How do valves control a pneumatic cylinder, and how is speed and direction managed?
Pneumatic control: 3/2 and 5/2 directional control valves, controlling single and double-acting cylinders, and speed control with flow-restriction valves.
A CCEA GCSE Technology and Design answer on pneumatic control: directional control valves (3/2 and 5/2), how they operate single and double-acting cylinders, methods of operating valves, and controlling cylinder speed with flow-restriction valves.
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What this dot point is asking
CCEA wants you to know how valves control a pneumatic cylinder: the 3/2 and 5/2 directional control valves, how they operate single and double-acting cylinders, the ways valves are operated, and how to control the speed of a cylinder. Valves are the "switches" of a pneumatic system.
The answer
Directional control valves
The number of ports tells you how many connections the valve has (supply, output(s) and exhaust(s)); the number of positions tells you how many ways it can switch.
Matching the valve to the cylinder
This is the core rule: 3/2 for single-acting, 5/2 for double-acting, because a double-acting cylinder needs air routed to two sides in turn.
How valves are operated
Pilot (air-operated) valves let one cylinder's movement trip the next, which is how automatic pneumatic sequences are built.
Controlling the speed
Worked example: building a simple control circuit
Examples in context
- Example 1. An automatic door
- A 5/2 valve drives a double-acting cylinder to open and close the door, with flow-control valves setting a gentle speed so it does not slam.
- Example 2. A clamping jig
- A push-button 3/2 valve drives a single-acting clamp cylinder; releasing the button lets the spring release the clamp - simple manual control.
- Example 3. A sequenced machine
- Pilot (air-operated) valves let one cylinder's motion trip the next valve, building an automatic pneumatic sequence without electronics.
Being able to match the valve to the cylinder and explain speed control lets you answer both the "explain the 5/2 valve" and "how is speed controlled" questions.
Try this
Q1. How many ports and positions does a 5/2 valve have? [1 mark]
- Cue. Five ports and two positions.
Q2. Which valve is used to control a single-acting cylinder? [1 mark]
- Cue. A 3/2 directional control valve.
Q3. Give two ways a control valve can be operated. [2 marks]
- Cue. Any two of: by hand (button/lever), mechanically (roller/plunger), by air (pilot), or by solenoid (electrical).
Q4. How is the speed of a pneumatic cylinder controlled? [2 marks]
- Cue. With a flow-restriction (flow-control) valve that limits the rate of air flow (preferably on the exhaust).
Q5. Why does a double-acting cylinder need a 5/2 valve? [2 marks]
- Cue. It needs air fed to both sides in turn to extend and retract, and a 5/2 valve can route air to either side.
Exam-style practice questions
Practice questions written in the style of CCEA exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
CCEA style4 marksExplain what a 5/2 directional control valve is and why it is used with a double-acting cylinder.Show worked answer →
A 5/2 valve has five ports and two positions (1). In one position it feeds air to one side of the cylinder and lets the other side exhaust; switching it reverses the air supply and exhaust (1).
A double-acting cylinder needs air fed to both sides in turn to extend and retract it (1), so a 5/2 valve, which can route air to either side, is the correct valve to control it (1).
CCEA style3 marksHow can the speed of a pneumatic cylinder be controlled?Show worked answer →
A flow-restriction (flow-control) valve is fitted that limits the rate at which air can flow (1). Restricting the air flowing out of (or into) the cylinder slows the piston (1).
Adjusting the valve changes how fast the cylinder extends or retracts, giving smooth, controlled movement rather than a sudden jerk (1).
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Sources & how we know this
- CCEA GCSE Technology and Design specification — CCEA (2017)