Need an expert hydraulic opinion.

jenkinsph · Aug 11, 2014

From what I see in the diagram the power beyond has to feed thru the pressure relief to flow to tank. I would think there should be a return to tank from the valve body and the pressure relief line on the motor port should also return to tank. I don't see how what is in the drawing would work and also can't see how the gauge would be relevant at all, it could be plugged off for that matter.

How does the fluid leaving the motor return to tank?

J_J · Aug 11, 2014

The relief dumps into the EF flow.

jenkinsph · Aug 12, 2014

J_J said:
The relief dumps into the EF flow.

I looked at the drawing again and see that I mistook the plain tee for a relief valve. My mistake.

The relief is built into the flow control valve, that makes a lot more sense.

J_J · Aug 12, 2014

They make a similar valve with out the relief.

One other thing to consider is there is a relief on the FEL valve that will provide system relief so it might depend on the relief setting of the RD valve.

If the RD valve relief is set above the FEL relief, then both CF and EF will have relief, and if set below, then the CF only will have relief for that circuit. .

NCMau · Aug 12, 2014

The pic shows the connection to the FEL valve. I have not tried the jumper between the two QDs. I have to make one.
The point you made about the FEL and Control valve relief...they are different. The FEL is set for 2000 psi and the control valve is set for 1500 psi as it was received from Surplus Center. Is this effecting my issue?

J_J · Aug 12, 2014

That means that the flow control valve will relieve at 1500 psi in any situation.

Somewhere I remember that if you stop the flow to the CF port, you also shut off the flow to the EF port.

If you set the CF relief valve higher, then the FEL relief, it will be the master relief.

NCMau · Aug 13, 2014

J.J.
you are right. I did turn the CF PRV one full turn clockwise (I guess I increased the relief amount) and the pig did not squeal anymore. I did not have the gauge setup so I don’t know how much I increased it, but apparently it was enough.
I still don’t understand all I know about this valve. In theory when you shut off the CF, the fluid bypasses to the EF, regardless of any control valve PRV settings.
Is it possible that I have a defective valve?