Hydraulic pump supply options

Learn about different pump type power unit designs

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Topics and outcomes

Expected outcomes: Understand the impact of open center vs closed center valves used with fixed and variable displacement pumps including their operating efficiencies.

Level: 2-4 Novice to improver

Topic covered: Fixed displacement pump power supplies

  • Power unit design energy efficiency
  • Comparing open center with closed center design
  • Comparing circuit operation with series and parallel valves

Fixed displacement pump with open centre valve

fixed pump and valve

Question: What is the pressure at the pump

Experiment: Open circuit Supply/1 Fixed Pump Experiment. Place test gauge on pump. The flow passes straight through the valve to tank. The relief valve is shut.

Experiment Link

Question: Why is the pump pressure so high when no useful work is being done

Experiment: Place test gauge on each pipe to see how pressure changes around the circuit. Click on the pump and adjust the flow rate to see how this affects the pressure.

Experiment Link

Question: What pressure is seen at the pump with the cylinder moving

Experiment: Click on each solenoid valve and measure the circuit pressure with the test gauge. Double click the cylinder to stop/start it moving. Drag the small print icon to the pump then click the larger top print button to save the results.

Experiment Link

Question: What causes the pump pressure when the cylinder is moving

Experiment: Click on the cylinder rod to open the load setup window. Change the frictional load and observe how the pressure changes. Drag the small print icon to the pump then click the larger top print button to save the results.

Experiment Link

Question: What pressure is seen at the pump with the cylinder at its end stops

Experiment: Extend and retract the cylinder to its end stops and record the pump pressures. Click the larger top print button to save the results.

Experiment Link

Question: What controls the pressure at maximum cylinder extension

Experiment: Move the test gauge over the pipes to see the flow paths. Place the gauge on the relief valve. Observe how the relief valve symbol changes.

Experiment Link