Do I Have a Bad Valve?

[BWBrown]

On my Ford 1700, Bush Hog front end loader, I have a question:
The joystick functions correctly, move it left and right, the bucket curls.
Move the joystick full forward, it has a float detent, not so far forward the loader is in power down mode.
Pull the joystick partially back, the loader rises - so far so good...

Pull the joystick full back, the loader stays where it is, the valve sounds like the pressure relief is bypassing. Is there an adjustment, or is my valve bad?

I don't know the manufacturer of the valve. I bought the tractor new about '80, sold it in '87 then bought it back in '93. In the meantime, the other owner had installed the FEL (Bush Hog 1846 QT). It has functioned this way as long as I have had it, but the need to use the loader lift only in partly back position is something of a pain - the ability to simply pull full back on the stick to raise the loader would be great.

 

[J_J]

If your loader has QD's, try reseting them. Are there any check valves in the loader circuit.

 

[AKKAMAAN]

just an idea.....
Check so the maximum spool movement in the valve is not exceeded...should be around 3/8 to 1/2" or so........if you can pull that spool out to far when making lift operation, the land on the spool can block the port....with relief by pass as result.....see attached pic....

 

[jinman]

AKKAMAN, you did a great job of illustrating and describing what the problem must be. The lift spool must be exceeding it's maximum UP travel and blocking the ports. I was going to suggest that there might be a stop adjustment that limits joystick movement that has backed off. I would expect that to be internal to the valve. . .not sure.

 

[AKKAMAAN]

AKKAMAN, you did a great job of illustrating and describing what the problem must be. The lift spool must be exceeding it's maximum UP travel and blocking the ports. I was going to suggest that there might be a stop adjustment that limits joystick movement that has backed off. I would expect that to be internal to the valve. . .not sure.

well then we are two about it now...
Thanks for the support...

btw a forum is a learning /teaching board for hundreds of viewers/readers aswell as just a individual help desk...and I have a long history 25+ years, teaching fluid power on logging equipment....so it is natural to me to "take the next step"....wish more "expert" members would do the same, and this forum would become even better.....

 

[J_J]

You might try switching hoses on the valve and see if the trouble stays with the spool. When you pull back on the lever, do you have any pressure. It should not be going into relief unless something is blocking the flow, or the cylinders are fully extended or retracted.

 

[BWBrown]

It happens at any point in travel - the cyls are not fully extended. I have checked the QD connections, switched the hoses, my feeling all along is along the lines as diagrammed by akkamaan, and jinman has hit it spot on, on so many other posts - thanks to all of you for your suggestions!

I have played with quite a few cylinders, pumps and valves, but never INSIDE them. I'm fully aware that the ability to screw in a hose does not make me a valve repair guy.

I see no external stops on the lift function of the joystick, but it really does act like it is just coming back/out too far.
Could there be an internal detent, shoulder, stop pin or some other such thing broken? Could it be as easy as an adjustment.

If it is an easy fix, I'll have at it, OTOH, I'm not opposed to completely replacing the valve. I've lived with it longer than I care to think about.

 

[AKKAMAAN]

as diagrammed by akkamaan, and jinman has hit it spot on, on so many other posts - thanks to all of you for your suggestions!

I see no external stops on the lift function of the joystick, but it really does act like it is just coming back/out too far.

There is nothing else that make sense......

Could there be an internal detent, shoulder, stop pin or some other such thing broken? Could it be as easy as an adjustment.

If it is an easy fix, I'll have at it, OTOH, I'm not opposed to completely replacing the valve. I've lived with it longer than I care to think about.

 

[jinman]

I'm just going to sit back and watch and learn. While I have a good feeling of what is happening, AKKAMAAN has all the experience and knowledge. So I'll just happily sit on the sidelines and listen and learn.

 

[Leejohn]

Me too. Go for it brown it's a easy valve to repair.