Problem with the hydraulic

[Tertho]

Hello, i bought a Dexta from 1958, for about 8years now. I have done a lot with it, change the engine, new complete Head last year. But i have tried to fix the hydraulics many times. I have taken the Hydraulic cover out 4times now, and i just cant figure it out how to repair it.
The problem is the lifting hight, and the arms are dropping when i use the tractor, and when i shut it down, it will take just a minute to drop to the ground.
I have change the piston seal, but did not make any different.

And last time i had the cover off, i tried to adjust the lifting hight, but now the are lifting all the way up, but when i lower the arms just a littlebit, they drop down to about half the lifting hight, i have no controll of the arms.

What should i do?
I am gonna take the cover off againt next week, and take some picture

Sorry for the bad english, i am from Norway.

[mathias1]

Terto,

Welcome.
You will have to look deeper into your hydraulic system. If the arms are dropping that fast, you will have a leak somewhere or a valve that's not working correctly.
The places you definitely need to check are:
- plug in front of the unloading valve
- the unloading valve itself
- control valve

Did you do a test on the hydraulic pump?

your lift may also be out of adjustment.
The details for the adjusment can be found in the wiki, they are as follow:

Super Major (up to 1963) and Dexta / Super Dexta lift settings.

The hydraulic lift is very heavy and awkward. Proper lifting equipment should be used to lift this from the tractor.

Remove hydraulic lift from the tractor and place on workbench with ram cylinder upwards. A trumpet shaped guide is fitted to the control valve on the Super Major and a metal tube on the Dexta. Check that this is undamaged. Any damage may indicate that this area has been hit or bent by the lift being dropped or laid on the valve and this may cause sticking problems.

Qualitrol (Draft) Control adjustment. This must be done before Position Control Adjustment.

Move the lift arms to the fully up position. (As the lift is on its back this will mean that the arms are fully down). Now move the arms down until the upper surface of the yoke in which the linkage fits is level with the gasket surface of the lift housing. This can be checked with a straight edge. The arms can be held in this position by tightening the arm retaining studs. Do not forget to slacken these when the lift is replaced.

Set the draft/position control selector into “Qualitrol” (draft).

Set the main lift control lever to the upper raise stop in the quadrant then move it towards the lower position until the upper edge of the lever is 13mm (1/2”) from the top stop.

Adjust the turnbuckle on the control valve until the front edge of the control valve is 10mm from the rear face of the control valve bush in the ram cylinder.

Tighten the turnbuckle lock nut and recheck the measurement.

Position Control Adjustment.

Lift arms in the same position as with the Qualitrol adjustment.

Set the draft/position control selector to Position Control.

Set the main control lever to the lower stop at the bottom of the quadrant.

Identify the position control rod. This will be pushing on a flat area on the control valve operating lever.

Slacken the locknut on the position control rod and turn the rod until a measurement of 13mm is found between the front edge of the control valve and the rear face of the control valve bush.

Tighten position control rod locknut.

Refit lift with new gaskets and “O” rings and having care not to rest the lift on the control valve when refitting it.

Slacken off lift arm retaining studs until arms move freely then refit lock tab.

[Tertho]

Hello again, are now trying to fix the problem.
I cant adjust the turnbuckle 10mm. There is no more threads on the turnbuckle. I can only get 11mm.
When adjusting position control i get 13mm. Had the same problem last time i tried to fix it. I put two nuts in the turnbucle to get measurment to 10mm, but i don't think it work.

I have taken out the control valve, it looks good.
I change the Oring on the unloading valve, it was hard as plastic.

How do i add pictures in the post?
Thanks for answer.

[mathias1]

You are in draft position with the arms at the right place?

[Tertho]

Yes i am. I have been followed the steps in the dvd from Tractormec. But cant get the right measurement

[mathias1]

Pictures you can upload using postimage.org

[Tertho]

https://postimg.cc/HVH0hTX3
https://postimg.cc/QHkm8FhR
https://postimg.cc/8j41hbTw

[mathias1]

Is the main control spring alright? There should be a slight pre load on it. It should be possible to turn it with one hand. Maybe someone has messed it up, when trying to fix the hydraulics.
About the o-ring: you better leave it without fitting it.

[Tertho]

Yes i think the problem is the main control spring.
When i took the cover off there was a 5mm shims between the spring and the yoke. I cant adjust the spring, it has bad threads. I took the 5mm shims off, and put a 2,8mm shims between. Now i can turn the spring with one hand.
I also took the control lever off, and i can see someone have grind a new keyway in it, i took it back to the original keyway.

[Tertho]

In front of the cover there is a valve, should i take it out?
I do not now waht kind of valve it is or waht it does.

[MikesDexta]

In order to display images on the forum go to Postimage picture you wish to display and click on the 'share' button (top left) then highlight the link in 'Thumbnail for forums' box, then right click then copy and finally paste it into your post and it will appear like so:



Seems like you're making progress with the hydraulics so good luck with it

Mike