Reservoirs & Valves

  • 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.