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.
If you have an interest in tracked vehicles, we took a look at a few projects with tracks back in 2015.
With climbing structures like tank treads and rock climbing tires, you don’t want anything sticking out past the treads or tires.
You want them to contact the surfaces so the vehicle can pull itself over obstacles.
One way to have an engine powered track steering system is to have the engine drive the tracks through a differential, then have a CVT across the differential for steering.
An easier (and yes, worse) way is to drive through a differential, and put brakes on each track. Doesn’t turn in place, requires continuous operator intervention to track a straight (or constant-radius) path, and so on. It’s only benefit is that it’s ridiculously easy — a great way to get version 0.1 running while you keep an eye open for transmission-hacking components (CVTs, hydraulic motors, etc.).
You can also have a CVT on each wheel, but then you need bigger CVTs. If you have one across a differential you could just lock it 1:1 if your steering slips.
This is actually what I am planning. Most early tanks I looked at used something similar and yes essemtially it is a skid steer but simple is also important. Originally I was going half track for just that reason. Earlier this month I looked at replacing each electric motor with a 50cc gas engine. That gave me 6hp and I could steer by adjusting 2 throttles. With the differential I will apply enough braking on each side to slow one set of tracks enough to steer.
A braked differential is not just *worse*, it’s one of the *worst* choices, given what todays tech has to offer, even on a budget.
If you’re planning on doing the “modern” way of tank steering (an auxiliary motor introduces difference in track speed), a better approach for the auxiliary motor would be electrics, hydraulics just make everything messy, they offer little to no advantages with the loads intended for a personal vehicle. In an actual tank it makes sense, to use hydraulics, but here – probably not.
You can easily implement smooth turning with modern electronics which keep getting better and cheaper, hydraulics remain expensive.
Damn, 2 one kW motors and it won’t haul more than a kid?? Work on gearboxes!
Agreed, you would need those jackshafts/gearboxes for the gas engine anyway, the gas engine will have even less torque.
Electric with reduction would be a good idea.
Yup, a properly suped up powerwheels car can drive a grown man, and their motors are tiny. Those little gear boxes in them really help.
Actually no. Tbe reason for this is rhat the tank itaelf is very heavy. If you take alook at the project tou will see it is going to get a lot lighter. Plus, with almost 3x the power, gearing through sprockets and a differential amd this baby will go.
Oh and the kid weighs 105lbs, so he isn’t so small…
Still though, friction and everything, I see 2 overweight people going uphill on one 500W ebike… those mobility scooters they came from are heavy beasts and often cart around 400lb people, I still say you could get better out of them.
I probably can and will try
Those motors can haul way more than you think they can. And they’re fairly inefficient on low rpms. Get some gearboxes in there and let the motors run at higher rpm, that’ll make the thing accelerate and run fairly fast.
Ok, I’m convinced. I devised a change to keep the motors and skip the differential. I am waiting on some parts and LiPo batteries instead of the lead-acid monsters I have now and electric we go!
Agreed. There’s no reason 2kw shouldn’t be able to handle that load. Gearing is going to go a long way. Chain and sprockets on the cheap, gearboxes if you got the money.
It’s going to be #25 Chain, just like the kart. I am even salvaging rods from a set of dead inkjet printers (really beefy steel rods) to use as axles….
There is a reason tanks aren’t famous for excellent fuel economy (besides the weight of the vehicle). You lose energy to friction in all of those hinges and of course when steering you lose a fair bit to friction with the ground. That said, yes, some gearing would let you move more weight at the expense of top speed. Either way you slice it, this is not a mode of locomotion that is ever going to be terribly efficient.
(For reference I built my kids an electric tricycle using two surplus hoverboard wheels and it’ll haul me up a 10% grade and I had to extend it to not wheelie if the kids drove it, but it tops out at about 6mph so you can go too far on the more torque less speed continuum)
At one point I designed a 6×6 that of course would be way faster and way more efficient, but a tank is a tank :-)
You know I think I have a way to stay electric and get it moving better…..hmmmmm
I like it, nice work.
Thank you. It’s a bit of a dream for me. If anyone likes it enough please keep in mind it is entered in the Hackaday Prize, soooooo…
Keep going. The one that designs a “forehead slap” cheap and properly functional hobby tank tread is gonna be seeing $$$ especially if it can be scaled up. Start using a lab notebook, never rip out pages, show your work… this is nearly it, always carefully read Terms of Service.
I’m using this site as my notebook and my intent is to submit this for the Product prize as well. I wonder when DARPA is going to come a-calling :-). I am sticking to the rule that has me either 3D print specialized parts, but most components are off the shelf or are recycled stuff I have lying around. Even the tank’s chair right now was discarded from a cafeteria!
Now all of you folks who commented here should be heading over to the project page and liking the project so I can get closer to winning something to defray the costs and provide inspiration!
No need to build on of these when you have the real thing.We bought a Sherman tank at an estate sale.Just a little expensive to operate.