You clamber into an open-air train cart that is then dragged 400 feet in the air. As you look down, knowing that you’re about to go hurtling toward the earth at eighty-plus miles per hour, it is natural to have a moment of doubt. Panicked thoughts may scurry across your mind: what exactly is keeping this cart moving? What are the chances of being flung off on the first turn? Am I really safe right now? Because the greatest fear is of the unknown, we want to put your amusement park terrors to rest by unpacking how roller coasters work.
A Slow Start
The first roller coaster built for an amusement park was created in 1884 by LaMarcus Thompson to offer a wholesome alternative to the saloons and brothels of the day. This coaster, Coney Island’s Switchback Gravity Railway, was powered by gravity. A cart was sent from a 50ft tall tower down a track to another tower at 6mph. Once it reached the other tower it was “switched” to a return track and the force of gravity carried it back again.
Gravity at Work
The world’s current fastest coaster, Formula Rossa at Ferrari World in Abu Dhabi, has a top speed over 140mph faster than the Switchback. Clearly, we are beyond gravity-power, right? Although there are a few tricks to get the coaster moving faster at the offset, roller coasters still largely rely on the power of gravity.
First, you are brought to the largest hill by mechanical means, either a lift chain or a hydraulic, electromagnetic, or pneumatic launch system. However, once you begin barreling down the first hill, the only thing that keeps you going is gravity. The higher one goes up a hill, the more potential energy is built up, and it’s because of the distance that gravity can pull the cart to Earth.
Once the cart drops, potential energy is released into kinetic energy that carries the cart through the rest of the track. Even when it hits new hills, the built-up momentum is enough to send it up the next hill and is partially renewed as it travels down the next one, as long as the next hill is not as tall as the first. By the time you reach the end of the track, the energy has run out and you slow to a stop.
Fun With Hydraulics
Even though gravity is the star of the show when it comes to how roller coasters work, it does get some help from hydraulics. Other than launching the cart, hydraulics are used to power the safety bar and braking system. Although coaster tracks are designed to have the cart slow to a stop by the end, brakes are still needed to stop the carts before they run into the car in front of them. If a roller coaster breaks down, it may be because of hydraulic cylinder failure, which is often fixed by replacing the hydraulic fluid.