Please splane power beyond vs. open center

[shaley]

What is the difference between power beyond and open center. I thought open center was the same thing. Can anyone elaborate.

 

[MadReferee]

They are two entirely different terms.

On an Open Center system, the pump is always pumping so the valve must allow fluid to pass thru when all spools are in neutral.

Simply for power beyond, a valve that has power beyond will also have a seperate return to tank port. When a spool is activated neutral pressure fluid flows from the cylinders out thru the tank port and back to the sump/tank while excess fluid not being used by the spools continues to flow thru and out the power beyond port and on to additional valves. Aditionally, if the valve has a pressure relief it will dump fluid to the tank port instead of back to the main flow. On valves without power beyond there is no return to tank port. Neutral pressure exhaust fluid is dumped back into the main flow rather than directly back to the sump/tank. Valves further on in the circuit may have problems if actuated simultaneously.

 

[shaley]

Oh, I see. Dump from cylinder can't be routed to OC port in this case because it is at or could be at system pressure with down stream spools actuated. Thanks for the reply.

 

[Dusty]

Understanding hydraulics is complicated, but when you see it in diagram form, it get real simple quickly.