Operate the valve with the slide bar and use the arrow buttons to explore each hydraulic principles
Basic Hydraulic Control Principles
Suggested exercises and observations
1. Select step 1 (dropdown menu 1) Pilot pressure against a spool
• Adjust the pilot pressure on the spool by dragging the slide bar.
• Observe how the spool moves against the spring force.
2. Select step 2 (dropdown menu 2) Proportional valve spool position changes orifice size.
• Observe how the changing orifice size, changes the flow through the valve.
3. Select step 3 (dropdown menu 3) Load pressure on the gear motor.
• Change the load pressure and note how the pressure drop across the spool changes.
• Observe how the flow changes as the load pressure changes.
4. Select step 4 (dropdown menu 4) Spool clearance
• Consider what pressures will exist on either side of each spool lands.
• Use the pressure drop information to predict leakage flow rates and paths.
5. Select step 5 (dropdown menu 5) O-ring seals
• Consider how the friction from an O-ring will affect seal movement.
• Operate the spool to see the effects on hysteresis from the seal.
6. Select step 6 (dropdown menu 6) Restricted volumes
• Consider how an orifice that restricts flow from a chamber will affect seal movement.
• Operate the spool to see how the trapped volume affects its speed of movement.
Experiment 1: Directional valves are simply open or closed. Proportional valves have notches that control the orifice size.
Question 1: How is flow controlled in a directional valve circuit?
Experiment 2: Flow is controlled by the size of a restriction and the pressure drop across it.
Question 2: Why does the flow change when the load pressure is changed?
Experiment 3: Every spool valve has a small leakage due to the clearances between the bore and spool.
Question 3: What factors will affect the leakage flow rate in each spool valve?