David Brown 990 link arm issue. Can ayone help?

[Chrisw]

Hi all,

I have just bought a DB990 to rnu my drier, mainly and to do a bit of beet hoeing. Only problem is the link arms won't go down, well not without unscrewing the plunger behind the quadrant lever. I have already taken that plunger out and apart and cleaned it through, then also the 2 springs and plungers below it too. Everything is free and clear. Put it back together and still same issue. As soon as the lever is pulled even slightly up, the arms start to raise, and will keep going all the way up. putting the lever all the way down stops teh arms raising, but they wont go down. What am I missing? Are there other valves that need to be checked/cleaned??

 

[Chrisw]

Also forgot to say, I have also tried to join the DB forum but it won't let me register, and the contact admin page is disabled!!

Or are there any members in or close to Cornwall who have experience of working on these tractors?

 

[Courier]

Red (Implematic) or White (Selectamatic) ?

 

[Chrisw]

Red (Implematic) or White (Selectamatic) ?

White bonnet red chassis. The book says Selectamatic

 

[Bald n Grumpy]

Have you checked that the selector dial behind the hydraulic lever is in the centre on hieght setting always pull hydraulic lever right back before changing this setting

 

[Chrisw]

Have you checked that the selector dial behind the hydraulic lever is in the centre on hieght setting always pull hydraulic lever right back before changing this setting

Hi,

I have tried it in external mostly, but have moved it to height and to draft, and it makes no difference. I managed to strip it out today and checked all the valves. One on the side, above the large bolt seemed a bit stiff, so freed that up. The only adjusment I did was to a small grub screw on the quadrant lever pressure plate, as it wasn't contacting the plunger under the valve block at all. Managed to get it all back together and check it, and the arms raise, no matter where the lever is, which is worse than before, when I could at least stop them raising, but couldnt drop them. Going to have to strip it all again tomorrow.