How Does a Pneumatic Actuator Work?

One of the most common ways to generate linear motion for industrial applications is with an actuator. Actuators are devices that translate a source of static power into useful output motion. They can also be used to apply force.

Actuators are typically mechanical devices that take energy and convert it into various forms of motion. Some examples include blocking, clamping, or ejecting. Among the potential power sources available today, pneumatic actuators are one of the most straightforward, widely used, and cost-effective options.

Turning Energy Into Force

How do pneumatic actuators turn energy into force and motion? At their most basic, pneumatic actuators utilize compressed air acting on a piston inside a cylinder to move a load along a linear path. Unlike hydraulic alternatives, the operating fluid in a pneumatic actuator is simply air. So, leakage doesn’t drip and contaminate surrounding areas.

The most popular style of pneumatic actuator consists of a piston and rod moving inside a closed cylinder body. This actuator style can be sub-divided into two types based on the operating principle: single acting and double acting.

Single Acting Cylinders

Single-acting cylinders use one air port to allow compressed air to enter the cylinder. This then moves the piston to the desired position. An internal spring returns the piston to the “home” position when the air pressure is removed.

Double-acting Cylinders

Double-acting cylinders have an air port at each end and move the piston forward and back by alternating the port that receives pressurized air. This increases the overall air consumption but simplifies maintenance by removing extra components.

Turning Force Into Motion

In a typical application, the actuator body is connected to a support frame and the end of the rod is connected to the machine element that is to be moved. An on-off control valve is used to direct compressed air into the extended port while opening the retract port to atmosphere. The difference in pressure on the two sides of the piston results in a force equal to the pressure differential multiplied by the surface area of the piston.

If the load connected to the rod is less than the resultant force, the piston and rod will extend and move the machine element. Reversing the valving and the compressed air flow will cause the assembly to retract back to the “home” position.

Pneumatic actuators are at the working end of a fluid power system. Upstream of these units, which produce the visible work of moving a load, are compressors, filters, pressure regulators, lubricators, on-off control valves and flow controls. Connecting all these components together is a network of piping or tubing (either rigid or flexible), and fittings.

Pressure & Flow Requirements

Pressure and flow requirements of actuators in a system must be considered when selecting these upstream system components to ensure desired performance. Undersized upstream components can cause a pneumatic actuator to perform poorly, or even make it unable to move its load at all.

To get the right pneumatic components for your system, consider working with a specialist that can help you build the right machine for your needs. Contact our specialists by email or phone today to start evaluation.