Lego train sets were introduced almost 50 years ago, and since then, one thing has been constant: the trains connected with magnets. While this is a supremely simple means of connecting locomotives to rolling stock, there is one big disadvantage. Building decouplers – devices that will separate one car from another – is difficult.
Now, with a clever combination of racks, gears, and wedges, trains can disassemble themselves. They can even do it with an Arduino.
This decoupler works by effectively wedging cars apart from each other. With a motor from an old Lego Technic set, a few gears, shafts, and a rack, a device can be constructed that fits between the rails of a track that raises into the undercarriage of rolling stock.
Because this rolling stock is moved around with a locomotive, all that’s needed to separate two halves of a train is to move the locomotive forward. Yes, it does mean that the connection with the weakest magnet is disengaged – not necessarily the connection you want to decouple. However, with only one car and a locomotive, there’s only one connection to break. Simple enough.
This Lego decoupler can be further improved with an Arduino, a few ultrasonic sensors, and an IR detector to make a fully automatic decoupling siding for a Lego train layout. You can see all this below operating with a full state machine that perpetually switches rolling stock behind a locomotive.
A great use for Legos.
Continue reading “Decoupling Lego Trains Automatically”
As a child, [Mike Chrisp] saw a film featuring one of the great narrow gauge English locomotives. While the story was inordinately heartening, as soon as he walked out of the theatre, [Mike] said to himself that he had to have one of these locomotives. Thus began a lifelong adventure in model engineering.
[Mike] builds model locomotives and other steam-powered means of motive power. Everything from five-inch gauge locomotives to small steam tractors is liable to come out of his small workshop, all built with the machining and engineering excellence only a lifetime of experience can provide.
As for what drives [Mike] to stay in his workshop for long hours, he says his shop is just a place to be, a place to tinker, and a place to simply think about things, even if his hands aren’t getting dirty. There’s something beautiful about that, even if [Mike] were to hide the products of his skill away from the world.
[Chris Thorpe] is a model railroading aficionado, and from his earliest memories he was infatuated with the narrow gauge locomotives that plied their odd steel tracks in northern Wales. Of course [Chris] went on to create model railroads, but kit manufacturers such as Airfix and Hornby didn’t take much interest in the small strange trains of the Ffestiniog railway.
The days where manufacturing plastic models meant paying tens of thousands of dollars in tooling for injection molds are slowly coming to an end thanks to 3D printing, so [Chris] thought it would be a great idea to create his own models of these small locomotives with 3D laser scanners and high quality 3D printers.
[Chris] started a kickstarter to fund a 3D laser scanning expedition to the workshop where the four oldest locomotives of the Ffestiniog railway were being reconditioned for their 150th anniversary. The 3D printed models he’s able to produce with his data have amazing quality; with a bit of paint and a few bits of brass, these models would fit right in to any model railway.
Even better than providing scale narrow gauge engines to model railway enthusiasts around the world is the fact that [Chris] has demonstrated the feasibility of using modern technology to recreate both famous and underappreciated technological relics in plastic for future generations. There’s a lot that can be done with a laser scanner in a railway or air museum or [Jay Leno]’s garage, so we’d love to see more 3D printed models of engineering achievements make their way onto Kickstarter.