Should I Use Wheels Or Tracks?

When it comes to dominating offroad performance, many people’s first thought is of tracked vehicles. Bulldozers, tanks and excavators all use treads, and manage to get around in difficult terrain without breaking a sweat. Today, we’re exploring just what makes tracked vehicles so capable, as well as their weaknesses.

It’s All About Ground Pressure

The various parts of a tank’s propulsion system.

Let’s first look at how tank tracks work. There are a huge variety of designs, with differences depending on application. Different trends have been followed over time, and designs for military use in combat differ from those used for low-speed construction machines, for example. But by looking at a basic tank track design, we can understand the basic theory. On tanks, the track or tread itself is usually made up of individual steel links that are connected together with hinges, though other machines may use rubber tracks instead. The tracks are wrapped around one or more drive wheels, often cogged, which directly pull on the track. On the bottom of the vehicle are the road wheels, which ride on top of the track where it lies on the ground.  The weight of the vehicle is carried through the road wheels and passed on to the tread, spreading out the load across a broader area. Outside of this, the track system may also have one or more idler wheels used to keep the track taught, as well as return rollers to guide the track back around without touching the road wheels.

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Autonomous 3D Rover With Tank Tracks Rules The Fields. Almost

Scope creep is a real pain in the real world, but for projects of passion it can have some interesting consequences. [rctestflight] was playing around with 3D printed rover gearboxes, which morphed into a 3D printed tank build.

[rctestflight]’s previous autonomous rover project had problems with the cheap geared motors, and he started experimenting with his own gearbox designs to use with lower RPM / Kv brushless drone motors. The tank came about because he wanted a simple vehicle to test his design. “Simple” went out the window pretty quickly and the final product was completely 3D printed except for the fasteners, axles, bearings, and electronics.

The tracks and gears are noisy, but it works quite well. On outdoor tests [rctestflight] did find that the tracks were prone to hooking on vines and branches, which in one case caused it to throw a track after the aluminium shaft bent. An Ardurover navigation system was added and with a 32 Ah battery was able to run autonomously for an entire day and there was surprisingly little wear on 3D printed gearbox and tracks afterward. All the STL files are up on Thingiverse, but [rctestflight] recommends waiting for an upcoming update because he discovered flaws in the design after filming the video after the break.

For a slightly more complex and expensive rover, check out our coverage of Perseverance, NASA’s MARS 2020 Rover. Continue reading “Autonomous 3D Rover With Tank Tracks Rules The Fields. Almost”

Massive 3D-Printed Ridable Tank Boggles The Mind

Anyone who has used an FDM 3D printer knows just how long the process can take, especially when you really start filling up the available print volume. Apparently [Ivan Miranda] has absolutely zero fear of insanely long print times, and is in the process of building a massive ridable tank (YouTube playlist of the whole build) that is almost completely 3D printed.

[Ivan] is no stranger to large prints, but this tank is on a different level altogether. The chassis, which is reinforced with aluminium and steel square tubing, took around 1200 hours to print and each of the wheels took 6 days! The rolling chassis with wheels and track weighs close to a 100 kg.  Having built a few smaller 3D printed tracked vehicles before, [Ivan] used a lot of that knowledge to design the latest monster.

Connecting the tracked section together has always proven challenging for [Ivan]. This time he used plastic fish tape (wire puller) for the pins, and blocked off the end holes with screws. The bogies (wheel sets) are also interesting, with 3D printed springs that sit parallel to the ground. Almost all the parts are printed in PLA, which can be quite brittle, so it would be interesting to see how it holds up.

[Ivan] has been working on this project since the start of 2019, and we can’t wait to see it completed. We’ve featured his signature red prints a few times, including a RC car that drives on the ceiling and a water jet drive. If you’re keen to build your own tank on the opposite side of the size spectrum, check out this tiny tank for your crawl space. Watch [Ivan] finish the rolling chassis after the break. Continue reading “Massive 3D-Printed Ridable Tank Boggles The Mind”

When The Going Gets Tough, These Wheels Transform To Tracks

When we want to build something to go where wheels could not, the typical solution is to use tracks. But the greater mobility comes with trade-offs: one example being tracked vehicles can’t go as fast as a wheeled counterpart. Information released by DARPA’s ground experimental vehicle technology (GXV-T) program showed what might come out of asking “why can’t we switch to tracks just when we need them?”

This ambitious goal to literally reinvent the wheel was tackled by Carnegie Mellon’s National Robotics Engineering Center. They delivered the “Reconfigurable Wheel-Track” (RWT) that can either roll like a wheel or travel on its tracks. A HMMWV serves as an appropriate demonstration chassis, where two or all four of its wheels were replaced by RWTs. In the video (embedded below) it is seen quickly transforming from one mode to another while moving. An obviously desirable feature that looks challenging to implement. This might not be as dramatic of a transformation as a walking robot that can roll up into a wheel but it has the advantage of being more immediately feasible for human-scale vehicles.

The RWT is not the only terrain mobility project in this DARPA announcement but this specific idea is one we would love to see scaled downed to become a 3D-printable robot module. And though our Hackaday Prize Robotics Module Challenge has already concluded, there are more challenges still to come. The other umbrella of GXV-T is “crew augmentation” giving operators better idea of what’s going around them. The projects there might inspire something you can submit to our upcoming Human-Computer Interface Challenge, check them out!

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Hackaday Prize Entry: GoKart Tank

There is probably something in all of us that yearns to drive a tank, just once. Most of us will probably never fulfill it, in fact, unless we work in farming or construction we’re unlikely to even drive a skid-steer vehicle of any type. But that doesn’t mean we can’t have a go at building one ourselves, as [samern] is doing with his Hackaday Prize entry.

The GoKart Tank has a chequered history, as a build that started as an internal combustion go-kart, became a half-track, and eventually the fully tracked electric vehicle we see today. It has a wooden frame, two 1KW electric scooter motors, and tracks made from IntraLox modular plastic industrial conveyor belt parts. This last choice is particularly interesting because even though it isn’t designed for use as a track it is designed for heavy-duty service and could offer a component source for other tracked vehicle projects.

What you see is a working tracked vehicle, but it is not without problems. The electric motors are only powerful enough to move a child, so there are plans to return it to internal combustion power. We can, however, see it working, as you can watch the video of it we’ve put below the break.

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