Rocket asks, "What if a rope broke?"
Raven looks at the cardboard model. "What do you notice holds the car?"
"Only the string," Rocket says. He looks worried.
Nova glows two rails. "Would you like a hint? Real cars have brakes that grab."
A real elevator hangs from several strong steel ropes, not one.
The car rides on guide rails, like a train on a track.
If the car ever moves too fast, a speed watcher trips.
Then safety brakes grip the guide rails and stop the car.
Elevators are built so a broken rope does not drop the car.
Long ago, an inventor showed off a safety brake.
He stood on a lifted platform in front of a crowd.
A helper cut the rope on purpose.
The platform fell only a few inches and stopped.
A spring in his brake caught toothed bars on the shaft.
| Sentence | True or false? |
|---|---|
| Safety brakes grip the guide rails. | ? |
| A real elevator hangs from one thin rope. | ? |
| The counterweight moves the opposite way from the car. | ? |
| Guide rails keep the car in its lane. | ? |
Tomorrow is your Machine Show!
Pick one machine from this course.
A zipper, a faucet, a switch, a pen or the elevator.
Practice telling how it works in your own words.
You explained the elevator and its safety parts. Fantastic!
Tomorrow is Machine Day: your Machine Show!