system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: how does the elevator work in the St. Louis arch?

From pictures it looks like a Ferris wheel, but how does the entire contraption stay in balance not being a circle?
gpt
It isn't really an elevator.

The cars are attached together into a train, and then pulled up a track by a cable attached to a motor. The inside of each car can swing independently of the outside shell which allows the passengers to stay upright as it travels up the curved arch.