Properly Adjusted Air Cushion Solution Improves Actuator Productivity, Machine Reliability and Saves Money – Part Three

“A common goal throughout the business world is to increase productivity while reducing costs. This certainly applies to machine design, which means achieving the fastest possible cycle times. For pneumatic systems, this often requires running actuators as fast as possible without introducing excessive shock loads to the system.” This is the third post in series of blogs from Michael Guelker, product manager – pneumatic actuators, with Festo USA. 

Adjustable cushioning (right picture)Adjustable cushinioning

The throttling port (2) is adjustable, but constant along the whole length of the cushioning piston and has to be adjusted in accordance to the cylinder speed (1). For all different adjustments the cushioning length is constant.

Self-adjusting cushioning (top picture)

The throttle cross section (3) diminishes along the cushioning piston. The cushioning piston begins to work if the throttle cross section at the cushioning piston is smaller than the throttle cross section (1) at the speed control valve. That means that the effective cushioning length depends on the cylinder speed. Higher speed means higher kinetic energy and a longer cushioning length.

Principle of Self-Adjusting Air Cushion (left picture)

self adjusting air cushionThe throttle cross section at the beginning (1) defines the maximum allowable speed of the cylinder. It has to be as big as possible.   Because the cushioning pistons are very thin, rectangular cross sections are the best solution. They reach a big volume with a small depth.  The throttle cross section at the end of the cushioning (2) defines the minimum allowable speed where a cushioning effect can be reached. This throttle cross section has to be as small as possible. Cross sections with the shape of a V are the best solution, because they can be manufactured deeper.

In next week’s blog Mr. Guelker will finish his discussion and summarize the advantages and disadvantages of using air cushions.

If you would like to see more articles like the ones appearing in this series please email me at


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