Book 3, Question 21 · Video
Why Do Trucks Have So Many Wheels?
A loaded truck can weigh as much as many cars. Extra wheels spread that weight over more patches of pavement. More wheels share the weight, so the road does not crack!
Read the full answer →What Crafty Clover says in this video
Intro
Hey there, curious minds! I'm Crafty Clover! Let's discover something amazing. Why do trucks have so many wheels?
The Big Idea
A loaded truck can weigh as much as many cars. Extra wheels spread that weight over more patches of pavement. More wheels share the weight, so the road does not crack! If one tire fails, the others still carry the load. That is a safety spare built into the design.
Step 1
Step one: a heavy load. A truck's trailer is full of freight, and gravity pulls it all downward. That weight pushes down through the truck and into the road. Truck designers have to think about the roads and bridges too.
Step 2
Step two: many tires touch the road. Dual wheels and extra axles add lots more tires. Each tire touches the road with its own patch of rubber. It is like lying flat on snow instead of standing on one foot.
Step 3
Step three: the pressure drops, and the road survives. Pressure equals force divided by area. More tires mean more area, so each tire presses more gently on the road. That keeps the pavement from cracking.
A Closer Look
Let's take a closer look at a big truck! The cab is where the driver sits, and the trailer carries the freight. The drive axles power the truck. And dual tires are two wheels side by side. More tires, less pressure! Every part has a job when hauling big loads.
Quick Facts
Quick facts! A typical 18-wheeler has 18 wheels. Some mining trucks have tires taller than a grown-up! Weight limits protect bridges. And wide tires also help on soft dirt. Airplanes use many landing gear wheels for the same share-the-weight reason.
Think Like a Scientist
Now, think like a scientist! First, press just a fingertip into some clay. Then press with the back of a spoon. Which dent is deeper? That difference is pressure. Notice how pressure changes with size.
Outro
More wheels spread the weight so roads stay strong. Truck science rolls on! Crafty Clover can be found on Amazon Books, Google Bookstore, and Apple Books. Available for purchase or download! Bye for now!