to adjust properly. Not recommended, but when needs must.. No doubt its a bit worn since it left the factory 60 years ago.
Big thanks to Rodney who lent me the jigs to set it up in the correct position. He doesn't know me, yet lent me these irreplaceable tools. What a good club we have.
Many thanks
Patrick

Hair Bear
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Re: Super Dexta Hydraulics

Post by Hair Bear »

Good to hear.
You're supposed to eat greens, not drive 'em!

Billy26F5
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Re: Super Dexta Hydraulics

Post by Billy26F5 »

Good you've got that fixed. These things sometimes happen but if they work then as long as nothing suffers I don't see why it should be a problem.
Now to enjoy your Super Dexta!
Sandy
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shepp
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Re: Super Dexta Hydraulics

Post by shepp »

I had similar type of issues setting up the cover on a Super Dexta 3000. The problem is that as you get slight wear in the internal components, and as the position control rod bends slightly in use, then setting it up by the book often does not work, and you have to revert to trial and error and slight modifications to the internal apparatus. Under "World Series" on this forum read my posting titled "3000 Hydraulics" and the comments of myself and other people, it might be helpful.
1946 E27N, 1952 Major Diesel, 1959 Power Major, 1962 Dexta, 1962 Super Dexta, 1963 Super Dexta NP, 1964 Super Major NP, 1965 Super Dexta 3000, 1966 Major 4000, 1967 3000 PF, 1994 5640,plus Basildon built NH.

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