WHEEL AND AXLE/PULLEY
WHEEL-BELT SYSTEMS
Have you ever noticed how bicycle gears turn? The two gears are connected by a chain. When you push one
gear around, the other moves too.
A gear is just a wheel with teeth. There are many ways to connect wheels. Often, they are connected
with belts. Several connected wheels are called a wheel-belt system. You can make your own wheel-belt
system. You can make your own wheel-belt system with spools and rubber bands.
PROBLEM:
How can you make a wheel-belt system?
MATERIALS NEEDED
4 empty sewing spools
Board (Balsa wood)
4 screws
4 Rubber bands
A marker
Screwdrivers
STEPS
1.
2.
3.
4.
5.
Screw four screws into the board as shown in the figure (dimensions)
Make a dot on the rim of each spool with your marker
Put a spool in each of two nails
Place a rubber band around the 2 spools
5. Turn one spool. Watch the other spool turn too.
DISCOVERY PROBLEMS
A. How will the spools turn when connected in different ways? Notice the drawings below.
Each set spools starts with the left spool starts with the left spool. An arrow shows how each is turning.
Another spool set has a question mark. It is next to a dot on the spool rim. See how the spools are
connected.
Will the dot on the rim turn left or right? Make a record of what you think. Then use your wheel-belt
board to find out.
B. Look at the image below. How should the spools be connected to turn in these ways? How many
different connections can you think of? Make drawings of what you think. Then, use your wheel-belt
board to find out if they work.
C. What wheel-belt systems can you invent? Make up and trade some problems with friends. Fix your
board so you can make more spools.