This interesting steam railcar was designed by engineer Manfred von Herisau for the metric-gauge tramway lines that until the end of the '30s connected some pleasant places on Lake Constance.
Due to the very tight radii of curvature, a special articulation was necessary, so that the engine bogie and boiler rotated independently from the body of the car, which was supported by an adapted Prussian P8 bogie.
Naturally the RAEUDL did not approve this project because it was "too trivial".
In fact, according to RAEUDL, such a vehicle would have definitely disfigured even compared to the Doodlebugs of the Rio Grande Southern.
Herisau decided to build his own vehicle and he succeeded, but it was impossible for him to put it into operation because the RAEUDL decided to suppress the lines for economic reasons.
Ing. Herisau, overwhelmed by debts and remorse committed suicide by throwing himself into the lake and the locomotive was enameled to make room for a more useful chicken coop. Some local people claim to hear, on nights of full moon, the puffing of the plungers and to see a ghostly figure of a locomotive coming up from the lake and get lost in the moor, but mostly the local people explain the strange noises with the lapping of beer in the stomach of local good-timers or, at most, with lots of bad "stuff" ...
I would like to thank Erwin von Herisau for the great favor of having made available to me the original drawings of his grandfather in exchange for the phone number of someone I know in the area...