Directional Valve Testing

1. Select the 'Creep due to spool leakage' from drop-down menu 1. Click the question mark (?) and sound button for additional advice.

♦ Observe how the cylinder falls very slowly even though the valve ports are closed in the center position.

♦ Cylinder creep is due to the leakage across the spool gap.

♦ Operate the directional valve solenoids to raise and lower the cylinder.

2. Select the 'Uncontrolled cylinder drop' from the drop-down menu 2.

♦ Observe how the cylinder will fall in an uncontrolled manner with just a directional valve and no flow or speed control.

3. Use the forward and back arrows to guide you through the experiments. The floating window help screen provides advice.

Experiment 1: Select the creep due to spool leakage (drop-down menu 1). Observe how the cylinder falls slowly.

Question 1: Why is the cylinder falling while the valve is closed?

Fluid still leaks between the small spool clearance.

Experiment 2: Observe how the cylinder falls quickly. A directional valve simply controls the direction, not the flow.

Question 2: What is required to control the flow?

You need to add a flow control valve as well as a directional valve.

Experiment 3: Directional valves come in many different configurations.

Question 3: Which configuration is shown?

A 4 way, 3 position valve is used in the simulation.

Experiment with this directional valve circuit