Inspired by this entry from David Szondy’s “Tales of Future Past” website, about an interwar magazine cover picturing an imagined giant submarine/battleship/tank, the “Submarine-Land Dreadnought”:
Got me to thinking . . . Every now in then in SF or in comic books, you see a giant mobile city on wheels or walking-legs. But, without antigravity technology, it’s probably impossible to make such a thing move at all. So what is the upper size limit? How big can a vehicle get and still move on land in Earth’s surface gravity?
The largest vehicle that exists at present is Bagger 288, which weighs about 13,500 tons and can travel at 0.6 km/h. I suspect that, if you wanted, you could build a lot bigger than that, perhaps by joining several machines like that together.
There were a couple of giant excavators compared in the last edition of Roadside America, but neither is operating anymore, and I gather they’re not as large as these German machines. Big Brutus and Big Muskie
Why would there be an upper limit? If you gang together n of some current vehicle and link their controls so they all start moving at the same time (put a little slack in the interconnects), what physical law would prevent the ‘joint’ vehicle from moving?
Just grow the vehicle horizontally and not vertically.
Before opening this thread, I thought you were going to say you had watched yesterday’s episode of Futurama. It featured a giant bus called the Land Titanic.
I’m not sure you can count those mining machines as “vehicles”, since they are not self-powered, but have to be wired into the electric grid to move. So that leaves the NASA Crawler-Transporter as the largest existing land vehicle.
Depends on the OP’s idea of a vehicle, I guess.
As to the largest possible in theory, I’d think the limits would involve the compressibility of the soil vs. the weight of the vehicle. If it has to travel over beach sand, plowed fields, or peat bogs it’ll be tougher than rock or lava flows. To keep the pressure per square foot down, you’d need big track pads. That increases weight, which needs a bigger, & heavier motor, and thus a bigger & heavier fuel tank.
Actually, the OP just said the biggest. So forget the giant tank/dreadnought and think of a vehicle made of plastics, aluminum, balsa wood, & fabric. Something like the materials used to build ultra-light aircraft, maybe?
Considering that the speeds of all the actual earth-movers listed above are “painfully slow” (Big Muskie moved at 0.1 miles/hour – that’s less that 9 feet per minute, or 1 3/4" per second ) , I’m guessing that an onslaught by such a Land Tank would be less than overwhelming. If one was approaching your house from a few miles away you could move everything out of your house before it got there. Sort of like an attacking glacier.
If you needed to, it would be pretty trivial to add a diesel-powered electric generator to one of those vehicles. They would be powered from the grid because that’s more efficient, not because that’s the only technical solution to the problem.
I don’t think the big excavators are the record-holders. Poking around online, I’m finding references to ore trains as long as 330 cars, and a loaded car can be as much as 140 tons. I don’t know if that 330-car train had cars that heavy, but if it did, that’d be over three times the weight of the TAKRAF, so there’s plenty of room for a fudge factor here. And of course the train is longer: They can easily get to two miles. Plus, of course, it’s much more clearly a “vehicle” than an excavator is.
And, in their desperation for a superweapon that could stave off their inevitable defeat, the Nazis thought even bigger: Landkreuzer P. 1000 Ratte - Wikipedia
As others have said, the real limitation is on pressure, not size. As long as the vehicle can continue to expand its width and the size of its contact with the ground, it can get as big as you want. The bigger it gets in this way, the more terrain becomes an issue… but you could imagine a very flexible mile-wide rubber vehicle slinking over the edge of the Grand Canyon and back up.
That’s where trains have an advantage, so I would second Chronos’ vote for trains. Even if the biggest so far is 330 cars, I suspect there’s no theoretical maximum for the largest possible train.
I would count a train as a series of linked vehicles rather than one vehicle.
I would say that to qualify as a single vehicle any component parts should be rigidly attached.
Whether it needs to be self powered is another matter but lack of self power doesn’t seem to be a valid reason to disqualify a vehicle since, as someone has already pointed out, it would be a fairly simple matter to add an electric generator to remove the objection.
I guess it depends on what you wanna consider land vehicle. A lot of big machines are really lots of many machines just being held together by beams the Space Shuttle Crawler is pretty damned big. Although if you want to talk biggest by mass in theory we would have to think about it. You need some form of locomotion. Tracks would have to be there. Axels would not support any big weight. Other than that I cannot see any reason anything else would hold you back.
You pretty much have to define how much connection different parts need to be considered one machine. Trains are connected but it usually takes more than a flip of a switch to disconnect them, I mean they are designed to be taken apart. I could take apart my car with the right tools. Like I said above a lot of big machines are just many small ones with beams connecting them. Think of the LHC many people consider it a huge machine. I think of it as many machines working in unison. Sidecar + Motocycle
Why? Is an articulated bus (i.e. that bends in the middle) one vehicle or two? If you call an articulated bus one vehicle, then why isn’t a 330 car train one vehicle?
