Lego vehicles don't typically escape the realm of electric power, but as we've seen before, you can build air-powered engines with the building blocks, and they can even do useful work. Getting them to power a car is a different story. In short, you have to carry your compressed air around with you, and that's easier said than done.
The little truck is powered by a three-cylinder engine, which fits nicely under the hood of the completed vehicle. This proved to be the best configuration tested. Power is sent to the rear axle via a one-speed gearbox with reverse. To prevent stress on the drivetrain components, there's a neat one-way clutch on the back of the engine that allows the truck to freewheel when the engine stops abruptly.
The entire thing is remote-controlled, and there's an entire ecosystem of Lego components to support this, which is pretty interesting. Likewise, it seems like there's something of a small economy of parts people use to make advanced pneumatic devices, like engines, out of Legos. If only I had this stuff as a kid.
The machine comes together nicely, but it seems like it's not until late into the vehicle's construction that our friend, uhh, Brick realizes just how poor the energy density of compressed air is, which is why it's a semi-truck hauling around two-liter bottles. To be clear, very highly compressed air can have an energy density (by volume) in the realm of lead-acid batteries, but that's at, like, scuba tank pressures. Two-liter bottles can hold up to a significant amount of pressure, but not that much.
With the two bottles, the little car has a fair amount of driving time for what it is, though. Also, it's just cool to see it actually working. The Lego truck has a little engine running on compressed air, carrying around its fuel with it. The only batteries involved are powering the various servos to enable remote control. We're all so used to seeing these things be powered by electricity, I guess seeing one powered by an energy source as unusual as compressed air is novel.
As usual, I just want to see more after this.
Got a tip? Email us at [email protected]