1960 950 Hydraulics - Drifting up

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Will-l125
Posts: 3
Joined: Sat Mar 16, 2019 2:36 pm
Location: Gloucestershire

1960 950 Hydraulics - Drifting up

Post by Will-l125 » Mon May 13, 2019 9:10 pm

Sorry if I have missed a similar thread to this in the past but I have an issue with the hydraulics on a 1960 950. The three point linkage kept drifting back up and wouldn't stay down.

I started unpacking a few bits hoping to find some adjustment or easy access valves to clean up but haven't had any luck yet... the control box is on the front of the rear axle on the right hand side, I have had a look inside and cant see anything wrong. I have also had a look in from the rear inspection panel but can see how to remove the valve? there is a cir-clip there but not sure how to remove the valve? (if possible)

Any ideas out there if I have missed something or if I need to go a little further? Hopefully the photos help to explain and describe the tractor better...
- First photo is through rear inspection panel of the axle
- Second photo is of the control box on the front of the rear axle

Any advice appreciated

Thanks
Attachments
img_20190316_140950__mSSGp.jpg
inspection panel looking in from the back of axle
img_20190316_140950__mSSGp.jpg (91.18 KiB) Viewed 408 times
img_20190316_141041__PciC1.jpg
looking at the control box on the rear axle from the front
img_20190316_141041__PciC1.jpg (88.03 KiB) Viewed 408 times

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db2d
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Location: Monmouthshire

Re: 1960 950 Hydraulics - Drifting up

Post by db2d » Mon May 13, 2019 9:43 pm

Briefly— I suspect the problem is the friction discs on the control levers. If the control lever is loose there are three possibilities 1.The discs need adjustment. 2. The discs are worn out 3. The mills pin has sheared in the lever inside the control box.
The valve unit pictured is not the cause of the problem but the whole system will have to be correctly adjusted.

Will-l125
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Joined: Sat Mar 16, 2019 2:36 pm
Location: Gloucestershire

Re: 1960 950 Hydraulics - Drifting up

Post by Will-l125 » Mon May 13, 2019 10:22 pm

Thanks for the response,

Is that all accessible by taking off the front plate of the control box? I had a look in there before but couldn't see anything alarming. May have a closer look if you suspect that to be the issue.

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db2d
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Location: Monmouthshire

Re: 1960 950 Hydraulics - Drifting up

Post by db2d » Mon May 13, 2019 11:03 pm

If the control lever will not stay in a set position it has to be the options I stated.

blissakpo
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Location: IRAQ

Re: 1960 950 Hydraulics - Drifting up

Post by blissakpo » Tue May 14, 2019 11:25 am

Grab the control handle and wiggle it – If it is tight with no lateral movement then replace the friction discs.

Search this forum for Haynes Manual and follow the link

There you will find a DB 950 Parts Manual that gives an exploded view. You can do it on the tractor and do not need to take off the front plate.

The friction discs sit behind the control lever. Undo the nut on the end of the shaft in your picture 2 and pull off the shaft (Careful with the woodruff key ) replace the friction discs as required. (They are available from David Brown Parts).

The shaft (Part 14) is metal to metal on the control box casting (Part 44) the shaft can wear resulting in a sloppy movement of the control lever. This will also give the same results as worn friction discs (With the engine running vibration makes the control lever rise) Replacement shafts are available from Barclay Williams. To do this you do need to take the whole assembly off the tractor. First disconnect the hand brake, then remove the front cover, then remove the bolts inside (you have to remove pin Part 22 to swing the rocker lever out of the way to get at one of them.

Then from the back of the tractor undo the nut with the spring behind it in your photo one and undo the big bolt (under the spring in your photo – This is a banjo bolt be careful not to drop it or the sealing washers into the axle) two man job to have a hand in there catching the washers as the whole assembly is pulled out from the front

The whole system works by the control lever acting on a plunger (Part 6) there should be a spring and a circlip on the outside obscured by the nut and slotted screw thread above the handwheel in photo 1. The plunger acts on a cam in the axle. It is not uncommon for the circlip to ping off. The lift arms will then raise but not lower. People assume the spring is on the inside and try to free it with a tap from a hammer – so the plunger overrides the cam. The end of the plunger that acts on the cam should be pointed and as the control lever is operated the plunger rotates slightly reducing wear but after 58 years of use you will probably find it has ceased rotating and the end has adopted the same profile as the cam it acts on. Plungers and Inserts (Bush) assemblies are also available from Barclay Williams – If you have to strip the unit off the tractor I would suggest that is replaced at the same time as it’s a ************ nuisance to have to strip the whole assembly to do such a simple fix.

New gaskets are also available from David brown Parts.

Replacement friction discs are not the same thickness as the originals (thicker) you may need only two instead of three shown – It is important that the grub screw (Part 3) on the end of the control lever hits the plunger ( Part 6) square on or you will find the circlip and spring ping off regularly and to fix it you need to do all of the above over again. Eventually I modified my plunger by drilling a hole through the end and replacing the circlip with a washer and split pin which seems to provide a much better solution to the original.

But on the bright side you get very proficient at stripping the system

Hope that helps

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ollek
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Re: 1960 950 Hydraulics - Drifting up

Post by ollek » Tue May 14, 2019 11:33 am

The following is a link to the official Case UH parts list, showing the hydraulic lever arrangement, for David Brown 950 Implematic. https://partstore.caseih.com/us/parts-s ... 65ar702080

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db2d
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Location: Monmouthshire

Re: 1960 950 Hydraulics - Drifting up

Post by db2d » Tue May 14, 2019 1:52 pm

I am not going to get involved in an argument but the method described for replacing the friction discs is definitely not the correct method.

Will-l125
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Joined: Sat Mar 16, 2019 2:36 pm
Location: Gloucestershire

Re: 1960 950 Hydraulics - Drifting up

Post by Will-l125 » Tue May 14, 2019 8:50 pm

Thanks for the advice all!

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