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British Industrial History

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Nicholas Joseph Cugnot

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1. 1771 Fardier at the Musée des arts et Métiers, 2019
2.
3.
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6. Showing the chain attached to the bottom of the forked piston rod, which pull the torque arm downwards, turning the front wheel via the ratchet
7. Showing how the cylinder is bolted to the support frame
8. A view of the underside of the piston from below the RH cylinder
9. Four-way valve, operating gear, and spring. The 'mudguard' deflects water and steam exhausting from the valve
10. Four-way valve and manifold
11. Valve operating chain. Also note the rocker arm at the bottom of the picture, which interconnects the two piston rods via chains
12. Valve operating lever and tappets bolted to piston rod
13. Close-up of tappet and roller
14. Steam isolating/throttle valve on top of boiler. Note threaded pipe connector
15. Steering gear
16. Showing steering sector from below, and roller on right hand side which transfers weight of vehicle body to the steerable engine/boiler sub-frame
17. Roller on left hand side
18. RHS, looking toward rear, indicating complexity of forged wrought iron sub-frame, and treads on iron tyre segments
19. Steering pivot and rocker arm to connect piston rods via chains
20. 1770.
21. 1769
22. 1769
23. 1769
24. 1770.
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Background

Nicolas-Joseph Cugnot (26 February 1725 – 2 October 1804) was a French inventor. He built two self-propelled steam carriages, one of which is preserved at the Musée des arts et Métiers in Paris. He was almost certainly the first to construct a full-size working steam-powered vehicle.

It has been recorded that Ferdinand Verbiest, a member of a Jesuit mission in China, built a 'steam car', c.1672. It was probably a model. An account by the Abbé Huc described the vehicle as being equipped with an aeolipile whose steam jet was directed 'upon a wheel to which four wings were attached; the motion thus produced was communicated by gearing to the wheel of the car.'[1].

As described, Verbiest's steam turbine-powered vehicle would have been an interesting experiment, with no prospect of practical utility. In contrast, Cugnot's surviving machine was designed and constructed with serious intent. Its engine was remarkably ingenious and of advanced design and construction, but the boiler design left much to be desired. For the time, Cugnot's machine was truly remarkable.

Biography and History

Cugnot was born in Void, Lorraine, (now department of Meuse), France. He trained as a military engineer. He experimented with working models of steam-engine-powered vehicles for the French Army, intended for transporting cannon, starting in 1765.

Cugnot ingeniously converted the reciprocating motion of steam pistons into rotary motion, using a ratchet arrangement. A small version of his three-wheeled 'fardier à vapeur' ran in 1769. (A fardier was a strongly-built two-wheeled horse-drawn cart for transporting very heavy equipment such as cannon barrels).

The following year, a full-size version of the 'fardier à vapeur' was built, specified to be able to carry 4 tons and cover 2 lieues (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 a single driving wheel at the front; this front wheel supported the steam boiler and driving mechanism. The power unit was articulated to the "trailer".

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, possibly the first known automobile accident. 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 re-lit and steam raised again every quarter of an hour or so, considerably reducing overall speed.

After running a small number of trials variously described as being between Paris and Vincennes and at Meudon, the project was abandoned and the French Army's experiment with mechanical vehicles came to an end.

In 1772, King Louis XV granted Cugnot a pension of 600 livres a year for his innovative work and the experiment was judged interesting enough for the fardier to be kept at the Arsenal until transferred to the Conservatoire National des Arts et Métiers in 1800, where it can still be seen today.

With the French Revolution, Cugnot's pension was withdrawn in 1789, and the inventor went into exile in Brussels, where he lived in poverty. Shortly before his death, he was invited back to France by Napoleon Bonaparte and Nicolas-Joseph Cugnot returned to Paris, where he died on October 2, 1804.

The Surviving Fardier

The surviving fardier à vapeur is on display in the Musée des arts et Métiers. See photos. The museum give the date of construction as 1771 [2].

Cugnot's achievement deserves wider recognition. Prior to the construction of his machines, steam engines were large, immobile, and produced only reciprocating motion. They worked on the atmospheric principle, requiring a condenser. Cugnot boldly embarked on the development of a machine which produced rotary motion, worked with direct steam pressure, needed no condenser, and at the same time was sufficiently compact to propel itself and its burden. This required the introduction of a number of ingenious and novel mechanisms, demanding a degree of precision in their manufacture. It is true that the design of the boiler was seriously flawed with respect to feeding and firing, but no doubt Cugnot would have addressed these problems in time. Presumably Cugnot was also the first to a introduce the tyre tread!

The reciprocating motion of the pistons was converted to rotary motion at the driving wheel by means of ratchets and pawls. Two cylinders were needed to make the engine self-acting. Steam to and from the cylinders was admitted and exhausted through a single four-way valve (a semi-rotary cock with four ports). The valve was rotated by pitch chains, activated by tappets on the piston rods.

The action of the pawls and ratchets could be reversed, effectively at the flick of a switch, by an ingenious mechanism. The motive power for the ratchet on one side would then be provided by the piston on the opposite side. The pawl is symmetrical, and a spring acts through linkage to apply a small force to bias it to rotate either clockwise or anti-clockwise. Photo here. The pawl and the leaf spring can just be seen in photo 4.

The cylinders and pistons have the appearance of being machined to high standards of accuracy. Photo 8 shows that there is some form of iron or steel piston ring. The cylinders are made from a copper alloy, possibly bronze.

This YouTube animation shows how the pistons drive the wheel and how the steam admission/exhaust valve is operated.

See also here for drawings, dimensions, and animation [3]. Photos showing stages of construction of working replica in 2010 here.

See here for Musée des arts et Métiers photos of details of the engine.

See Also

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Sources of Information

  1. 'Steam on Common Roads' by William Fletcher, first published 1891, reprint published in 1972 by David & Charles
  2. [1] Musée des arts et Métiers: Fardier à vapeur
  3. [2] Website of "Le Fardier de Cugnot" Association