[Chris Stone]

Hey guys I purchased a David brown 880 a couple years ago. I was using the slasher in the paddock and got stuck in a ditch. Ever since then as soon as I start the tractor up the lifting arms raise all the way up and I cannot move them at all. Has this happened to anyone else before?

 

[FredM]

G'day Chris, welcome to the forum

Where is the selectamatic lever set to, the 3 position small lever on the right beside the seat and slightly behind, this should be set on "depth setting", for usual work, never on TCU setting, when you shift the selector lever, you should pull the draft control lever to the rear against the spring pressure and then shift the selector.

I can attach a workshop sheet for the hydraulics for DB, would cover your tractor and 990's up to 1210 if you want.

There is also a transport latch on the rockshaft, I think this is on the left rear, this is a curved handle that should be in the raised position, when down, this latches the rockshaft and if the links are raised, then you cannot lower with the lever in the down position

Also check the lowering speed control, that hasn't been closed off, the links wont lower when the valve is closed.

 

[Chris Stone]

Hi Fred.
Thanks for your reply.
I had the lever set to the height position.
A workshop sheet would be great as I’m not 100% sure as to how the hydraulic system works.
I am at work at the moment so will have to check everything else once I get back.

 

[FredM]

Here you go then, heavy reading, take your time with it, and please don't try adjusting the control valve unit without the special setup tool, measurements and shape is in the pdf.

 

[Chris Stone]

Thanks heaps mate. Will have a look once I’m home next week.

 

[Chris Stone]

I just got back and had a look.
The selector switch won’t move when the control lever is pulled against the spring pressure. It only moves when it is not against the spring pressure.

The lowering speed control knob is very hard to turn but it is set to the faster option.

And the transport latch is set to the raised position.

Unfortunately it still just raises as soon as the motor is started.

 

[FredM]

I just got back and had a look.
The selector switch won’t move when the control lever is pulled against the spring pressure. It only moves when it is not against the spring pressure.

The lowering speed control knob is very hard to turn but it is set to the faster option.

And the transport latch is set to the raised position.

Unfortunately it still just raises as soon as the motor is started.

G'day Chris, I re-read your post and was wondering when the tractor got bogged, did this sink deep enough to have the slasher push against the top link mount on the rear of the tractor, this top link mount is the sensing unit for depth and height control, if this was the case, check and see that the mount hasn't been pushed into the housing and has stuck, this will give you the raise with no control...

Go to page 81 of the PDF I attached for you and section 244, which explains the settings for the top link sensing control and after reading, check the cable and the top link mounting, figure 183 shows the mount sensing unit.

You may try raising the slasher off the ground enough to bounce on the rear a few times to see if the top link mount is moving, start the engine and when the slasher clears the ground, turn engine off and jump on the rear a few times, sounds silly, but!!.