They were a novel pump. The Roots brothers invented the design in Civil War America and Roots pumps were used for moving air into mines, moving water where it needed to go, and even used to feed fresh air to air the combustion in blast furnaces. They had wooden rotors back then, simple two lobe designs that performed the work required of them in strong fashion. The Roots pump as a “blower” would take decades to make its way onto internal combustion but once that happened 80-90 years ago, we never looked back. To this day, Roots blowers are being more and more refined and highly developed.
But how do they work? You’ve seen the big shined up polished cases on show cars or the billet black cases on top fuel dragsters. What’s happening inside of said cases? That’s where this animation comes into play.
You’ll see exactly what’s happening inside the blower case and allow us to add a point or two. A lot blower does not pressurize the supercharger case. Screw blowers do that but the Roots makes its pressure in the manifold, not in the blower itself. The air is not taken into the middle and squashed between the rotors, it is scooped and moved to the outside, being effectively shoveled to the case and then sent out of the outlet in the bottom of the supercharger.
Here’s some history, some animation, and some goo stuff about Roots blowers!