Nicholas-Joseph Cugnot Biography

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World of Invention on Nicholas-Joseph Cugnot

Cugnot is credited with developing the world's first self-propelled vehicle. Powered by a steam engine refined by Cugnot, his three-wheeled vehicle could carry four passengers and moved at a walking pace. Built in 1769 and first used the following year, Cugnot's vehicle was originally designed to haul heavy artillery pieces and should more properly be called a tractor and not a carriage.

Cugnot was born at Void, in the Meuse province of France. As a young man, he joined the French army and while in the service in Germany and Belgium, he invented a new kind of rifle for use by French troops. He was also encouraged to work on a steam-powered gun-carriage. Cugnot was aware of the improvements in steam power developed by Thomas Savery, an English inventor, and Denis Papin, a French physicist.

Cugnot added further improvements, which employed steam power to move pistons without condensation, greatly improving engine efficiency. His engine consisted of two, 13-inch (33 cm), 1.75-cubic-foot (50-liter) pistons connected by a rocking beam which were synchronized so that when atmospheric pressure forced one piston up, high pressure steam forced the other piston down. The reciprocating motion was transferred to the axle, where it produced the rotary motion that turned the wheel. This arrangement is considered to be the first successful device for converting reciprocating motion into rotary motion.

Cugnot's first carriage had serious limitations. Its three-wheel design, with the boiler well out in front, was inherently unstable, and the whole heavy boiler-drive-wheel mechanism had to be turned to steer the carriage. It carried no reserves of water or fuel and required that the driver stop periodically to refire the furnace and add water to the boiler.

Despite these obvious drawbacks, the French Minister of War, the Duc de Choiseul, was encouraged by Cugnot's first demonstration, and he commissioned Cugnot to build a second larger, more powerful, and faster vehicle. This second carriage was completed by Cugnot in 1771 at a cost of 20,000 livres. Unfortunately, de Choiseul fell from power before this second vehicle could be fully tested, and his successor showed no interest in Cugnot's steam gun-carriage. It sat in a military shed for 30 years until it was moved to the Conservatoire National des Arts et Métiers in Paris, where it has remained on exhibit ever since.

Cugnot was granted a pension by the War Ministry in 1779, and he moved to Brussels. The French revolutionaries eliminated Cugnot's pension in 1789, but it was restored during the Consulate by Napoleon and continued until Cugnot's death, which came on October 2, 1804, in Paris.