Open vs closed center Hyd

[Jeff Wenner]

I here these terms thrown around alot in these forums, could someone please explane to me what is meant by open and closed center hydraulics?
Thanks

 

[Spotted Horse]

Open center flows oil all the time, unless you move a lever to block the flow, diverting the oil to move your cylinder.
Closed center has constant pressure, but only flows oil when it is needed by opening a lever.

 

[Tx Jim]

To add to what Spotted Horse stated:
Closed-center hyd pumps turn while engine is running same as open center pump but stop pumping oil when a set (stand-by) pressure is attained. This is accomplished on a JD by the pressure oil in crankcase of hyd pump forcing pistons away from rotating pump shaft which in turn stops pump from pumping oil. This pressure build up inside crankcase is the result of the stroke control valve closing off an orifice therefore creating the crankcase pressured oil.

 

[Josh in WNY]

Jeff,

When the control valve for the hydraulic is in the center or neutral position on an open center system, the oil flow is routed to return and continuously flows.

On a closed center system, the flow of oil is stopped when the valve is centered. If the hydraulic pump does not have a relief valve or is not a variable displacement pump like Tx Jim described, then the system will over-pressurized and something (hopefully not you) will be damaged.

The advantage to a closed center system is that it usually has a faster response time to demands on the hydraulic system. They also tend not to heat the oil as much since the oil is not continuously flowing.

Josh in WNY

 

[Tx Jim]

(quoted from post at 13:27:38 03/15/10) Jeff,

They also tend not to heat the oil as much since the oil is not continuously flowing.

Josh in WNY

Exception to your rule is if closed-center has a large internal high pressure leak oil heats very quickly.