Nicolas Joseph cugnot demonstrated his fardier à vapeur, (steam dray) an experimental steam driven artillery tractor, in 1770 and 1771. But his design proved to be impractical, his invention was not developed in his natice france.
The design of the Cugnot Steam Trolley (Jonathan Holguinisburg) (1769)
Cugnot was one of the first to employ successfully a device for converting the reciprocating motion of a steam piston into rotary motion by means of a ratchet arrangement. The following year, a full-size version of the fardier à vapeur was built, specified to be able to carry 4 tons and cover 7.8 km or 4.8 miles in one hour, a performance it never achieved in practice. The vehicle, which weighed about 2.5 tonnes tare, had two wheels at the rear and one in the front where the horses would normally have been; this front wheel supported the steam boiler and driving mechanism. The power unit was articulated to the "trailer" and steered from there by means of a double handle arrangement. One source states that it seated four passengers and moved at a speed of 2.25 miles per hour.
Cugnot's steam wagon, the second (1771) version
The boiler is fixed infront of the vehicle and two cylinders were used. Look here how the steem engine works. According to this principle this vehicle was manufactured.
Steam Engine Operation
The following diagram shows the major components of a piston steam engine. This sort of engine would be typical in a steam locomotive. The engine shown is a double-acting steam engine because the valve allows high-pressure steam to act alternately on both faces of the piston. The following animation shows the engine in action. You can see that the slide valve is in charge of letting the high-pressure steam into either side of the cylinder. The control rod for the valve is usually hooked into a linkage attached to the cross-head, so that the motion of the cross-head slides the valve as well. (On a steam locomotive, this linkage also allows the engineer to put the train into reverse.) You can see in this diagram that the exhaust steam simply vents out into the air.
The vehicle was reported to have been very unstable due to poor weight distribution - which would have been a serious disadvantage seeing that it was intended that the fardier should be able to traverse rough terrain and climb steep hills. In 1771, the second vehicle is said to have gone out of control and knocked down part of the Arsenal wall, (the first known 'automobile' accident?); however according to Georges Ageon, the earliest mention of this occurrence dates from 1801 and it does not feature in contemporary accounts. Boiler performance was also particularly poor, even by the standards of the day, with the fire needing to be relit and steam raised again every quarter of an hour or so, considerably reducing overall speed.
