Front is Loader is very weak.

[Tom Wilt]

I have a 990 David Brown with 3 forward gears and Hi and Low Range. The 3 point lift is working normal and will pickup anything attached to. The front end loader will lift but will not lift any thing much heaver than the lift arms and bucket empty.

This happened very quickly. Brute strength one day and weak the next day.

Any help appreciated.
 

[RGMartin]

Hard to guess without more info.

How is the loader oil supply plumbed?

Remotes/ 3-way valve/ power beyond????

How much pressure do you have on the hydraulics?
 

[old]

With out more info hard to say. Could be a cylinder seal that blew out or a suction hose that has gone bad and restricting flow
 

[mEl]

[RGMartin]

Possible. 40+ year old o-rings are certainly suspect.

I would look at the bypass valve first. I have had them be "lazy" due to crud in the system to the point where you only get 300-500PSI out of the valve. 3-500 PSI will make the rockshaft lift pretty well but would make the loader a dog.


Another question, what is the condition of the hydraulic oil, and when did you last change the hydraulic filter?
 

[James of Stark]

Do you have any pages out of the service and repair manual detailing the hydraulic system for the 430s?
 

[Tom Wilt]

Thanks to all of those that replied. If I could figure out the nomenclature, would really be helpful.

Yeah the tractor is 40+ years old and has never had any repairs to engine or powertrain, other than starter and possibly an alternator. I did put new hydraulic value control on and it still acted the same. I do have a hydraulic pressure gauge, if I can find it. It was one of those things I bought a few years ago in case I needed it. I changed the hydraulic oil about a year ago.

Since the 3 point hitch works fine, I will first start with the main supply line to loader. David Brown has a peculiar system to operate the loader. There is a flow control value that the operator has to flip with his left hand, just below the seat, on the side of the casting. To operate the 3 point hitch the value has to be flipped in the other direction. The 3 point and FEL can't be used at the same time. My dad bought the tractor new and it has a DB loader. That setup never seemed right to me. Surely, that is not normal? I would like to change that if I could. I don't know anything about hydraulic. I just tinker around until I fix it. Only know I fix it when it works right. Sometimes, I am not even sure what I did.
 

[Jim in Sask]

That sounds odd, but possible I guess. I use the 3-point and the remote valve concurrently on my 885 all the time on a snowblower, no switching involved. Since it's a DB loader maybe they designed it like that for some reason.