Cam Wave

A row of vertical green pipes in a wave formation, sit under a overhead walkway. They both sit within a large foyer.

The turning motion of cams can be transferred into an up and down motion to move machinery.

How it works

Stand and watch the green rods move in patterns until they come to a straight line.

Things to try or ask around the exhibit

  • Is there a constant wave pattern, or does the wave slowly change over time?
  • What's moving each green rod up and down?
  • What do you notice about the way that each white disc turns?


Each green rod moves up and down to create the illusion of a wave that seems to move sideways. Each green rod is raised and lowered by a pair of white discs at the back. These white discs are called cams and they change the turning motion of the cam disc into the more 'up and down' motion of the green rods.

Each green rod's pair of cams are offset, so they turn at different speeds and raise and lower each green rod at different speeds. A rod moves up and down a long way if the peaks from each wave reach the rod at the same time. If the peak of one wave reaches a rod at the same time as the trough of the other wave, the two waves cancel one another out .

Finding the science in your world

Machinery cams are usually driven by an engine's motor. Cams can be circular or may be different shapes with ‘bumps’ to push and move machinery parts in different patterned movements, similar to the way the exhibit's cams raise and lower the green rods to create different speeds and patterns of movement.