What’s a LIM?

The Linear Induction Motor

All three of our Rocket Cars were designed to be propelled by something called a Linear Induction Motor (LIM). This special type of motor is able to use a tall metal rail to create forward movement using electric current. This metal rail, called a “reaction rail” looks like an inverted T that fits underneath the engine. There is a small air gap between the reaction rail and the underside of the vehicle where the motor is located. In some vehicles like the Rohr, there are wheels which help keep the reaction rail in place relative to the rest of the vehicle, but those wheels do not drive the vehicle forward.

Here’s How You Make a LIM

Put electric current through a coil of wire and you’ll get a magnetic field. Now bring a piece of metal next to the coil and you’ll get an “opposing” magnetic field in the piece of metal. (It’s called “Lenz’s Law” if you really want to get into the science of it!) These opposing magnetic fields push against each other in a case of “like charges repel” (remember learning that in science class?), so the coil and the metal will push away from each other. A Linear Induction Motor is able to coordinate this repelling push, and turn it into forward motion.

Today, this technology is used in some trains in Tokyo, Japan and Guangzhou, China. A few automated people mover systems (like the subway trains you might find at an airport) also use this technology.

So Now Maybe You’re Thinking…

If you put electricity through a coil of wire that was constructed in just the right way, and you put a piece of aluminum on top of it, and if “like charges repel”, would the metal float above the coil of wire? Yes it would!! Check out the YouTube video below from Derek Muller’s educational science channel “Veritasium”. The video is a demonstration of electromagnetic induction, along with a description of how the scientific principle was discovered by 19th century English scientist Michael Faraday.

Click the back button on your browser to go back to the page you were on before.

Copyright © 2021, Pueblo Railway Foundation