The Kugelpanzer (literally translates as "spherical tank") was a prototype reconnaissance tank built by Nazi Germany during World War II. It was one of the most unusual armoured fighting vehicles ever built.
The only example of this Rollzeug (rolling vehicle) is in Russia as part of the Kubinka Tank Museum's collection of German armored vehicles. The Kugelpanzer is simply listed as Item #37 and is painted gloss gray. From fragmentary information, the drive has been removed from the vehicle and no metal samples are allowed to be taken from it.
This engineering sketch is a dedication to this weird machine, a piece with the overall goal, in our hopes, to promote awareness to an extremely little known mystery of the second great war
Link
Aluminum Foil
Doho, Di-cycle designs are an engineering oddity to be sure. It's hard to imagine situations where something like this could be truly advantageous, so I'd imagine it's some kind of very special purpose design, or just a proof of concept build.
The problem with Di, or even mono-cycles, is of course ... even if you do build up speed, slowing down is the hard part (with the trailing wheel, I would assume that it could pick up some speed, but breaking is still an issue) ~ And the relatively narrow track base (further exaggerated by the dihedral angle), to me, says it's a design where absolute 0 turning radius would be required.
Hm... I suppose one other possibility, could be a cheap artillery tractor?
Though in reality, there's already plenty of chassis capable of doing that, with much more proven technology.
Maybe they just be trollin :D