Amusement parks are a staple of summer vacation, with over 375 million attendees annually in North America alone, according to the International Association of Amusement Parks and Attractions. (Worldwide annual attendance figures are around one billion!). And for many of us, the appeal of amusement parks can be summed up in two words: roller coasters. The taller/faster/twisty-er/more g-force-inducing, the better. While hydraulics, pneumatics, and chain-and-pulley systems are the fundamental driving mechanisms that provide these thrills, another technology has emerged over the last couple of decades and upped the thrill factor: linear motors.
Categorized as “launched” roller coasters, the first coasters to employ linear motors used linear induction motors, with the stator, or windings, embedded in the track, and conducting metal plates, or fins, attached to the cars. When current is applied to the windings, it creates a moving magnetic field in the track, which induces a magnetic field in the fins. The interaction of the magnetic fields propels the cars along the track.
Shortly after linear induction motors were first used in roller coasters, some manufacturers began using linear synchronous motors, which offer the advantages of higher efficiency and less heat generation than linear induction motors. With a linear synchronous motor, electromagnets are embedded in the track and permanent magnets are attached to the cars. The polarity of the electromagnets is switched rapidly, and the interaction between the electromagnets on the track and the permanent magnets on the cars moves the cars along the track. Switching the polarity of the magnets reverses the direction of the cars, which provides braking and allows the direction of the ride to be reversed.
So, why do some coaster builders use linear motors, when other technologies have been around for decades and are well-proven? The answer: dynamics. Or, in “rider-experience” jargon: intensity. Linear motors can reach top speeds of over 100 mph, but the key is that they can reach top speed must faster than other technologies are able to. That means higher g-forces and a higher intensity factor.
For manufacturers and park operators, launched coasters generally use less real estate than traditional coasters. This is because a launched coaster can produce high speed and acceleration without having to use a lift hill—the hill that you climb, and climb, and climb, knowing that the drop is coming any second. Although the suspense of climbing the hill is gone, the acceleration and speed more than makes up for the time, real estate, and cost of the lift hill. And linear motors are virtually maintenance free, since they have no moving parts.
If you’re an adrenaline junky and want to experience the intensity of a linear motor roller coaster for yourself, here are some options…