center system that has more than one selector valve, the valves are arranged one behind the other (in
In a closed-center system, the valves are arranged parallel to each other. An open-center system has
fluid flow but no pressure in the system when the selector valve is off.
In a closed-center system, fluid is under pressure throughout the system when the hydraulic pump is
operating. Both systems are discussed in the paragraphs that follow.
Open-Center System. Figure 2-7 shows a basic open-center hydraulic system which uses a relief
valve to limit system pressure. As was mentioned earlier, this type of system
Figure 2-7. Basic Open-Center Hydraulic System.