I just saw this on the Binnsroad website: "L'Aero-Car" French-made clockwork aerial tram cars. One of these was shown on Ebay over a year ago, described as circa 1920's, 29 inches long, with a huge price that didn't sell. The 1920's claim sounds too early to me. It appears to require a free span of wire without intermediate supports. The drive pulley is relatively compact and unobtrusive compared to the bulky overhead motor on the newer MTH monorail. Following is a translation of the instructions.
Instructions on box, translated from French:
This toy, while metal, actuated by a clockwork movement, travels a distance of 25-30 meters on a wire stretched horizontally. For the aero-car back to its starting point, put the wire slightly sloping.
Its automatic disengaging allows it to also be the toy house; for a distance of 4 meters up the movement of 4 laps for a distance of 8 meters, the 6 rounds up to 25 to 30 meters up the maximum 12 rounds. Arrives at the end of the movement stroke, the automatic disengaging is triggered and the aero-car returns to its starting point. Do not go too hard movement to prevent the toy butt.
The aero-car is made up of 3 cars.
For operation of the toy, move the string below the small roller and the drive pulley located at the front, then place the cars on the wire, fix the aid of hooks located at the back of the wagons and go up the left movement in the distance to go.
Reassembly. Prayer observe the indications [illegible words] the number of towers up.