
508 Chapter 25 • Constructing Useful Stuff
There’s one last indirect pumping technique we would like to show. If you
press a wheel down on a soft rubber pipe until you close it, then move the wheel
forward along the pipe, any fluid inside will be pushed forward, too.You apply
this principle every day when you squeeze toothpaste out of a tube, and it’s also
used in medical procedures for regulating bloodflow. Figure 25.15 shows a pos-
sible setup that requires a larger diameter and much softer pipes than those sup-
plied with LEGO pneumatics.The pipe remains fixed in place, while the wheels
roll over it. Make your actual version more solid than this pr ...