Pneumatic actuators convert compressed air energy into mechanical motion. They are the output devices of a pneumatic system — the components that actually do the physical work. While the pneumatic cylinder is the most familiar type, there are several actuator configurations each suited to different motion requirements. This guide covers the main types and when to use each.
Linear Actuators (Pneumatic Cylinders)
The standard pneumatic cylinder provides straight-line (linear) motion. A piston inside a cylindrical bore moves in and out as compressed air is directed to alternate sides. Linear actuators are used for pushing, pulling, clamping, lifting, pressing and conveying operations.
Within linear actuators there are further sub-types:
- Tie-rod cylinders (ISO 15552) — the standard workhorse of industrial automation. Four external tie rods hold the end caps and allow easy seal replacement. Available in bore sizes from 32mm to 320mm.
- Profile cylinders (ISO 21287) — compact aluminium profile body, lighter and shorter than tie-rod cylinders for equivalent stroke.
- Rodless cylinders — the piston moves inside a sealed slot; an external carriage couples to the piston magnetically or mechanically. Used where long strokes are needed in limited floor space.
- Guided cylinders — incorporate linear guide rails to prevent rotation and handle side loads. Used for pick-and-place and precision positioning.
Rotary Actuators
Rotary actuators convert air pressure into rotational motion over a defined angle, typically 90°, 180° or 270°. They are used to open and close valves, index rotary tables, flip components between orientations and operate butterfly dampers.
Rack-and-pinion actuators are the most common type. Two pistons drive a rack that rotates a central pinion shaft. They provide consistent torque throughout the rotation arc and are available in large bore sizes for high-torque applications.
Vane actuators use a rotating vane within a sector-shaped chamber. They are compact and light but limited to lower torques and shorter service life under heavy-duty cycling.
Grippers
Pneumatic grippers are specialised actuators designed to pick and hold parts. They are the fingers of robotic and pick-and-place automation. Types include:
- Parallel grippers — two jaws move symmetrically towards each other. The most common type for centring and holding components.
- Angular (pivot) grippers — jaws rotate on a pivot, giving a wider jaw opening for bulky components.
- Three-jaw grippers — for handling round or irregular parts requiring centring on three points.
Choosing the Right Actuator
Start with the motion type required: linear, rotary or gripping. Then determine:
- Force or torque required (with 25–50% safety margin)
- Stroke or rotation angle
- Speed requirement and cushioning needs
- Side load or moment loading (standard cylinders should not carry side loads — use guided versions)
- Environmental conditions (washdown, temperature, chemical exposure)
Parker manufactures an extensive range of pneumatic actuators including ISO 15552 cylinders, guided units, rodless cylinders and rotary actuators. Browse Parker pneumatic actuators at Captivair for technical specifications and ordering information.
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