3
4
Experiment 29
>
You will need: solar transporter, 140 more chain
links (29), four large sprocket wheels (11)
Instructions
Convert your solar transporter into a caterpillar track
vehicle, as shown in the pictures on these two pages.
You will just need chain links (29) and the large
sprocket wheels (11). You will have to remove the
cargo bed, because otherwise one side of its support
framework would interfere with the mounting of the
caterpillar track. Then take your model for a drive in
bright sunlight. What do you observe?
Results
At first glance, your caterpillar track vehicle drives
just like a vehicle with wheels. Under normal driving
conditions, there do not seem to be any significant
differences between vehicles with caterpillar tracks
and ones with wheels.
Driving Over an Obstacle
Caterpillar track vehicles show their strengths most
clearly when driving over uneven terrain. We will see
that in the next experiment.
Experiment 30
>
You will need: your solar-powered caterpillar
track vehicle, smooth, even, slightly down-sloping
surface (for example, a tilted drawing pad), a long
crayon or pencil
Instructions
Lay a long pencil or crayon across the path of your
caterpillar track vehicle to serve as an obstacle. Let
your vehicle get a running start and drive over the
obstacle, while you hold the pencil or crayon in place.
Pay close attention to what happens with the tracks
as they roll over it.
Results
As they roll over the pencil, the links of the chain wrap
themselves around the obstacle. So the chain adjusts
itself to fit the uneven ground. That improves the trac-
tion of the entire vehicle — it doesn’t slip the way a
car with wheels would do.
Driving Over Uneven Terrain
Now let’s see how your caterpillar track vehicle han-
dles when driving over a lot of obstacles, as it would
encounter if the terrain were uneven.
Experiment 31
>
You will need: your solar-powered caterpillar
track vehicle, several long crayons or pencils, bumpy,
slightly down-sloping ground
Instructions
Now lay several pencils on the surface at an angle, so
that when one track is on the ground the other will
be rolling over a pencil. Hold the pencils in place.
Observe how the tracks behave.
Results
The caterpillar tracks accommodate themselves
very well to the uneven surface and compensate
for bumps. If the obstacle is too large, however, the
vehicle gets stuck.
The inventors of the caterpillar track copied this prin-
ciple from nature: caterpillars also move similarly to
these tracks. That is why the treads are called caterpil-
lar tracks, and why the vehicles are known as caterpil-
lar track vehicles.
3. Now mount the four large sprocket wheels (11) on the ends of
the axles. Be sure that both sprocket wheels are positioned exactly
opposite each other, forming a straight line, on both sides of the
vehicle.
4. Make two chains of 70 chain links (29) each. Wrap the chains
around the large sprocket wheels. Check that everything moves
smoothly and easily.
25
