Three-Wheeled Turret Car Looks Like It Should Be Orbiting Thunderdome

In a post-apocalyptic world, this is the hacker you want rebuilding society. He’s showing off a three-wheeled go-kart that pivots the cockpit as it steers. A hand crank mounted at the center of the vehicle pivots each of the three wheels in place, but keeps the driver facing forwards with a matching rotation. Hit up the video after the break to see it for yourself.

The real question here is, how did he pull this off? The watermark on the video shows that this was published by [wo583582429], a user on Douyin (the platform known as TikTok in the US). We plied our internet-fu but were unable to track down the user for more of the juicy details we crave. If you have a lead on more info, leave it in the comments below. For now, please join us in speculating on this build.

This is a pretty good closeup of one of the wheel assemblies. First question is how does the turning mechanism work? Since all three wheels and hub are smoothly coordinated it’s likely this is a planetary gearing setup where the inner ring has teeth that turn the rings around the tires themselves. However, we can see a spring suspension system which makes us doubt the lower ring surrounding the tire would stay engaged with a planetary gear. What do you think?

Trying to figure out how control and locomotion happens is even more of a head-scratcher. First guess is that it’s electric from the mere simplicity of the setup and this closeup shows what looks like a circuit breaker and wires connecting to batteries on either side of the suspension system. But where is the electric motor?

It’s a horrible image, but this is the best we can do for a view of the other side of the wheel assembly. There is a box that appears to be made from aluminum mounted to the wheel frame. After a few hundred times through the demo video we don’t think there’s a chain drive going down to the axle. It doesn’t look like there is a hub motor at play here either. We wondered if there was a second smaller wheel under the top of the frame to drive the main tire, but again, the suspension system would make this unfeasible and at points in the video there is clear daylight. Spend some time reviewing the Zapruder demo film below and when you figure all of this out, clue the rest of us in please!

It’s awesome seeing bootstrapped vehicles come to life. One of our favorites remains this all-terrain motorcycle that has no problem taking on stairs.

funny design

[via r/nextfuckinglevel]

31 thoughts on “Three-Wheeled Turret Car Looks Like It Should Be Orbiting Thunderdome

  1. At 28s, it looks like the lower circular structure on each wheel does have teeth, so probably planetary setup. For the suspension, it looks like the 4 vertical rods on each wheel assembly are fixed to the top of each assembly, and the planetary gear fixed to the bottom, stationary with respect to the body. The horizontal bar attached to each end of the axle appears to be able to slide up and down on those rods. Motor could be a friction drive mounted above, able to move up and down with the wheel but hidden from view.

    1. Hell, you’re right! In fact, it looks like they’re made from automotive flex plates that have been cut out. You know, the flex plate between the torque converter and the engine in a car with an automatic transmission.

  2. I think that the wheels can slide on the suspension shafts leaving the gear stationary. Something like a cross between the Morgan front suspension and a railway bogey.

    Hover-board motors in the wheel hubs would be one possible power source. I have seen them built in to all sorts of things, from sofas to motorcycles. (In fact I have driven both a sofa and a motorcycle so-equipped)

    1. I can see some blue and white packs that look to be batteries so you may be on the right track with hoverboard or ebike style hubmotors.
      I cant imagine where he found some that would like the weight of all the additional metal though, those must have been from something unique in itself…

  3. My bet is 3 vespa size hubmotors. The spring suspension also has an internal shock absorber that acts as a connecting rod (very likely under strain when turning at a dead stop). The top hub of the wheels is interesting and looks like some form of slip ring a motor combo. The bottom rings are indeed toothed however you can clearly see at around 23 seconds there is space between them and the main body. If I had to put money on it, they are electrically steered by the top hub electric motor. Likely something out of some industrial machines. The planetary gears theory doesn’t match up because he would move opposite to the wheels rotation, and the rate of turning would not be the same. That’s an awfully large ratio to reverse in such a small space.

    Looking again at the top hubs, you can see 2 sets of wiring to it, as well as something that looks like it could be an encoder on the “steering” shaft.

    1. That’s a good point on the gearing causing the turns to be opposite. However, if there is a smaller gear between each, then it would adjust the gear ratio and reverse the turn to match the rider.

      I also wondered about the top electric hub. You can see there are a couple small disks rising up from the main structure that almost look like insulator on old knob and tube systems.

      1. Yeah something like that. Thinking now, it’s likely out of some locally made forklift or pallet loader, the wheels definitely look industrial. For a hack like this though it may be a roll your own sort of deal where the hubs are actually built for a different size wheel but they popped them into the industrial looking things you see there.

        Pallet loader sounds really likely to me right now. It is in china so there could literally be hundreds of different sources.

    2. definitely hub motors with what appears to be disk brakes on the other side of the wheel, in the very beginning where he is rotating in place, you can pause it and see a wire on the right, and what appears to be a single piston caliper on a rotor(shiny) on the left.

  4. OK just 2 questions, first, does this remind anyone of a baby walker and second, where can I get one of these things, I mean NOW! Come on this guy is in China, start building them already!

  5. The wheels and rotating hubs are industrial equipment, probably a package deal, likely for some kind of material handling equipment. It’s similar, but probably smaller than, the rear wheel on 3-wheel forklifts you see on Lowe’s delivery trucks. But not powered in the original application. The hub motors that others have suggested are mounted against the actual wheels. Look at the rear wheel near the end of the video—the hub motors are darker than the original wheels, presumably because they’re newer.

    The pivot point where the wheels rotate on a vertical shaft: the motor is internal to the cylindrical end of the arm (coaxial with rotation). There’s an angular position sensor like an encoder or resolver, probably used in the original application to align the left and right wheels for steering (really a servomotor I guess). The clever part is the steering. The hand wheel turns a similar resolver or encoder, through a gearbox. There’s a horizontal cylinder below the steering wheel, and my guess is it’s a servomotor that is simply being used to encode a position signal for the pivot motors to drive/sync to. If the controller for them was originally designed to sync left/right, you could probably easily slave all three wheels to the steering position sensor. Now that I think about it, it would not be unlikely for that to be the original steering arrangement for the “donor” equipment.

  6. I wonder if those pulley things on the top of rotation hubs are part of the braking system… You can see a tube from the disk brake caliper running to the bottom of the hub, but how do you operate the brakes?

    1. If the hub motor theory is correct, the hub motor controller provides the braking. They can easily provide regenerative braking or just electric braking for the drive wheels.

      I think the theory of the round things being knob and tube style wiring insulators seems most probable. You can see a wire going to each one. The hacker(s) seems to be conscious of electrical safety, which is evident by the use of circuit breakers (white/light colored case) that you see near the batteries.

      If the wheels have disc brakes, I doubt they’re being used. It would be impractical to put a hydraulic system on this contraption, though I guess you could probably operate them without a master cylinder—but I don’t see anything suitable for doing so, like parts taken from a floor jack. I guess one final possibility is that they’re solenoid operated, and you apply power to disengage them. That would act like a parking brake after you stop, and I could see that being part of the original equipment design.

  7. While I do not think it is the case here, I wonder if the steering could be accomplished by varying the speed of the wheels? Then the connections to the chassis could be just something to transfer the weight with no direction control.

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