Re-plumbed hydraulic's-Still have FEL problem

[juiceman39]

Here is a diagram of what I have. I added the gauge & filter.

juiceman39

 

[J_J]

juiceman39,

The way you have your system plumbed, will work to an extent, in the fact that if the pressure gets up to and above the FEL valve limits pressure, the FEL valve may crack or split because the outlet of the FEL valve is the weakest part of the valve. I don't think you have the PB port, or you would have used it. If you have full flow as displayed, and the filter is not blocked, then fluid should flow through the circuit OK. The ideal way is for the outlet of each valve to return to tank. I would assume that your BH has a relief valve on it. Depending on the BH relief setting, when you use the BH to the extreme, you may be generating large hyd spikes, causing the FEL relief valve to operate, or crack the valve.

With things as they are, If you move the lever to raise, you should have pressure on the A or B ports, which are the cylinders for the loader, and none or low pressure on the BH . You should have system relief pressure for the FEL circuit. Did you say the BH pressure was OK?

 

[juiceman39]

Yes BH works as it should. Before I re-plumbed the pump "out" went to the BH first. Then the BH "out" to the FEL "in". The BH does not have a PB, as I do have the book for it. Not sure what the relief should look like. But there was no strain on the pump the way it was plumbed before. maybe I should take it back to the way it was. Could the BH valve reduce the pressure/flow to the FEL valve? as I said the pump never overheated before.

juiceman39

 

[J_J]

juiceman39 ,

The pressure will be the same, but smaller lines, smaller fittings would have some effect on the GPM that can pass through. A cavitating pump will get hot. Check the input lines.
Air leaks and water will cause foamy fluid.

 

[juiceman39]

I did increase the line from the pump from 3/8 to 1/2. is there such a thing as to much GPM?

juiceman39

 

[Leejohn]

Check the BH valve and make sure all valves are in N.

 

[J_J]

I did increase the line from the pump from 3/8 to 1/2. is there such a thing as to much GPM?

juiceman39

Increasing the size of the lines to 1/2, only gave you the potential for more flow, more GPM, but you are limited by the pump volume. If the pump was designed for 8 GPM, then that is what you will get at a certain rpm. More GPM means faster cylinder action, or faster hyd motor if one was in use. If you had one of those heat guns, it would show you where the hot spots are. The fluid should not get above about 180 degrees, or damage will incur.

 

[J_J]

Check the BH valve and make sure all valves are in N.

My thoughts here are, that if any of the levers are in any position other than neutral, that you would see some action, such as a cylinder extended or retract, however, there is a possibility that a cylinder could be in the pressure mode, and forcing the cylinder to the closed position, and when enough pressure has built up, the valve will go into relief, and bleed off until relief pressure is met, as long as the pump is running . That will also keep the FEL valve at relief pressure.

The way to check this is to put the gage in line from the pump and FEL and see if the FEL valve has pressure on it. There should only be pressure at the gage, when a valve is being used, whether it is the FEL valve or the BH valve.

That might explain why the lift and curl cylinders do not work right, because the pump is keeping the in and out ports of the FEL valve at same pressure. If the same pressure is on both the in and out ports, there is no place for the return fluid from the FEL valve to go, hence, system locked up, and since the relief valve is operating, then the fluid will be hot, and there will be bubbles/foam in the system.

Anybody else want to jump in here and venture a plausible explanation. My logical conclusion may not be totally correct. Best I can do for the moment.

Again, this is not the best set up one can do, but if it is all you have, then it is what it is.

 

[juiceman39]

So with all valves in NEUTRAL, FEL and BH, the pressure should be down around 500 psi. Now it seems to me that it was at 1800 psi with no handles moved. If so then this would indicate some type of restriction or valve/spool not centering- correct. If there was a gauge on the return hose say at the filter, shouldnt it read the same as the gauge right off the pump, both at around 500 psi(if everything is at center) thanks for all the comments, it really gets me to thinkin'.

Is this correct: the relief, when PSI gets too high, diverts the fluid to the return line, thus lowering the pressure? I'm assuming the relief is under the acorn nut? there is a threaded bolt, then a spring, then a ball bearing.

juiceman39

 

[juiceman39]

Yee Haa, I have lift-off. what I did was remove the BH from the system completely, and the out of the FEL now goes to the tank. works at low RPM even. about 300 psi when FEL raising at low idle. Could it be the problem is in the BH valve not centering-not returning fluid?

Is there some kind of an inline PB or add on device. one in and two out type thing. So I could plumb both "outs" to the tank.

juiceman39