In this blog post, I’ll explain step by step how a gyro drop actually comes to a stop, why it doesn’t use traditional friction brakes, and the principles behind eddy current brakes.
Gyro Drop Overview and the Limitations of Friction Brakes
A Gyro Drop is a ride where passengers board seats arranged in a circle, reach a high point (about the height of a 25-story apartment building), and then free-fall. Although the speed gradually decreases as it nears the ground, many people worry, “What if the brakes fail?” However, gyro drops generally do not use friction brakes—such as disc brakes—commonly found in cars or bicycles.
Using friction brakes presents three problems. First, kinetic energy is converted into heat and sound through friction, resulting in severe noise, vibration, and heat generation. Braking a heavy, high-speed ride requires a significant amount of energy to be dissipated as heat, which degrades the ride experience. Second, wear on components caused by friction shortens the brake’s lifespan, leading to frequent replacement and maintenance costs. Third, as wear progresses, the risk of failure increases and safety is compromised.
Non-friction Alternatives and the Selection of Eddy Currents
To avoid friction, non-friction brakes can be considered, and a method using electromagnets is one such idea. By placing permanent magnets in the seats and electromagnets on the pillars to utilize the repulsive force between like poles, the friction problem is solved. However, the electromagnet method has a critical drawback: it is vulnerable to power issues such as power outages.
Instead, the gyro drop utilizes the eddy current phenomenon. To understand eddy currents, it is helpful to know the relationship between electric current and magnetic fields (Ampère’s law), Lenz’s law (which states that induced currents resist changes), and Fleming’s left-hand rule for determining the directions of current, magnetic fields, and forces. The key point is that “a changing magnetic field induces a current within a conductor, and that current generates a magnetic field opposing the original change, thereby hindering motion.”
Taking a rotating conductor disc as an example, on the side where the magnet has passed, the downward magnetic field decreases, inducing a current in the direction that resists this change. Conversely, in the section approaching the magnet, the downward magnetic field increases, generating a current in the opposite direction to counteract it. When these induced currents flow inside the conductor, a force opposite to the direction of motion is generated according to Fleming’s left-hand rule, thereby decelerating the rotation.
In the case of a gyro drop, a horseshoe magnet (permanent magnet) is installed behind the seat, and metal plates (conductors) are arranged from the top of the column down to the drop section. As the seat descends and passes between the metal plates, eddy currents are induced within the plates, interacting with the magnet to generate a braking force.
Eddy current braking offers many advantages. It causes almost no wear on parts, making it virtually maintenance-free, and requires no power source, so there is no risk of failure during a power outage. Additionally, since the braking force is proportional to speed, it acts strongly when the ride is fast and weakly when it is slow, resulting in a gradual stop. In this regard, eddy current braking is more akin to a device that reduces speed, like a parachute, rather than a brake that stops the ride with a sudden jolt.
Just as you feel little resistance when walking with an umbrella but experience significant resistance when running, the higher the speed, the greater the braking force, allowing for a safe stop. Ultimately, it was not a massive mechanical apparatus that stopped the gyro drop, but a single physical principle involving magnets, metal plates, and eddy currents.
