Loader Woes

[JimR]

One other thing that was happening today is this. If I switched the the FEL lever from the up to down position the loader would jump up in the air while I was switching the lever to down. I assume this was just from the built up pressure in the high pressure pump line causing this. I will have to try the return line in a bucket trick to see if that alleviates my problem. If not then the FEL valve gets removed again. Thanks for all the help guys. Now to just find the time to dig into it a little bit deeper

 

[3RRL]

Jim,
You post further encourages me to think your valve is not operating properly. Think about it. The only time your fel should go up is when you move the lever to "up". Otherwise you spools are not working correctly. Especially from up to down. They are letting fluid flow into the "up" mode when it shouldn't. Some functions allow simultaneous movement of two directions, such as lift and curl or lift and dump. Also down and curl or down and dump. But they are plumbed to do that. I don't think that up and down are, since they are opposite movements.

If they could do that, which they shouldn't, your up and down would counter each other and the fel would not move. In your case the port with the least resistance is winning and letting a little more flow in that direction, but it is still being "fought" by the leak in the other direction. Hence super slow movement with the pump under strain. That would also explain the "tight" hose because the valve is trying to lift and exhaust from both ports. So your system is under pressure but the fluid has no place to go like normal, except maybe through the relief valve.

Maybe the restriction or wear is when you have the lever in full up position. As you pull it to get to the down position, it passes through that area where you said the fel works when feathered, or slightly on...which allows proper flow and function. That may be for a split second, but the fel responds to it and jumps up? My money is still on a bad valve or debris.

 

[SPYDERLK]

One other thing that was happening today is this. If I switched the the FEL lever from the up to down position the loader would jump up in the air while I was switching the lever to down. I assume this was just from the built up pressure in the high pressure pump line causing this. I will have to try the return line in a bucket trick to see if that alleviates my problem. If not then the FEL valve gets removed again. Thanks for all the help guys. Now to just find the time to dig into it a little bit deeper

Could be a moment of pent up return flow thru the PB line as the spool shifts. That would just be a slight imperfection in valve port sequencing and may in fact fit the rtn hose hypothesis.
larry

 

[JimR]

Jim,
You post further encourages me to think your valve is not operating properly. Think about it. The only time your fel should go up is when you move the lever to "up". Otherwise you spools are not working correctly. Especially from up to down. They are letting fluid flow into the "up" mode when it shouldn't. Some functions allow simultaneous movement of two directions, such as lift and curl or lift and dump. Also down and curl or down and dump. But they are plumbed to do that. I don't think that up and down are, since they are opposite movements.

If they could do that, which they shouldn't, your up and down would counter each other and the fel would not move. In your case the port with the least resistance is winning and letting a little more flow in that direction, but it is still being "fought" by the leak in the other direction. Hence super slow movement with the pump under strain. That would also explain the "tight" hose because the valve is trying to lift and exhaust from both ports. So your system is under pressure but the fluid has no place to go like normal, except maybe through the relief valve.

Maybe the restriction or wear is when you have the lever in full up position. As you pull it to get to the down position, it passes through that area where you said the fel works when feathered, or slightly on...which allows proper flow and function. That may be for a split second, but the fel responds to it and jumps up? My money is still on a bad valve or debris.

The spools looked perfect when I took the valve apart. I wonder if the O rings are gone and letting fluid bypass the spools into both sides at once. Is this possible?

 

[RonMar]

In most designs I have seen, The "O" rings typically are there to keep the oil from leaking out past the end of the spools. I was talking about the return pressure limitations on some valves, the return galleries are typically out on the ends of the spools, when you exceed the rated return pressure, it is usually the "O" rings that the oil leaks out past I think Spyderlk is right, it is just a bit of built up pressure causing the jump when you shift directions.

 

[JimR]

In most designs I have seen, The "O" rings typically are there to keep the oil from leaking out past the end of the spools. I was talking about the return pressure limitations on some valves, the return galleries are typically out on the ends of the spools, when you exceed the rated return pressure, it is usually the "O" rings that the oil leaks out past I think Spyderlk is right, it is just a bit of built up pressure causing the jump when you shift directions.

That was my first thought on the jumping also. Today I didn't get a chance to mess with it. I have too many other projects going on at the old farm right now. Sometime this week I will reverse the hoses and see what happens.

 

[MJPetersen]

Could be a moment of pent up return flow thru the PB line as the spool shifts. That would just be a slight imperfection in valve port sequencing and may in fact fit the rtn hose hypothesis.
larry

This is where I am too. I think that it is an accumulator effect of those filled to max PB hose(s). JMHO

Mike in Warsaw

 

[JimR]

I'm really confused now. This morning I unplugged the return line at the manifold on the engine block, and removed the quick disconnect fitting. I started the tractor up and ran the loader through as many cycles as possible before running out of fluid. I only had the engine idleing and killed it as soon as the fluid went low. I think I pumped about 4 gallons out of the tractor. It was really quick to unload that amount of fluid. The loader worked fine with no problems whatsoever. Hhhmm, I'm thinking this is not good. I then decided to pull the hydraulic manifold off of the engine block. This was not an easy task as the loader bracket covered the PB line to the back of the tractor. I also noticed that there is a heater hose bypass on top of this manifold that is directly above the return line. I get the block off and see that the rear return line and the bypass line are all connected via holes in the manifold. I now know that the problem is ahead of this manifold. If there was a restriction from the hydraulic manifold to the rear in the return section of the hydraulics. This heater hose bypass line would have blown up. So now I am back to square one. I find no problem with the return line. I checked the quick disconnects to make sure there is nothing blocking them. I put the return line back on and the loader worked fine for at least 30 complete cycles of up and down and curling the bucket. My only thought now is that there must have been something in the return line that was blocking the quick disconnect and blew out while operating the loader with the hose off. Totally confused as the piece should have been against the quick disconnect when I removed it. Time will tell if it keeps working right.

 

[Farmerford]

Maybe the obstruction floats in hydraulic oil. If so it would have stayed at the top of the hose until fluid passed through. And, if the flow were very low, perhaps it would not have been pulled down to the QD.

 

[JimR]

Maybe the obstruction floats in hydraulic oil. If so it would have stayed at the top of the hose until fluid passed through. And, if the flow were very low, perhaps it would not have been pulled down to the QD.

AAaaaah, good point. Maybe it was floating at the top of the hose. The oil came out of the hose so fast that there was no way to see it blow out.