OPen center circuit

[porschemeyery]

Hi,
i am working for a compagny that sell CAN Actuator for agricultural valve like the one mounted on the 6000 JD Tractors. In order to understand the product of our customer i try to figure out how work an open center hydraulick circuit with more than one valves? Untill now i get trouble to imagine how the system keep pressure?

Thanks in adavance for your help

 

[MikeHalloran]

I don't know anything about stack valves.

In an open center circuit with one valve, the pump pressure is ~zero (and flow just goes back to the tank) until the valve is moved away from center. Then the pressure rises enough to move the load.



Mike Halloran
Pembroke Pines, FL, USA

 

[hydtools]

The system uses a valve stack with what is called a power-beyond feature. Flow passes through the valve stack until one of the valve functions is activated and directs flow to that function.
Here is an explanation reference:

http://www.insidersecretstohydraulics.com/power-beyond.html

Ted

 

[juniorhoss]

That's the normal operating status of an open-center system. Pump delivers full flow at zero pressure because it just circulates through the valve back to the tank with no restriction.

Acuating a function makes the pressure rise just enough to overcome whatever load is being applied (more demand for work equals more pressure).

When the load stalls (such as a cylinder hitting the end of the stroke) the pressure goes to relief valve setting.