Adjusting a Load Sensing Pump

[@antonuskov4376]

Hello, I’ve got A10V pump with power control (DFLR). When I tried to adjust it, nothing changed. How does it work? As at full load a motor trips on overcurrent

[@islanduni]

Is the loading valve that determines which pressure to be used in the pump itself? I have a EATON 70422 and working on a personal install. Thanks Jim

[@Gpmhydraulic]

That is correct - in the configurations shown in the video, the loading valve determines the pump standby, or idle pressure. 200 PSI if the loading valve is de-energized, 1950 PSI if energized. This reduces energy consumption in systems that idle any significant amount of time.

[@samerasaad7010]

Please advise what is the best margin value to adjust in order maintain hydraulic motor steady speed with load sudden fluctuation?

[@Gpmhydraulic]

Thank you for your comment, Samer! I'm not sure exactly what you mean by margin value, but a large part of the purpose of the load sensing pump is to maintain a constant speed of the actuator despite changes in load pressure. I believe what you are asking is how to keep sudden pressure spikes from instantaneously affecting speed. The load sensing valve and compensator valve are not responsive enough to absorb spikes, so it is possible for brief changes in speed to occur when spikes appear. The answer to eliminating spikes in a hydraulic motor circuit is crossport relief valves. These direct acting valves do a much better job of absorbing sudden pressure changes. Consider installing these if your system experiences sudden pressure changes. Not only will they help avoid sudden speed changes, but they will also help to protect the motor from shock. Hope this helps!

[@samerasaad7010]

Thank you for your interest to answer me such high technical replay. When I talk about margin I mean flow compansitor spring adjustment. In other orders what is the difference between set it high or low? How would these different settings effects the system. On the other hand I believe double cross relief valves need closed center dirictional control while one I have is y shape.

[@Gpmhydraulic]

I understand what you mean now. A good starting point is to set the compensator about 200 psi above the heaviest load pressure. Too low and you will get stalling at heavy load, too high and you get system shock. You probably don’t need crossport relief valves since you have the float center directional valve. But just so you understand, they don’t actually require a closed center. The opposite IS true, however - motor drives with closed center valves usually DO require crossport relief valves.

[@samerasaad7010]

@@Gpmhydraulic thank you very much for your assist and awesome discussion.

[@guruv1870]

Suppose if no return line is connected for load sensing then what is the affect of tightening or loosening load compensating adjustment screw

[@Gpmhydraulic]

Thanks for your question! There is always a return line connected, but you can’t see it because it goes to the pump case and returns to tank through the case drain.

[@guruv1870]

But you have shown 4 output line from pump 1 suction, 1 delivery, 1 going to dc valve and 1 output P line connected to relief valve and 1 leak line

[@guruv1870]

What i mean to say is that what If there is no load Sense signal hose is connected to pump? Then what is affect of tightening and loosening of load sensing setting screw

[@JackWeeks]

@@guruv1870 , Oh, OK, I see what you mean. If there is no load sense signal applied, the compensator valve setting will override the load sensing setting. Sorry, I misunderstood your question. Quite often, these pumps are specified by the designer because of their efficiency even though the load sensing feature is not needed.

[@guruv1870]

@@JackWeeks yess, means i can fully tightened it in order to disable this feature because no load sensing line is actually connect to it...

[@ajitnayak2126]

Hello sir, Myself Ajit Nayak from INDIA, I have Rexroth A10VSO100-DFLR-31R pump. before few days my team replace rotary kit in this pump. i request to you pl. guide me to set up Pressure, Flow control as well as load sensing valve optimum setting. my CNC machine required pre. is 3200 PSI, 50HP Motor using in this system. Thanks GPM Hyd. Team.

[@Richard-dv9nr]

If the p comp is set to 1950 and the ls is set to 200 wont the pump only make 1750 to the rest of the system?

[@Gpmhydraulic]

No, the two settings are independent. The normal pressure will be 1950 PSI and will reduce to 200 PSI when the pump goes into standby.

[@Richard-dv9nr]

@@Gpmhydraulic Ok if the the load is 900psi, the pump generate the 900psi + 200psi pressure drop from the load sense setting which equals 1100psi right. So what happens to this pressure drop when the load is at 1950psi? Would the pump not have generate 2150psi to account for the 200psi pressure drop across the load sense?

[@Gpmhydraulic]

@@Richard-dv9nr , if the load reaches 1950 PSI, it will begin to stall. The pressure at the outlet of the pump is limited to the compensator setting at all times. There will no longer be a pressure drop across the flow control, because the load pressure will equal the compensator setting. From the point where the load pressure is 1750 PSI, the pressure drop across the flow control will decrease as load pressure increases, so the speed of the load drops. Once the load pressure reaches 1950 PSI, the load will stall altogether.