The Newcomen-engine

Newcomen atmospheric engine animation

 

In 1712 Thomas Newcomen presented the first ever working steamengine with moving parts.

Because of the limited technical skills in that time, beginning of the 18th century, the engines were crudely constructed, quality metal work had still to be invented. And the boilers were not capable of producing high pressure steam, all steam had no more than little above atmospheric pressure to prevent steam-explosions. Details about parts and skills are in a seperate page.

The main motivation for the invention of these engines was the urgently needed capacity to pump water from the mines. And pumping was the only thing these engines could do.

On one side of the beam is a pump, on the other site the boiler and cilinder. The weight of the pumprod is significantly higher than the weight of the piston.

The weight of the pumprod pulls down the beam, the piston is pulled up, the valve between boiler and cilinder is open, and the piston sucks the steam in and the cilinder gets filled with steam. Until now no real work is done. When the pumprod is completely down, the valve between boiler and cilinder is closed and a bit of cold water is sprayed inside the cilinder.

Newcomen's engine

The steam condenses and creates a partial vacuĆ¼m in the cilinder. It is then that the pressure of the atmosphere comes in and pushes the piston down in the cilinder. It is this atmospheric pressure that does the actual work. That's why these engines are called "atmospheric" engines.

The fuelconsumption of these engines was enormous. Usage was only feasable next to a coalmine, where fuel was relatively cheap.

The fuelconsumption is that big, because the entire cilinder is cooled at each stroke and has to be reheated completely. here comes the enthalpy in. It is there that Mr Watt applied his biggest improvement on the machine.

It took a long time before this engines were adapted to rotational purposes. The engine ran too slow and too irregular. Because of the big weight of beam, rod and cilinder no more than 5 to 10 strokes per minute were possible.

The building was part of the engine and erecting such an engine took a lot of time and was very expensive. Never the less some 1400 engines are known to be build between 1712 and 1800.

The Newcomen engine in the Black Country MuseumIt is said the first engine was erected in 1712 near Dudley Castle, but there is reason to believe that other test-engines were build before 1712.

The engines were build with bore's from 20 inch to a respectable 75 inch. The output of such an engine could go up to 40 bhp.

After the death of Newcomen in 1717 the Proprietors of the Invention for Raising Water by Fire took over.

Only one genuine engine is saved, the engine in Elsecar, erected in 1795. Several replica's are erected and parts of original engines can be seen in museums all over the world. The only working engine can be found in the Black Country Museum in Dudley.