Difference Between Single Acting and Double Acting Pneumatic Cylinder

Difference Between Single Acting and Double Acting Pneumatic Cylinder

When it comes to linear pushing, pulling, and lifting forces, pneumatic cylinders are hard to beat. Their ability to turn compressed air into smooth automated motion powers all types of equipment and machinery. Providing smooth, reliable operation inside every pneumatic cylinder is a precision aluminum piston rod. Advances in aluminum materials, aluminum extrusions, and machining empower cylinder builders to keep improving performance and precision.

Pneumatic cylinders come in two main flavors: single acting and double acting. Knowing how these two cylinder types differ helps you choose the right one for any automation application. In this guide, we will compare the strengths and ideal uses of single and double acting cylinders. You will learn how to match cylinder capabilities to your force, speed, and control needs.

Single Acting vs Double Acting Pneumatic Cylinder

How Do They Work?

Single Acting Cylinders

They used compressed air to provide power in just one direction–typically on the outward stroke. A spring or some other external force returns the piston assembly on the backward stroke. They provide a one-way, single-shot linear motion.

In a single acting cylinder, compressed air enters the chamber behind the piston, pushing it forward until it reaches full extension. Once the air exhausts, the internal spring pushes the piston assembly back to the retracted starting point.

Double Acting Cylinders

They are powered by air pressure on both sides of the piston. This lets them extend and retract under air power in both stroke directions. Double acting provides smooth back-and-forth linear reciprocating motion.

They alternate air flow between chambers on either side of the piston. Air pressure in one chamber while exhausting the other makes the piston shuttle back and forth. The stroke direction depends on which chamber has air applied.

Force Generation

Single and double acting cylinders differ quite a bit when it comes to force capacity.

Single Acting Cylinders
They offer lower force output compared to double acting equivalents, typically up to 750 pounds of push force. They work well for basic inserting or pushing tasks that don’t require high pressures. Single acting cylinders are limited to applications that only require force on outward stroke. The return stroke relies on a spring or external mechanism.

Double Acting Cylinders
They can generate much higher push/pull forces, often over 10,000 pounds. They excel for pressing, clamping, or lifting applications needing significant reciprocating power. The double acting model provides equivalent force capability on the push and pull stroke. This makes them ideal for loads needing bidirectional power.

Speed and Stroke Length

Single Acting Cylinders

They have slower cycle rates because the spring limits retract speed. Their maximum stroke length is short too, often under 2 feet.

Double Acting Cylinders

They are capable of quick extend and retract strokes. Their cycle times are much faster for reciprocating motion. Stroke lengths over 10 feet are possible.

For fast or long linear motion travel, double acting cylinders are the winner. Single acting works for short repetitive strokes where speed isn’t critical.

Ideal Applications

Single Acting Cylinders

They tend to work best when you need:
Basic back-and-forth motion
The lower force under 750 pounds
Short repetitive strokes under 2 feet
Single shot motion
Applications do not need controlled retraction

Double Acting Cylinders

They are the way to go for:
High-force clamping or lifting needs
Automated reciprocating motion
Equal push and pull forces
Multi-position requirements
Longer strokes over 2 feet
Precise motion and speed control

For most automation tasks needing programmable back-and-forth motion, double acting takes the lead. But for simple in-and-out strokes, single acting is sufficient.

Proper Installation

To get the most out of any cylinder, follow manufacturer instructions for proper mounting. Use air filtration and lubrication for clean operation and long seal life. Minimize size loads on the piston rod whenever possible. Make sure the cylinder travels through its full intended stroke length and consider cushioning devices on stroke ends to prevent harsh stops. Keep seals clean and in good shape for optimal efficiency and fix any leaks immediately to maintain performance. Taking the time upfront prevents headaches down the road.

The Takeaway

Understanding how single and double-acting pneumatic cylinders differ allows you to pick the right one for your needs. Single-acting provides simple force for basic tasks. Double acting enables superior control for high-force, long-stroke applications. With the right cylinder design, pneumatics deliver cost-effective and versatile automated motion. Take time to choose a cylinder matched to your force, speed, and control requirements. If you want to learn more about cylinders and other aluminum products, feel free to reach us at YK-Longshun.

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