A piston of area 0.002\ m^2 operates at 500 kPa. Find the thrust. [2 marks]

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How do pneumatic components use compressed air to produce controlled motion?

Pneumatic components: single- and double-acting cylinders, control valves (3/2 and 5/2), and calculating the thrust of a cylinder.

A CCEA A-Level Technology and Design answer on pneumatic systems, single- and double-acting cylinders, 3/2 and 5/2 control valves, and calculating the output force (thrust) of a cylinder from air pressure and piston area.

Generated by Claude Opus 4.812 min answerUpdated 2026-06-16

Reviewed by: AI editorial process; not yet individually human-reviewed

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What this dot point is asking
The answer
Examples in context
Try this

What this dot point is asking

CCEA expects you to know the main pneumatic components (single- and double-acting cylinders, 3/2 and 5/2 control valves), to calculate the thrust of a cylinder from pressure and piston area, and to understand how compressed air produces controlled motion. The thrust calculation and the valve/cylinder pairing are common questions.

The answer

Cylinders

Cylinder thrust

Control valves

Worked example: sizing and controlling a clamping cylinder

Choosing a cylinder force and its valve

A clamp must press with at least 1 kN using a 600 kPa air supply, and must be powered both open and closed.

step Find the piston area needed

$F = pA$ , so $A = F/p = 1000/600000 = 1.67 \times 10^{-3}\ \text{m}^2$ . A 50 mm piston gives $A = \pi(0.050)^2/4 = 1.96 \times 10^{-3}\ \text{m}^2$ , which provides $F = 600000 \times 1.96\times10^{-3} \approx 1.18\ \text{kN}$ , comfortably above 1 kN.

step Choose the cylinder type

Because the clamp must be powered both ways (closed to grip, open to release with force), use a double-acting cylinder, not a spring-return single-acting one.

step Choose the valve

A 5/2 valve controls the double-acting cylinder, directing air to extend or retract; a flow-control valve sets the clamping speed. Sizing the piston from $F = pA$ and pairing the cylinder with the right valve is exactly the pneumatic reasoning CCEA expects.

Examples in context

Example 1. Bus door. A double-acting cylinder controlled by a 5/2 valve opens and closes the door under power both ways, the standard double-acting application.

Example 2. Factory clamp or ejector. A single-acting cylinder with a 3/2 valve clamps under air and releases on the spring, a simpler, cheaper choice where powered return is not needed.

Try this

Q1. State the formula for the thrust of a pneumatic cylinder. [1 mark]

Cue. $F = p \times A$ (pressure times piston area).

Q2. A piston of area $0.002\ \text{m}^2$ operates at 500 kPa. Find the thrust. [2 marks]

Cue. $F = 500000 \times 0.002 = 1000\ \text{N}$ (1 kN).

Q3. Which valve controls a double-acting cylinder, and why? [2 marks]

Cue. A 5/2 valve, because it feeds air to one side while exhausting the other and then switches, powering the piston in both directions.

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 20206 marksA double-acting cylinder has a piston of diameter 50 mm and operates at an air pressure of 600 kPa. Calculate the output thrust on the outstroke. Explain the difference between a single-acting and a double-acting cylinder.

Show worked answer →

Thrust (force) is pressure times piston area:

F = p \times A, \qquad A = \frac{\pi d^2}{4} = \frac{\pi (0.050)^2}{4} = 1.963 \times 10^{-3}\ \text{m}^2.

With $p = 600\ \text{kPa} = 600{,}000\ \text{Pa}$ :

F = 600{,}000 \times 1.963 \times 10^{-3} = 1178\ \text{N} \approx 1.18\ \text{kN}.

So the outstroke thrust is about 1.18 kN.

Single-acting cylinder: air pressure drives the piston one way only (the outstroke), and a spring (or external force) returns it. It uses one air port and is simpler, but the spring reduces the return force and the usable stroke.

Double-acting cylinder: air is applied to either side of the piston in turn, so it is powered in both directions (out and in), giving a controllable, powerful stroke each way. It uses two ports and a 5/2 valve.

Markers reward $F = pA$ with the correct area and consistent units (about 1.18 kN), and the single (spring return, one-way) vs double (powered both ways) distinction.

CCEA 20214 marksExplain the function of a 3/2 valve and a 5/2 valve in a pneumatic circuit.

Show worked answer →

Valves are named by ports/positions.

A 3/2 valve has 3 ports and 2 positions. It is used to control a single-acting cylinder: in one position it connects the air supply to the cylinder (extend), and in the other it connects the cylinder to exhaust so the spring returns the piston. It acts like an on/off switch for the air.

A 5/2 valve has 5 ports and 2 positions. It is used to control a double-acting cylinder: it directs air to one side of the piston while exhausting the other, then switches to reverse the flow, powering the piston out and in.

Markers want the ports/positions meaning, the 3/2 controlling a single-acting cylinder (on/off, spring return) and the 5/2 controlling a double-acting cylinder (powered both ways).

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Sources & how we know this

CCEA GCE Technology and Design specification — CCEA (2016)