Hydraulic system virtual test rig
Suggested exercises and observations
Constant load forces
1. Select Free>3 Cylinder Speed Control, from the drop-down list.
♦ Click on the cylinder rod to open the setup box.
♦ Note how the cylinder is horizontal so the mass will not generate pressure.
♦ Note how the force is acting on the bore so the cylinder moves while the directional valve is still inactive.
♦ Drag the test gauge over the cylinder body, this will display the pressure and flow values.
♦ Operate the directional valve to move the cylinder and observe the load pressure on the cylinder in both directions.
♦ Click on the flow control valves and change the orifice areas. Operate the directional valve to see the effect on the cylinder pressures.
Mass loads
♦ Reduce the load force and change the angle of the cylinder to observe the effect on the cylinder pressures.
♦ Experiment with the flow control orifice sizes required when the mass is pushing onto the cylinder rod and pulling it down e.g. 90 and -90 degrees.
Frictional loads
♦ Reduce the mass on the cylinder and increase the friction to above the driving force. ♦ Observe what happens to the movement while the directional valve is inactive.
♦ Operate the directional valve and observe how friction affects the cylinder pressures in both directions.
Further work on system loads
♦ Find the hydraulic circuit for one of your machines or look at a typical excavator boom arm cylinder. Draw a free body diagram to explain the loads that are acting on the cylinder.