Roller coasters; love them or hate them, there is no denying that they bring an abundance of fun. From fast accelerations to rapid inversions and winding layouts, they are a marvel of human engineering. But did you know magnets play a vital part in providing these thrills?
In this blog, we will discuss how magnets are used to accelerate rides to high speeds and how they can be used in braking systems to ensure the ride is brought to a safe and controlled stop.
Many modern-day roller coasters have now opted for an alternative way of providing energy to the trains of the coaster. Instead of using a traditional method of a chain lift, many rides feature a launch that can accelerate rides to higher speeds and is considered a more thrilling and exciting method of energy transfer.
There are a variety of methods used to launch roller coasters. Two renowned approaches are linear induction motors (LIM) and linear synchronist motors. (LSM)
These systems both use electromagnets to accelerate the trains down the track, but how do they work?
How The LIM System Works
Both LIM and LSM launch pairs of electromagnetic fins which are fixed along the launch section of the track. The electromagnets are installed on the top, or the side of the track. A small gap is left between the two fins allowing for a third fin attached to the train to run in the middle, or either side of the electromagnets.
For LIM systems, a current is directed to the pair of fins, therefore creating a magnetic field. The fin positioned on the train moves in between the pairs, thus entering the magnetic field. The moving plate produces a current known as an eddy current that is caused by moving the fins between the magnets.
This in term creates a magnetic field that opposes the original field and as a result, the fins are forced from the pairs, causing the train to accelerate along the track. The first coasters to feature this type of launch were Flight of Fear at both Kings Island and Kings Dominion.
How The LIM System Works
An LSM system utilizes a pair of fins connected to the train that are permanent rare-earth magnets. The magnetic field generated by the current in the fin pairs must correspond to that of the permanent magnets.
As the magnet approaches the set of fins, the magnetic fields attract one another and as the magnet passes each set of fins the two magnet fields repel, this causes the continued force in acceleration along the track.
The alternating magnetic field requires complex control systems which need to be controlled precisely. In comparison to LIMs, LSMs can also be used as a braking system as the process can be reversed. An example of an LSM-powered roller coaster is Tigris at Busch Gardens Tampa Bay in Florida.
Additional Uses of Magnets on Rides
Drop towers rely on two types of fundamental principles, electromagnetism, and pneumatics. The original design by Intamin features an electromagnetic system. The tower consists of a cylinder steel structure which is topped off with a machine room that houses the electric lift motors.
Once the gondola has reached the top of the tower, it is dropped into a freefall and is brought to a controlled stop by magnetic braking systems. At the bottom of the tower, there are two metal plates that run parallel to the set of rails. These align with permanent rare earth magnets that are mounted to the ride vehicles.
Each ride vehicle has 4 strips of magnets arranged in pairs to create thin gaps that are just wide enough for the plates to pass through. When a gondola drops down the tower the moving magnetic field induces enclosed loops of eddy currents. This generates its own temporary magnetic field that opposes the motion of the permeant magnets.
The result is then an electromagnetic drag force that acts on the ride vehicle opposite to the direction of travel. The repulsive force is like trying to push two magnets together with matching poles. The magnitude of the drag force is proportional to the magnetic current flowing through the plates. This determines the strength of the opposing magnetic field and the amount of current is proportional to the speed of the vehicle. This tells us the braking force will be highest when the permanent magnets are passing over the plates and the force will decrease linearly as the gondola loses speed.
The method of magnetic braking is often referred to as eddy current braking and is used all over the amusement industry, as it converts kinetic energy directly through the heat without the need for moving parts.
With magnets being used all across the amusement industry to help bring us the fastest and most exciting rides, the next time you visit a theme park make sure to look for these magnets and see them in action for yourselves!
Shop Electromagnets:
Electromagnets utilize electricity to provide a strong magnetic hold in both manual and automated holding and handing applications. The magnetic field is generated once an electrical current is applied, providing you with an instant, yet controlled, magnetic attraction and release of ferrous items.
Different Electromagnets Available:
Energise to Release Electromagnet with M6 Mounting Hole – 24V DC/100W – 50mm dia x 30mm thick – 88.2lbs Pull
Electromagnet with 6mm Mounting Hole – 12V DC/12W – 114.3mm x 63.5mm x 50.8mm thick – 882lbs Pull
Electromagnet with M5 Mounting Hole – 24V/8W – 40mm dia x 20mm thick – 55.13lbs Pull
These brakes tend to require less replacement than ordinary ride brakes, and are a cost saving as well as energy saving device. Often, magnets on a roller coaster are controlled through automated systems.