how much loader drop is acceptable?

J_J · Dec 22, 2011

California,

If you would like joystick operation, then look at this valve .

Surplus Center - 2 SPOOL COMPACT 10 GPM JOYSTICK CONTROL VALVE

http://www.surpluscenter.com/Instruct/I9-7401.pdf

oldnslo · Dec 22, 2011

MF1652,
Does your loader drift down all the way to the ground or only drop a couple of inches and stop?

If clear to the ground your DCV is leaking.

Explanation based on this being a double acting single rod cylinder and both ends are full of oil.

With the cylinder extended and the DCV valve centered, this should block both cylinder ports.

With the cylinder ports blocks the cylinder can NOT retract due to there is no place for the oil to go.

example: 2 1/2"' bore cylinder with 1 3/8" rod & 24" stroke.

blind end of the cylinder holds 117.8 cubic inches of oil.

Rod end holds 82 cubic inches of oil.

That is a difference of 35.8 cubic inches so unless the DCV valve is leaking or their is an external leak the cylinders will NOT retract fully.

Roy

Mace Canute · Dec 22, 2011

X 2 oldnslo! :thumbsup:

J_J · Dec 22, 2011

When a valve is leaking, where does the fluid go, to the return port, or return to the main gallery.

If the valve is in fact leaking, then you should be able to see it after raising the loader and then removing the hose to the return port or PB port.

J_J · Dec 22, 2011

oldnslo; said:
MF1652,
Does your loader drift down all the way to the ground or only drop a couple of inches and stop?

If clear to the ground your DCV is leaking.

Explanation based on this being a double acting single rod cylinder and both ends are full of oil.

With the cylinder extended and the DCV valve centered, this should block both cylinder ports.

With the cylinder ports blocks the cylinder can NOT retract due to there is no place for the oil to go.

example: 2 1/2"' bore cylinder with 1 3/8" rod & 24" stroke.

blind end of the cylinder holds 117.8 cubic inches of oil.

Rod end holds 82 cubic inches of oil.

That is a difference of 35.8 cubic inches so unless the DCV valve is leaking or their is an external leak the cylinders will NOT retract fully.

Roy

Your logic is sound, but

Fully retracted might physically place the bucket several inched below ground.

Might also have something to do with the size and shape of the bucket and the mounting pins are located. Just saying.

Check the cyl rod to see if fully retracted.

MF1652 · Dec 22, 2011

J_J said:
Are you using cables to operate the valves. If so, cables might be binding and not allowing the valve to center.

There are springs in the valve, which are supposed to center the valve to neutral. If one of the springs is weak or broken, spool won't center, and may leak. The detent may also have rust, debris in the detent groove.

Most likely, your loader cyl's seals are leaking.

Can you max out the loader cyl's and get the relief valve to activate?

I'm going to pull the cover off this coming week to see what I have. I don't think it uses cables, but I'll see. It's a cab tractor with the control lever tucked under the console so I don't think there will be rust or debris in there(probably find a mouse nest with my luck). I'm struggling to learn the hydraulics on this tractor so bear with me. If one of the lift cylinders has a leak wouldn't the second lift cylinder keep the loader up? Or would they both fail together? How would I know when the relief valve is activated?(Don't know where or what that is:ashamed

oldnslo said:
MF1652,
Does your loader drift down all the way to the ground or only drop a couple of inches and stop?

If clear to the ground your DCV is leaking.

Explanation based on this being a double acting single rod cylinder and both ends are full of oil.

With the cylinder extended and the DCV valve centered, this should block both cylinder ports.

With the cylinder ports blocks the cylinder can NOT retract due to there is no place for the oil to go.

example: 2 1/2"' bore cylinder with 1 3/8" rod & 24" stroke.

blind end of the cylinder holds 117.8 cubic inches of oil.

Rod end holds 82 cubic inches of oil.

That is a difference of 35.8 cubic inches so unless the DCV valve is leaking or their is an external leak the cylinders will NOT retract fully.

Roy

The loader drops all the way to the ground.

I'm going to also disconnect the loader after raising it to isolate if it's the cylinders leaking or the DCV. I'm concerned I'm not going to be able to connect the loader hoses back up after this so if anyone has any good ideas on how to relieve the pressure to make the connections, I'm open to suggestions. I was thinking maybe place a jack under the loader bucket and use that to take the pressure off to make the connections. Good idea? Bad idea won't work?

Thanks folks.

J_J · Dec 22, 2011

There is nothing to separate the cyl, so if a cyl is leaking both will appear to be leaking. You have to separate the cyl to check for leak. Some tractors might only have one cyl for curl.

You have to use something like a jack to relieve the pressure.

A rope tied off in a tree might work also.

oldnslo · Dec 22, 2011

J_J said:
When a valve is leaking, where does the fluid go, to the return port, or return to the main gallery.

If the valve is in fact leaking, then you should be able to see it after raising the loader and then removing the hose to the return port or PB port.

It will leak to the path of least resistance. If an open center circuit this could be both tank galley and pressure galley so removing the PB hose and blocking it may not stop the drift.

Closed center system it would be the tank galley.

Roy

J_J · Dec 22, 2011

Roy,

What I was getting to was that if the valve is leaking, with the loader raised, and you removed the PB, and return lose, you should be able to see and collect the fluid from the cyl leaking out the ports.

oldnslo · Dec 22, 2011

MF1652 said:
The loader drops all the way to the ground.

I'm going to also disconnect the loader after raising it to isolate if it's the cylinders leaking or the DCV. I'm concerned I'm not going to be able to connect the loader hoses back up after this so if anyone has any good ideas on how to relieve the pressure to make the connections, I'm open to suggestions. I was thinking maybe place a jack under the loader bucket and use that to take the pressure off to make the connections. Good idea? Bad idea won't work?

Thanks folks.

If you enough patience there is another check you can do before disconnecting any hoses.

With the tractor running very slowly start moving the lever until the loader just starts to raise. Mark this position.

Now slowly move the lever until the loader just starts to lower. Mark this position.

Let the lever go to its spring center. Are the two marks close to the same distance from center location?

If there is a significant difference in the distances I would suspect some thing has jammed in the linkage. Not real scientific but it may give you a clue.

On a tractor that is only 1 - 2 years old I would suspect a valve issue before a cylinder.

Roy