What are the main pneumatic components, and how do single and double-acting cylinders work?
Pneumatic components: the air supply, single-acting and double-acting cylinders, and the force a cylinder produces from pressure and area.
A CCEA GCSE Technology and Design answer on pneumatic components: the compressed-air supply, single-acting and double-acting cylinders and how each returns, and calculating the output force of a cylinder from pressure and piston area.
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What this dot point is asking
CCEA wants you to know the main pneumatic components - the compressed-air supply and the cylinders - the difference between a single-acting and a double-acting cylinder, and how to calculate the force a cylinder produces from pressure and area. Pneumatics uses compressed air to do useful work.
The answer
What pneumatics is
Pneumatic systems are clean, fast and safe (no electric shock), which is why they are used in factories, brakes and automatic doors.
The cylinder: where work is done
A cylinder (actuator) is the component that does the work. Compressed air pushes a piston along the cylinder, and the piston rod moves a load with a linear (reciprocating) motion.
A single-acting cylinder is simpler and uses less air but only works (pushes) one way; a double-acting cylinder is more powerful and controllable because it is driven both ways.
The force a cylinder produces
This shows that a larger piston or a higher pressure gives a larger force, which is how a small air supply can move heavy loads.
Worked example: cylinder force calculation
Examples in context
- Example 1. A bus door
- A double-acting cylinder pushes the door open and pulls it closed, working on both strokes under driver control - the reason a double-acting cylinder is chosen.
- Example 2. A clamp on a production line
- A single-acting cylinder pushes a clamp onto a workpiece while the air is on, and a spring releases it when the air is cut - simple and air-efficient.
- Example 3. A pneumatic press
- A large piston at high pressure gives a large force from , letting compressed air stamp or press parts.
Being able to distinguish the cylinder types and calculate the force from pressure and area lets you answer both the "explain the difference" and the calculation questions.
Try this
Q1. What does a pneumatic system use to create movement? [1 mark]
- Cue. Compressed air.
Q2. How is the piston returned in a single-acting cylinder? [1 mark]
- Cue. By a spring (when the air is released).
Q3. State the equation for the force produced by a cylinder. [1 mark]
- Cue. Force = pressure x area ().
Q4. A piston of area 0.003 m2 runs at 300000 Pa. Calculate the force. [2 marks]
- Cue. .
Q5. Give one advantage of a double-acting cylinder over a single-acting one. [1 mark]
- Cue. It is driven by air both ways, so it can do work (and be controlled) on both the out and return strokes.
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 the difference between a single-acting and a double-acting cylinder.Show worked answer →
A single-acting cylinder uses compressed air to push the piston out in one direction only (1), and a spring returns the piston when the air is released (1).
A double-acting cylinder uses compressed air to move the piston in both directions (1): air is fed to one side to extend it and to the other side to retract it, so it can do work on both the out and return strokes (1).
CCEA style4 marksA pneumatic cylinder has a piston of area 0.002 m2 and the air pressure is 500000 Pa. Calculate the force produced.Show worked answer →
Use force = pressure x area (1).
(1).
(1).
So the cylinder produces a force of 1000 N (1 kN) on the piston (1).
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Sources & how we know this
- CCEA GCSE Technology and Design specification — CCEA (2017)