DB1200 hydraulic valve

[dieselherb]

This tractor has been sitting for years. 3 point hydraulic will lift with engine running, can't make it go down. I took the caps off and springs out of hydrant valve but can'tget the spool valves out. Thought pressure would pop them out, not. How to get them out?

 

[Bret4207]

I suggest starting with the operators manual. Some of the DB's of that era had a locking mechanism to keep the arms up. Usually a problem with the valves will result in the arms not raising at all.

You manual should be the 3rd one down this list- https://sites.google.com/site/deerebrown/

 

[dieselherb]

But the arms can not be lowered at all. Controls don't work

 

[Bret4207]

I don't know the 1200 like I do the 990. RG Martin should be along to help you.

Did you look to see if there is a lock for the 3 pt arms?

 

[dieselherb]

(reply to post at 08:20:28 12/06/20) [/qu


Yea no lock. I have a 990 also. I know how that works not the same

 

[dieselherb]

(reply to post at 08:20:28 12/06/20) [/qu


Yea no lock. I have a 990 also. I know how that works not the same

 

[joestewart]

Watch this video:

https://www.youtube.com/watch?v=LE_dkHea4dM
Removing stuck David Brown valves

 

[dieselherb]

Ok I tried what he did, but mind has threaded brass plug with a tiny hole in it on the passenger side of the unit. Bore looks larger on mine. I started the engine with the plug out, it leaked oil but arms did not go up. But still the control lever does nothing

 

[joestewart]

Herb,

A couple of questions:

Did you remove the brass plug and then screw a bolt into that valve (like the guy in the video)? Then did you use the bolt to pull the stuck valve out?

When the valve was stuck on my 990, I used a slide hammer attached to the bolt to pull the valve out.

That trick will not work on the valve that is on the driver's side (there are no threads in that one). The guy in the video used an expanding concrete anchor to remove it.

One more question: When you pull your "control lever" all the way toward the back of the tractor, and hold it against the spring, do you hear the hydraulic pump straining?

 

[dieselherb]

No I haven't tried to pull them out after I saw the brass plug. I will try today. Don't have a concrete anchor

 

[dieselherb]

Ok so I got 1 valve out. Doesn't look anything like the 1 on YouTube. This 1 is a tube tapered on one end with a tiny screen inside. Don't know if this is supposed to move feely in the bore(it doesn't) And down below that there is another tiny screw( I don't know if I should pull that too) Couldn't get the 2nd valve out, concrete anchor bolt too large, it's less than 3/8.

 

[RGMartin]

A tapered wooden dowel driven in will sometimes free them. I have also used a 7/16-20 taper tap, it doesn't really cut the valve, but will grab it and get it moving enough to pull.

I have also had valves that required beating out from the bottom after removing the valve.

Those valves should slide freely.

 

[dieselherb]

I have what is threaded out. It is a tube tapered at one end with a tiny screen inside the tube. Is that the valve? Don t understand how that works, or how it can move feely? There is a screw below that tube, afraid to take it out( may drop down inside) Or do I need to take it out?

 

[RGMartin]

(quoted from post at 13:51:52 12/12/20)
IIs that the valve?

Sounds like it, hard to say for sure without a picture. The one beside it is very similar.

Think of them as check valves, springs hold them down, hydraulic pressure opens them under certain conditions.


you can polish them by chucking in a drill and using some 320 - 600 grit paper to polish them.

 

[Bret4207]

Yes, they should move freely. Do as Rich said and polish it/them. I'd look at the exploded parts diagram and make sure all the pieces are there. If it's like the 990 there's a little ball that is supposed to sit in there somewhere. Lost mine years ago and the system still works, so not sure how critical it is.

 

[dieselherb]

Going to Home Depot today. Need a anchor bolt smaller than 3/8 to get the other valve out. Which valve controls the up movement of the arms?

 

[dieselherb]

Ok I got the one valve moving great. Still can't get the smaller one out(tried a 5/16 anchor bolt just pulls out , no valve attached) I can get the arms to move up and down but with opposite position of control lever( up is down down is up) also sometimes the arms won't move, if I pull the external hose valve it will shock the arms to move

 

[joestewart]

I had the same problem with that 5/16" anchor pulling out. To solve the problem, I cut an aluminum can into a small strip and wrapped it around the anchor once to act as a spacer and increase the effective diameter of the expansile part of the anchor. That was good enough to get a hold onto the valve. I then used a pair of vice grips to grip the anchor. Then I attached a pair of vice grips to a slide hammer => out came the valve.

 

[dieselherb]

(reply to post at 06:48:02 12/13/20)

 

[Bret4207]

RG Martin can tell you for sure, but I thought the normally problematic valve, the one that controls the up/down on the 3pt, had a 3/8" fine thread interior. That's on a 990, but I believed the 1200 was the same from what I'd read.

Rich? Are you seeing this? Any comment?

 

[dieselherb]

(reply to post at 06:57:07 12/31/20) [

That's the one I got out. Don't understand why control is reversed. Also won't hold position, either going up or down!

 

[Bret4207]

Are they in the correct positions according to the manual? Sounds like maybe someone was in there before you.

 

[dieselherb]

Looks like it. Looking from back of tractor, one on left is smaller right side was threaded

 

[mEl]

(quoted from post at 10:17:43 01/01/21)
Looks like it. Looking from back of tractor, one on left is smaller right side was threaded

If the arms raise when the lever is pushed to lower the selector is in the draft control position, that is what it is supposed to do to transfer weight manually as you pus the lever front, Pull the lever back hard and switch the selector control to a different setting.