How does a peristaltic pump work?

The pump hose is compressed successively by two pressing shoes assembled on a rotating wheel. The first shoe, by pressing the walls of the hose, will create a vacuum and attract the pumped liquid into the hose.

Once the pumped liquid has entered the hose, the second roller passes over the hose. This motion pushes the liquid toward the pump outlet. As the shoes are rotated, the hose section that was compressed begins to rebound to its nominal state, creating a vacuum that pulls fluid into the hose. 

When the shoe at the discharge side is detached from the hose, the opposing shoe is already compressed. This arrangement prevents any backflow. The pumped fluid is then successfully pulled in and pushed out due to the wheel rotation.