Hydraulic systems use pressurised hydraulic fluid to manage hydraulic machinery. These hydraulic systems can take the form of an open centre or closed centre system.
Closed centre hydraulic systems supply fluid on demand to simultaneous operations connected to a single pump. Pressurised fluid flows constantly through the system via a piston pump.
Piston pumps use positive displacement, or move a fluid by trapping it, then displacing it into a pipe for discharge. Piston pumps use high pressure seals which reciprocate with the piston to move the fluid.
Closed Center Circuits
Closed centre hydraulic systems rely on closed centre circuits, or systems of interconnected components that move fluid, to provide pressure to the control valves, which partially or fully close or open, based on sensors that determine the level and rate of flow. The pump moves only minimal hydraulic fluid through the closed circuits until a valve is actuated by an operator. This allows the valve's spool to operate without an open return path to the hydraulic system's fluid reservoir. This configuration allows multiple valves to connect to different operations while sharing equal system pressure.
- Engineers Edge: Basic Hydraulic Closed Center System Schematic
- "Hydrology and Hydraulic Systems"; Ram S. Gupta; 2007
- "Fundamentals of Hydraulic Engineering Systems"; Robert J. Houghtalen & A. Osman Akan; 2009