Hydraulic reservoir sizing: One gallon of capacity per one GPM of pumping capacity.
Reservoirs should be tall and narrow rather than short and wide so as to reduce vortex effects
and improve heat dissipation.
Open-center, open-center-power-beyond and closed-center are terms used to describe
hydraulic valves in the neutral position.
Open-Center - used with a fixed-displacement pump, allows oil to free-flow back to the tank in neutral position. Shifting the spool redirects oil to the selected work port.
Open-Center-Power-Beyond - Same as Open-Center valve except oil flows to downstream circuit in the neutral position instead of returning to the tank.
Closed-Center = Typically used with a variable-displacement pump, oil flow is blocked at the valve until the spool is shifted from neutral.
Motor-spool - In the neutral position fluid is allowed to flow back to the tank. This allows the operator to run a hydraulic motor under load and, when the valve is shifted to stop flow to the motor, allows the motor to coast to a stop.
Cylinder-spool - In the neutral position fluid is blocked from flowing to the tank. This effectively locks the load in place and should be used in applications where a load is to be raised and held aloft with a hydraulic cylinder.
Three-way valve - Typically used to control single-acting circuits.
Four-way valve - Typically used to control double-acting circuits.