Rodless Air Cylinders 101: The Simple Solution for Complex Motion

Sometimes, your equipment needs a long linear stroke, but you don't have the space for a bulky actuator. That's a common engineering problem, and it's exactly why rodless air cylinders were invented. They revolutionized linear motion at the time, and these clever cylinders are still a go-to practical design solution.

It’s easier to visualize their unique advantages when you understand exactly how they work.

How Rodless Cylinders Save You Space

With a rodded cylinder, the rod extends outside the envelope to move the load, then retracts back inside. At full extension, the cylinder is essentially twice as long as the envelope. 

With a rodless cylinder, the piston inside the tube attaches to an external carriage. Usually the attachment is mechanical, but it can also be magnetic. Pressurizing one side of the piston forces it to move linearly through the tube, and the carriage follows along in the desired direction. The piston moves entirely within the envelope. With a cable style rodless cylinder, the piston moves in one direction and the carriage travels in the opposite direction.

Rodless air cylinders exert the same force in both directions. Since there's no long rod extending out, you get maximum stroke length with a minimal footprint.

Rodless Cylinder Advantages

Pneumatic actuator performance depends on the area of the piston and the amount of pressure applied. The key advantage for rodless cylinders is their length of travel versus envelope size.

• Long stroke length in confined spaces: Rodless cylinders allow more linear travel in a smaller space because there is no rod to extend. You don’t need to account for the rod, end caps, etc. in calculating required space.
• Better reliability: Rodless cylinders are more reliable than other options for long-stroke applications. With no external rod, there's no risk of bending or side loading, which are common issues with long-rodded cylinders under heavy use.
• Longer lifespan: The longer actuators last, the more you save on operations costs. Since rodless cylinders have fewer parts, they require minimal maintenance. Branham cable style rodless cylinders can be field-repaired with our easy-to-use repair kits.

Pneumatic Cylinder Types Explained

Branham has been designing and manufacturing both rodded and rodless pneumatic actuators for nearly half a century. We offer various styles of rodless cylinders, each designed for specific tasks requiring a long stroke in a limited space:

• DURATRK® cylinders incorporate advanced band-driven technology. A band attaches the internal piston to the external carriage for lengthwise travel and also seals the cylinder to prevent air leakage.
• MAGTEC® magnetic cylinders are a great choice for sanitary or harsh environments. Magnetic coupling reduces risk of contamination, which can prolong the life of any cylinder.
• PNEU-SA® cylinders.
• Cable style cylinders.
• Guided cable cylinders.
• Single-acting guided cylinders are designed for one-way operation such as horizontal or vertical lifting and articulation.
• Linear tension cable (LTC) cylinders are designed for tensioning where only a short stroke is required.

Rodless air cylinders continue to prove their value every day with their versatility and durability. However, it can be difficult to determine which style is best for your application. We’re here to help. Just contact us and we’ll help you figure it out.