The axle stoppers make sure that the moving
parts don’t fall off the axle. Use as many
stoppers as you need!
Tip!
?
WHAT’S HAPPENING
Your stretched rubber band transfers the motion force from one pulley to the other. You’ve
found a way to bridge the gap between the pulleys. And the effort you use to turn one of the
pulleys is transferred to the other one. The pulley on the other side turns because it takes
less effort to move the pulley than to hold the rubber band in greater tension. The rubber
band grips well onto the plastic pulley wheel, stretches when the pulley turns, and pulls
itself back together (compresses) again immediately. Would that work with a loose string
as well?
3
At the back of the tree, push a pulley wheel
and an axle stopper onto each axle. This
should make it so that your pulley wheel
doesn’t slide off the axle when it moves.
4
Now stretch the rubber band over both
pulley wheels, and your rubber band belt
pulley system is ready!
3
4
On the cardboard sheet,
you’ll find two little
monkeys that you can hang
onto the belt pulley to make
it easier to see the elastic
moving. You can turn the
pulley wheels by hand, or fit
the crank handle onto the end
of the axle at the front and use it to
turn the pulleys.
17
Belt Pulley
