Here is some more on hydraulics in tractors for anyone following along.
The way an open center hydraulic system works is simplicity - a fixed unvarying hydraulic pump just circulates fluid through the system continually. The flow goes around in an endless loop. But there is no pressure anywhare in that fluid loop until a control valve is moved to block some part of that flow. Then pressure is built up there, trapped, and some work gets done. Extra fluid goes back into the endless loop.
The advantage to an open center hydraulic system is that pressure is only stored in the hydraulic cylinders, and then only when they are working. So components are way simpler, less expensive, and last longer.
The disadvantage is that the tractor engine is always driving the hydraulic pump which is continually circulating fluid. That wears on a system, and also continually costs both efficiency and fuel.
The way some closed center JD ag tractor hydraulic system works - like the 2030 - is that the hydraulic pump can vary the flow it puts out from zero to full flow. The first time the tractor is started, the pump goes into full flow mode and fills up a pressure reservoir with high pressure fluid. Control valves and cylinders can then call on that reservoir for high pressure fluid as needed. After filling the high pressure reservoir, the pump goes into "no flow" mode, and only pumps when it needs refilling.
The advantage to a closed center (JD) hydraulic systems is that full pressure is instantly available, and the tractor engine isn't constantly spending hp and fuel circulating fluid in a loop that isn't doing anything. That advantage is part of why the JD ag tractors are economical on fuel.
The disadvantage is that storing pressure also wears on a system. Plus there is the argument that a closed center having to constantly store pressure requires more complicated & expensive parts compared to the open center type of system.
Hope this helps,
rScotty
