Choosing between a single-acting and double-acting pneumatic cylinder comes down to how the application needs the piston to move. A single-acting cylinder uses compressed air to move in one direction and relies on a spring or external force to return. A double-acting cylinder uses compressed air for both extension and retraction, giving it powered motion in both directions.
Both cylinder types convert compressed air into linear motion, but they are used in different situations. Single-acting cylinders are often a good fit for simpler, one-direction tasks like clamping, positioning, marking, stroking, and light assembly. Double-acting cylinders are better suited for applications that need more control, repeatable movement, or force in both directions.
This article compares single-acting and double-acting pneumatic cylinders so you can better understand how each works, where each is used, and what to consider when selecting the right cylinder for your application.
The main difference between single-acting and double-acting pneumatic cylinders is how compressed air moves the piston. A single-acting pneumatic cylinder uses compressed air to move the piston in one direction, then relies on a spring, gravity, load weight, or another external force to return it. A double-acting pneumatic cylinder uses compressed air to move the piston in both directions, providing powered extension and retraction.
Because of that difference, single-acting cylinders are typically used for simpler applications where work is only needed in one direction. Double-acting cylinders are used when the application requires more control, repeatable movement, or force in both directions.
In general, single-acting cylinders are simpler and use less air, while double-acting cylinders offer more control and flexibility. The right choice depends on the required motion, force, stroke length, cycle speed, air usage, mounting style, and return method.
| Factor | Single-Acting Cylinder | Double-Acting Cylinder |
|---|---|---|
| Air ports | One air port | Two air ports |
| Motion | Powered movement in one direction | Powered movement in both directions |
| Return method | Spring, gravity, load weight, or another external force | Compressed air |
| Air usage | Uses air for one direction of travel | Uses air for both extension and retraction |
| Best fit | Simple applications where work is needed in one direction | Applications that need force, control, or repeatable motion in both directions |
| Common uses | Clamping, positioning, marking, stroking, light assembly, and simple push or lift tasks | Opening and closing mechanisms, controlled movement, guided motion, larger stroke applications, and tasks requiring force in both directions |
When looking to specify linear actuators, there are two types of operating principles: single acting and double acting. We will explore these variations, typical applications, and advantages and disadvantages.
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A single acting cylinder: Parker's P1P Series |
A single acting pneumatic cylinder is a cylinder where the thrust or output force is developed in only one direction.
The piston is returned by a fitted spring, or by some other external means such as a weight, mechanical movement, gravity, or an external spring. They have a single port to allow compressed air to enter the cylinder to move the piston to the desired position.
Single acting cylinders are typically used for applications where work is done only in one direction, such as clamping, positioning, marking, stroking and light assembly operations.
There are two types of single acting cylinders:
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Push-Type Single-Acting Cylinders The application of air pressure produces a thrust, thus ‘pushing’ the piston. |
Pull-Type Single-Acting Cylinders The application of air pressure produces a thrust, thus ‘pulling’ the piston. |
Simple design
Compact size
Reduction in valve and piping costs
Air consumption is halved compared with the equivalent sized double acting cylinder
Return spring side of the cylinder is vented to atmosphere – may allow the ingress of foreign matter, which may lead to malfunctioning and reducing the life of the cylinder.
Spring operation with extended cylinder life can become inconsistent and provide uncertain end of stroke positions.
Bore size and stroke of the cylinder is restricted due to limitations of the spring size and force.
A slight reduction of thrust due to the opposing spring force.
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A double acting cylinder: Parker's P1F Series |
A double acting pneumatic cylinder is one where the thrust, or output force, is developed in both extending and retracting directions.
Double acting cylinders have a port at each end and move the piston forward and back by alternating the port that receives the high-pressure air, necessary when a load must be moved in both directions such as opening and closing a gate.
Double acting cylinders are the most widely used of all designs of linear actuators. They account for approximately 95% of all cylinders used in pneumatic control circuits.
| Air pressure is applied alternately to the opposite ends of the piston. Application of air pressure produces a thrust in the positive (push) stroke, and a thrust in the negative (pull) stroke. |
Double acting pneumatic cylinders are typically used in all applications where the thrusts and stroke lengths required are in excess of those available from single acting cylinders.
Small double acting cylinders are also used for applications where positive end-of-stroke positions are required for both strokes.
Generally, ISO standards are based on the design of double acting cylinders.
A more extensive range of double acting cylinders than for single acting cylinders, giving many more options of bore and stroke sizes.
Many variations are available on the basic double acting cylinder design.
Cylinders cannot be simply held in a mid-position as the cylinders do not have a mechanism to stay in that position.
Air is a compressible medium – if a pneumatic cylinder is to be used as a feed cylinder, it has to be coupled to a hydraulic slave cylinder to give a constant feed.
Long stroke cylinders need adequate guiding of the piston rod to work properly.
Choosing the right pneumatic cylinder starts with understanding what the cylinder needs to do in the application. A single-acting cylinder may be the better fit when motion is only required in one direction and a spring, gravity, load weight, or external force can return the piston. A double-acting cylinder is usually the better choice when the application needs powered movement in both directions, more control, or more consistent cycling.
Important selection factors include the required force, stroke length, cycle speed, available air pressure, mounting style, space constraints, load direction, and whether the cylinder needs to extend, retract, or control motion in both directions. Air consumption may also matter, especially in systems where efficiency and compressed air costs are a concern.
In general, single-acting cylinders are often used for simpler push, pull, lift, clamp, or position tasks. Double-acting cylinders are better suited for applications that require repeatable motion, controlled extension and retraction, longer strokes, or force in both directions.
Need help selecting the right pneumatic cylinder? MCE can help review your application requirements and identify a pneumatic solution based on motion, force, stroke, mounting, control, and compressed air needs. Contact MCE >>