Relief Valve in Cylinder Circuit with Counterbalance Valve
Relief Valve in Cylinder Circuit with Counterbalance Valve
(OP)
Hi there,
I'm looking for some advice on a circuit.
In the attached schematic, could anyone foresee any issues with setting the counterbalance valve (CB1) to 210 bar, and removing relief valve RV2?
Settings:
RV1 = 190 bar
RV2 = 210 bar
RV3 = 90 bar
CB1 = 250 bar
Thanks
I'm looking for some advice on a circuit.
In the attached schematic, could anyone foresee any issues with setting the counterbalance valve (CB1) to 210 bar, and removing relief valve RV2?
Settings:
RV1 = 190 bar
RV2 = 210 bar
RV3 = 90 bar
CB1 = 250 bar
Thanks





RE: Relief Valve in Cylinder Circuit with Counterbalance Valve
How will you raise the cylinder? If the working pressure required is 210 Bar, you will relieve through RV3 (90Bar), so the cylinder wont move.
You seem to have to many relief valves, Why dont you just use one R.V. and one C.B.
Also, you should use an open centre directional valve.
RE: Relief Valve in Cylinder Circuit with Counterbalance Valve
If a load is placed on the cylinder that causes the pressure to rise above 210 BAR, what will protect the cylinder? It could be that the cylinder will buckle above 210 BAR.
The directional valve is open centre, it has 6 ports and 3 positions.
The 190 BAR relief valve (RV1) will limit the dynamic pressure, the pressure at the pump.
RV3 sets the maximum lift pressure.
The cylinder will lower at approx 166 BAR.
You need to verify the cylinder buckling calcs before you remove RV2.
RE: Relief Valve in Cylinder Circuit with Counterbalance Valve
The control valve is not open centre, look at it, it has 4 ports blocked in middle position!
Why dont you just use a simple circuit like htose here: http://www.comatrol.com/application-notes
RE: Relief Valve in Cylinder Circuit with Counterbalance Valve
The counter balance valve is set to 250 BAR and will open at 166 BAR if there is a pilot signal from the rod side of the cylinder to push the valve open.
With no pilot signal, the counter balance valve is just a relief valve set to 250 BAR.
RE: Relief Valve in Cylinder Circuit with Counterbalance Valve
HPost is correct in that the pump is connected to tank when the directional valve is centered.
Ted
RE: Relief Valve in Cylinder Circuit with Counterbalance Valve
With the working load applied the pilot pressure will need to be 26.7Bar to lower the cylinder. But it doesn't matter anyway as RV2 will open at the working pressure.
why not just use a simple circuit like this (http://valveproducts.net/upload/images/counterbala...) with perhaps an additional RV after the pump.