Latest Insights in the Evolving Digital World

Screen Doors and Linear Actuators

When I was a child, I remember running in and out of the house via our screen door. I remember the sound of the screen door’s hinges, or what I thought were its hinges, working, and the sound as it shut. My mother could hear

In what may have been an inevitable conclusion to my nearly incessant running in and out of the house, the hinge of the screen door came undone. Well, it was not the hinge, exactly, but was instead the little hydraulic piece that allowed the door to open and close without slamming back against the door jamb. We had it replaced, rather easily, and I went back to my in-and-out tendencies. The door lasted for years, I’m told. But what I did not know then, and what I have only recently learned, is that the little hydraulic piece that helps the door open and close as it is meant to is a kind of linear actuator.

I always thought linear actuators were some kind of complicated robot or something, or something straight out of science fiction. Instead, the linear actuator is a very commonplace piece of machinery that works to translate energy. That energy translation then makes motion possible. So, in the case of my screen door opener, air is compressed inside the tube. As the compressed air is condensed more and more the energy from the constricted air is transferred into the linear motion of the sliding tube that extends put from the hydraulic pump. As the tube extends the door opens, and as the door closes the tube contracts. Now that I know how a linear actuator functions, I look for them all over the place.