 You DO need a closed center valve. Some are convertable, some are not. The open center valve passes the oil at low pressure when there is no hydraulic load and the system only develops pressure when a cylinder has a load or gets to the end of its stroke. The closed center system holds pressure and only passes it to a cylinder when the valve is opened. When there's no hydraulic work being done there's lots of pressure, but no oil flow in the closed center system. The open center system releives excess pressure with a pressure relief valve. The closed center system maintains pressure to reducing the pump stroke when pressure is at the system setting. It generally takes two changes to an open center valve to convert it to closed center. One is replacing the pressure relief valve with a "no relief" plug. The other is replacing the power beyond plug with a closed center plug. Cost me about $40 when I changed over my loader valve moving the loader from a MF to my 4020. You will probably also want a flow restrictor valve feeding the loader valve to keep from having to finesse 20 gpm to cylinders that need only 5 gpm for reasonably fast motion. I made up a manifold on the side of my 4020 for the loader and a back hoe. The picture is of that manifold after several years of farming. Gerald J.
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