When toys get overly complicated.
Remember when Legos used to be pretty much a blank canvass than any kid with an imagination could go crazy with? I mean, it was all about making things from different pieces, and the fun was in creating anything that you could think of. Being such a huge toy company, Lego has always been expanding its lineup of products, ranging from full-blown movie tie-ups and even licensed cars. The Technic line has always been the more complex yet utterly satisfying sets to build, and with things like lights, transmissions, and even electricity, these top-tier Lego "toys" are far from their humble beginnings. But boy do they satisfy the inner gearhead at times.
Gallery: See How A CVT Works, Using Legos
As with anything on YouTube, if you can think of it, there will be a channel for it, and Sariel's Lego Workshop focuses on some very neat stuff. In this video, he takes us through a continuously variable transmission (CVT), all completely built out of lego pieces and a power source. It's incredibly similar to what we have in modern cars, and the pulley system with the shafts and the belt are executed in their own Lego way. The ratios are simulated by the belt that interacts with the cones that run parallel but are oriented opposite of each other. There are no fixed ratios, it's clutch-less, and all you get is maximum or minimum, and all you have to do is move the mechanism forward or back to speed up or slow down.
Now it isn't perfect, and as Sariel points out in the video, Lego's CVT system is effective at low loads and low resistance. The belt travels along the cones so smoothly that the band tends to slip out of "gear" when encountering an obstacle or incline.
Sariel also mentions that this wouldn't happen if Lego made some rubber cones for higher friction to keep the belt in place, or maybe even a step further by creating toothed cones and belts. In any case, it's still very satisfying to watch.