01
DA: definition and engineering context
Double acting. Air pressure powers both extension and retraction.
The term belongs to the cylinder sizing context. Its exact limits can depend on the cited standard, catalog convention, unit system, reference state, and component configuration.
02
Why DA affects pneumatic selection
Requires directional control and consumes air in both directions.
- SA: Check spring force, fail position, and usable stroke.
- Cushioning: Match kinetic energy and cycle speed; cushioning does not replace external stopping when limits are exceeded.
- A: Use the rod-side annular area for retract force, not the full bore area.
- Bore: Force rises with the square of bore diameter.
03
How to evaluate DA in a catalog or replacement project
Read the value together with its unit, test basis, operating pressure, temperature, circuit state, and manufacturer definition.
For replacement work, compare the complete datasheet and drawing. A matching abbreviation or nominal size does not by itself prove functional or dimensional interchangeability.
- Single acting: Air powers one direction and a spring or external load returns the actuator.
- End-of-stroke cushioning: A method of reducing piston speed near an end cap.
- Effective piston area: Pressurized piston area used in the theoretical force calculation.
- Cylinder bore diameter: Inside diameter associated with piston area.
Selection checklist
What to verify before selection
- 01
Requires directional control and consumes air in both directions.
- 02
Check spring force, fail position, and usable stroke.
- 03
Match kinetic energy and cycle speed; cushioning does not replace external stopping when limits are exceeded.
- 04
Use the rod-side annular area for retract force, not the full bore area.
Application caution
Common mistakes
- Treating DA as a universal definition without checking the manufacturer or standard context
- Mixing gauge and absolute values, incompatible units, or different reference conditions in one comparison
- Selecting a component from the term or nominal value alone without checking the complete operating point and drawing
FAQ