Before presenting the features of this important class of fluid actuators, it seems useful to describe how I originally became involved.
About 1970, I first met John Yarlott & visited his company, Trish Energetics in Harvard, Massachusetts. There, John demonstrated for me his new Ampflex actuators [further described in the links below] as well as several controlled devices which commercially employed them to useful purpose.
Then shortly after this visit, I happened to be sketching the design for a small 3-cylinder radial air motor to be built for demonstration to graduate students in my MIT subject "Dynamics & Control of Rotating Machine Systems". But to my great surprise, instead of pistons & cylinders, I found myself drawing 3 Yarlott actuators connected flexurally to a central distributor hub & disposed 120 degrees apart ! Thus was born the Dynacycle Air Motor & shortly after, the Dynacycle Corporation, which ultimately acquired Trish Energetics.
The rest of this story is best told via the links below.