Four wheels, two axles, a box, and a handle. That is all a wagon is. But with a wagon, you can easily carry a couple of friends or even give your dog a ride. When you use a wagon, wheels and axles are helping you. You can see the wheels. They are the round parts that roll over the ground. The axles are the rods that connect each pair of wheels. The wheels and axles turn together.
Putting wheels and axles on something makes it easier to move. It would be hard to pull a wagon without wheels. It would just drag over the ground. But wheels on axles roll along smoothly. Cars, trucks, and buses have wheel-and-axle parts, too.
Every day you are helped by other kinds of wheels – wheels that do not roll. A doorknob is a kind of wheel-and-axle machine. The knob is the wheel! You turn it to make the axle pull back the latch so the door can open.
A pencil sharpener has a wheel and axle, too. The handle is part of a wheel. When you turn the handle, it turns an axle that makes the other parts work.
Picture Credit : Google