Toying with Cams

A timber, black and red exhibit table with matching information panel at the back in brown and white has two toy engines on the table top. The engines show the cam shaft and pistons, and are brightly coloured.
A timber, black and red exhibit table with matching information panel at the back in brown and white has two toy engines on the table top. The engines show the cam shaft and pistons, and are brightly coloured.

The shape of a cam disc influences the pattern and timing of how other things move.

How it works

A toy caterpillar and toy dog have rods attached to parts of their body, so different camshafts make them ‘jump’ or ‘wriggle’ in different ways.

Things to try or ask around the exhibit

  • Can the cams make the dog and the caterpillar move in different ways?
  • If you reverse the camshaft, does the animal move differently?

Background

If the cams are threaded off-centre onto the camshaft, they can raise or lower parts of the caterpillar and dog at different times. The cam shapes also change how the rods move the dog and caterpillar up and down.

Finding the science in your world

When camshafts are used in car engines, they open and close valves at different times. Cams are also used in automated toys to make objects appear and disappear at different rates and patterns.