The most popular style of pneumatic actuator consists of a piston and rod moving inside a closed cylinder, designed to move in a straight line to deliver linear motion. This style of linear actuator is utilized in a variety of industrial sectors, factory automation and packaging, plus transportation and life science applications.
When looking to specify linear actuators there are two types of operating principle: single acting and double acting. We will explore these variations, typical applications plus advantages and disadvantages.
A single acting cylinder is one 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.
There are two types of single acting cylinder:
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.
Air pressure is applied alternatively 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.
To learn more about Parker’s Cylinders, click here.