Mechanisms That Make Things Move
A mechanism turns one movement into another: a push into a lift, a turn into a wobble, a small force into a big one. Levers, linkages, cams and cranks are the pieces a maker reaches for.
What a learner can do afterwards
- Say which mechanism is inside a moving toy or a pop-up card and say what it converts
- Explain what a cam does to a follower and why the cam's shape decides the movement
- Pick a mechanism for a stated job, such as making a puppet's arm wave
- Say why a linkage can reverse a direction of movement
1 · Read
Turn a key on a wind-up toy and its legs wobble. That's a mechanism: it turns one movement into another, a push into a lift. Levers, linkages, cams and cranks are the parts a maker reaches for.
A cam is a turning part that pushes a follower rod. As the cam turns about its turning point, the distance from that point to the edge touching the rod changes, so the rod rises and falls. A round cam can do this too when its turning point sits off to one side of the round shape. A raised part of the cam edge is called a lobe. A taller lobe reaches farther from the turning point, so it pushes its follower higher.
A linkage joins bars that push and pull each other, and it can even flip a direction. To wave a puppet arm you would pick a crank or a linkage, since a turning input suits a waving output. Say the full chain and what goes in and out.
Open a moving toy or a pop-up card and say which part is inside. Then say what goes in and what comes out, like turn in, lift out.
Push one end of a bar down and the bar turns about a fixed pivot between its two ends, so the other end goes up. That turn reverses the movement. A linkage joins bars at pivots like this. A forward push can turn a bar about its pivot, and the far end can then move down. The joined bars pass the movement on, but the pivot changes its direction.
Say which mechanism it is, then state which movement goes in and which comes out.
2 · Watch
Take it off screen
Where it sits
Learn first
Optional connections
This opens up
Where this leads
Jobs that lean on this skill. Follow one to see everything it is built on.
8 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.