Have you checked the dump valve on the accumulator is closed?

Rich

PRA

Do the other pumps work OK?

That pump is smaller than the rest.

You need to describe the machine and the operation much better, but if there is a leak then you need to go find it by a person looking for the oil spurting out somewhere.

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Also: If you get a response it's polite to respond to it.

I imagine that your two compensators are set to different pressures and give you a two-stage response when the solenoid valve is energised. The upper compensator on its own will provide a limited flow to the stroking cylinder (and is presumably there to provide a soft landing), while the lower compensator allows the stroking cylinder to move at full speed.

It's not really clear what valve you operated when you "closed the pump delivery" - that would be useful to know.

Can you see whether the pump is on stroke? Knowing whether it is delivering lots of flow but with that flow not developing pressure, or simply not delivering flow (because the compensator is holding it off-stroke) would help you narrow the problem down.

Is the solenoid on the valve at EV11 energising (test with a solenoid pen, not just with a voltmeter)?

If I was on-site and not in the mood for thinking too hard, I'd probably pull the orifice at position 122 out and check it isn't blocked before doing much else. Lazy, but surprisingly often successful.

If the pump is on stroke, then have a check round the manifolds fed by that pump and check whether anything is unusually noisy or hot.

@LittleInch. The problem with hydraulic systems is that they sometimes provide opportunities for oil to leak across valves from a pressure to a return line. Relief valves and actuator piston seals are prime sites for this - and when it happens, it's all internal - there's nothing visible.

A.

Hello,
To detect an internal leak on a noisy installation, here is what I do:
I let the machine run without cycling for a long time. With obviously in the state of cycle which has the defect. If needed 30mn to 2h. And I'm going to drink a beer .... Then I take an infrared thermometer and I know where the hot oil is going. You should know that each time the pressure drops by 100bar in a component without providing mechanical energy: its temperature increases by 5.5 ° C.
Good luck

Zuesfaber - Fair enough, I was being a little flippant.

I can work myself around a P&ID pretty well by now, but fluid / hydraulic diagrams are still utter spaghetti....

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

moobe, The pump you are asking about is a pilot operated variable displacement pump. That means it requires system pressure in order to operate the mechanism that varies the displacement. If there is no pressure in the system the pump will not be able to increase stroke and move fluid. Your system may not be able to run with one or the other pump. It requires both.

Quote (TugboatEng)

If there is no pressure in the system the pump will not be able to increase stroke and move fluid.

It is not the pressure that increases displacement in a variable piston pump. It is a mechanical spring that is making sure the pump displaces fluid at startup. The pressure build-up helps the pump to compress that spring and decrease the pump displacement.

Quote (akkamaan)

It is a mechanical spring that is making sure the pump displaces fluid at startup

Some of them are like that, but not all. Most of the types I've worked with are positioned solely by hydraulics, but have a dedicated servo pump - either integral or running off the same shaft - to provide the power to do that.

A.

Correct if you have another source of hydraulic pressure ie charge/servo-pump...
Usually these pumps are bi-directional and most commonly used in closed loop hydrostatic drives for mobile equipment

How about EV3-7?

Fittingly, the guy asking for help doesn't give a sign of life. Neither thank you nor if his problem is solved and how.
My conclusion: Forums can help me learn new things, but I am disgusted by the rudeness of seekers. I won't help anyone anymore.

I hope you realize, in retrospect, how silly and immature that statement sounds. You are only hurting yourself. But you are probably just venting your irritation, and do not actually believe it.

To be fair the OP last logged in to post the question and hasn't logged in since.....

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.